,四川农业大学玉米研究所,农业部西南玉米生物学与遗传育种重点实验室,温江 611130The BES1/BZR1 transcription factors regulate growth, development and stress resistance in plants
Haoqiang Yu, Fuai Sun, Wenqi Feng, Fengzhong Lu, Wanchen Li, Fengling Fu,Maize Research Institute, Sichuan Agricultural University, Chengdu 611130, China通讯作者:
编委: 张宪省
收稿日期:2018-09-7修回日期:2019-02-20网络出版日期:2019-02-25
| 基金资助: |
Received:2018-09-7Revised:2019-02-20Online:2019-02-25
| Fund supported: |
作者简介 About authors
于好强,博士,讲师,研究方向：植物分子生物学E-mail:yhq1801@sicau.edu.cn。
摘要
关键词：
Abstract
Keywords：
PDF (625KB)元数据多维度评价相关文章导出EndNote|Ris|Bibtex收藏本文
本文引用格式
于好强, 孙福艾, 冯文奇, 路风中, 李晚忱, 付凤玲. 转录因子BES1/BZR1调控植物生长发育及抗逆性[J]. 遗传, 2019, 41(3): 206-214 doi:10.16288/j.yczz.18-253
Haoqiang Yu, Fuai Sun, Wenqi Feng, Fengzhong Lu, Wanchen Li, Fengling Fu.
油菜素内酯(brassinosteroid, BR)是植物特有的甾体激素,在生长发育及环境胁迫应答中起重要作用,其生理活性远高于生长素(auxin, IAA)、赤霉素(gibberellins, GA)、细胞分裂素(cytokinin, CTK)、脱落酸(abscisic acid, ABA)和乙烯(ethylene, ET)[1,2]。BR合成基因过量表达或缺失对植物生长发育及产量、品质等农艺性状育均产生严重影响[3,4,5,6]。BR信号转导被阻断的植物则显现矮化、开花延迟、早衰等缺陷表型[7,8]。
BR被细胞膜上BRASSINOSTEROID INSENSITIVE 1 (BRI1)及BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1)等激酶接受后,通过信号转导激活转录因子BRI1 EMS SUPPRESSOR 1 (BES1)及其同源蛋白BRASSINAZOLE RESISTANT 1 (BZR1)的活性[9,10]。BES1与BZR1氨基酸序列相似性达88%,N端结构域相似性高达97%[11],编码基因以家族形式存在,本课题组在前期研究中将其统一命名为BES1/BZR1[12]。被BR信号激活后,BES1/BZR1直接或与其他转录因子一起结合到生长发育相关基因启动子的E框(CANNTG)或BRRE元件(CGTGT/ CG),调节这些基因的表达[13,14,15]。例如,BES1/BZR1抑制叶腋分生组织发育基因表达,可促进小穗发育,增加水稻产量[16]。BES1/BZR1调节根尖分生组织发育相关基因表达,进而调控根发育[4,17~19]。除介导BR信号,BES1/BZR1还参与ABA、GA及光等信号转导途径,调控植物的生长发育以及抗冻、耐旱、抗病等抗逆性。
本文对转录因子BES1/BZR1通过信号转导调控植物生长发育和抗逆性分子机制的新近研究进展进行了综述,以期为相关研究提供参考。
1 BES1/BZR1介导BR信号转导
2002年,Wang等[20]利用EMS诱变筛选到一个BR合成抑制突变体brassinazole-resistant 1-1D (bzr1- 1D),图位克隆获得BZR1基因,该基因编码核蛋白且受BR诱导。同年,Yin等[21]利用EMS诱变筛选到BR受体抑制因子BES1,受BR诱导并在细胞核中积累。后经证实BES1是一个BZR1类蛋白(BZR1- like protein),二者具有高度的序列相似性,N端均有一个核定位信号(NLS),C端均有22~24个丝氨酸或苏氨酸残基(S/TXXXS/T),该残基是BIN2、GSK-3等激酶磷酸化位点,磷酸化后进入细胞质被14-3-4蛋白降解[16,20,21]。直至2005年,Yin等[10]进一步证实BES1/BZR1是植物中特有的新一类转录因子,也是BR信号转导途径的唯一转录因子。细胞膜上的BRI1、BKI1和BAK1等激酶接受BR信号后,自身磷酸化并催化BRASSINOSTEROID-SIGNALLING KINASE1 (BSK)和CONSTITUTIVE DIFFERENTIAL GROWTH1 (CDG1)磷酸化,BSK与CDG1进一步磷酸化BRI1-SUPPRESSOR1 (BSU1),BSU1催化BRASSINOSTEROID INSENSITIVE2 (BIN2)去磷酸化,导致其自身被蛋白酶体降解,削弱BIN2对BES1/BZR1的磷酸化从而使其活性增加[9,10,21~23],BES1/BZR1通过调节下游靶基因的表达,调控植物的生长发育(图1A)。图1
新窗口打开|下载原图ZIP|生成PPT图1BES1/BZR1参与的信号转导网络
A：BES1/BZR1介导的BR信号转导;B：BES1/BZR1参与的ABA信号途径;C：BES1/BZR1参与的GA信号途径;D：BES1/BZR1参与的光信号途径;E：BES1/BZR1调控逆境应答途径;F：BES1/BZR1参与的生长素、乙烯及其他信号途径。BR：油菜素内酯;BES1/BZR1：转录因子;BKI1、BRI1、BAK1、BSK1及CDG1：蛋白激酶;BSU1：BRI1抑制因子;ABA：脱落酸;GA：赤霉素;PP2C：2C型丝氨酸苏//氨酸蛋白激酶;PP2A：2A型丝氨酸/苏氨酸蛋白激酶;PYL：ABA受体;BIN2：磷酸激酶;ABI3与ABI5：ABA响应的bZIP转录因子;DELLA：赤霉素负调控转录因子;SINAT与COP1：E3泛素连接酶;GATA2与HY5：光形态建成相关转录因子;UVR8：紫外光受体;PIF4：光敏色素互作因子;CRY：隐花色素。RD26与WRKY26：干旱相关转录因子;REF：乙烯应答因子;MEK6：促细胞分裂原活化蛋白激酶;P：磷。
Fig. 1The signal transduction network of BES1/BZR1
BES1/BZR1成员N端均有一个bHLH结构域,可特异性结合到靶基因启动子区的E框或BRRE元件[10,24~26]。此外,多数BES1/BZR1成员均含有能被BIN2等激酶磷酸化的丝氨酸(serine, S)富集位点,个别成员包含一个与蛋白稳定性紧密相关的脯氨酸(proline, P)、谷氨酸(glutamic acid, E)、丝氨酸(serine, S)和苏氨酸(threonine, T)富集区(PEST基序)[10]。目前,拟南芥(Arabidopsis thaliana)和水稻(Oryza stiva)BES1/BZR1基因家族已被全部鉴定：拟南芥AtBES1/BZR1基因家族有6个成员,且功能存在部分冗余[10,20,21];水稻OsBES1/BZR1基因家族有4个成员[27]。玉米(Zea mays)ZmBES1/BZR1基因家族有11个成员[23,28]。此外,从白菜(Brassica rapa ssp. pekinensis)、棉花(Gossypium)、油菜(Brassica napus)和桉树(Eucalyptus grandis)中均鉴定出多个BES1/ BZR1基因家族成员[29,30,31,32,33](表1)。进一步研究证实,BES1/BZR1基因家族成员通过不同信号途径调控植物生理代谢过程,进而调控植物生长发育及逆境响应。
Table 1
表1
表1 已鉴定的不同植物BES1/BZR1基因家族成员
Table 1
| 物种 | 基因家族(数量) | 参考文献 |
|---|---|---|
| 拟南芥(Arabidopsis thaniana) | BES1、BZR1和BEH1 ~ 4(6) | [10, 20, 21] |
| 水稻(Oraza stiva) | OsBZR1 ~ 4、LOC_Os01g08180.1和LOC_Os02g03690.1(6) | [27] |
| 大白菜(Brassica rapa ssp. pekinensis) | BrBEH1 ~ 10、BrBZR1-1 ~ -2和BrBES1-1 ~ -3(15) | [29] |
| 陆地棉(Gossypium hirsutum) | GhBES1-1 ~ -21(21) | [30] |
| 雷蒙德氏棉(Gossypium raimondii) | GrBZR1 ~ 7(7) | [31] |
| 亚洲棉(Gossypium arboreum) | GaBZR1 ~ 7(7) | |
| 桉树(Eucalyptus grandis) | EgrBZR1、EgrBEH1、EgrBEH3、EgrBEH4、EgrBAM7和EgrBAM8(6) | [32] |
| 玉米(Zea mays) | ZmBES1/BZR1-1 ~ -11(11) | [23, 28] |
| 油菜(Brassica napus) | Bna-BES1-001 ~ -028(28) | [33] |
新窗口打开|下载CSV
2 BES1/BZR1参与ABA信号途径
ABA是植物体内重要激素之一,通过其直接受体PYL (pyrabactin resistance 1-like protein)、第二信使2C型蛋白磷酸酶(PP2C)及第三信使蔗糖非酵解型蛋白激酶(SnRK)向下游进行信号传递,在植物生长发育及抗逆过程中扮演重要角色,如衰老、抗旱、耐盐等[34,35,36]。研究发现,在突变体bzr1-1D中,BZR1结合到ABA诱导型转录因子ABA INSENSITIVE 5 (ABI5)编码基因ABI5的启动子,抑制其表达,因而抑制突变体bzr1-1D对ABA诱导的应答[37]。同时,BES1抑制ABA调节的转录因子ABI3编码基因的表达,进而抑制ABI3对下游ABI5转录因子的激活,致使ABA信号转导受阻,表现为苗期发育迟缓[38,39]。此外,外源ABA不仅诱导BES1/BZR1基因表达,而且诱导BES1蛋白磷酸化,使其稳定性降低,从而抑制BR信号转导,此过程依赖于ABA第二信使PP2C成员ABI1和ABI2[12,29,40,41]。最新研究表明,ABI1、ABI2与BIN2激酶互作后催化BIN2去磷酸化,从而调控BES1活性。ABA还可促进BIN2磷酸化并抑制ABI2的活性[42]。在ABA存在时,BIN2磷酸化ABI5使其稳定性增强,调控种子发育过程[43]。在大豆(Glycine max)中,PP2C-1与GmBZR1直接互作,催化GmBZR1去磷酸化以增强GmBZR1活性,促进种子大小相关基因SHORT HYPOCOTYL UNDER BLUE1 (SHB1)、APETALA2 (AP2)和Auxin response factor 2 (ARF2)等表达,调控种子的大小与重量[44,45]。BZR1也可结合到ABA受体PYL6编码基因的启动子区,上调PYL6表达,从而参与PYL6介导的ABA信号转导[46]。研究还发现,BZR1的PEST结构域与蛋白磷酸酶2A(PP2A)的B亚基直接互作,使BZR1被PP2A去磷酸化,激活BZR1介导的BR信号途径,调控植物的生长发育[47](图1B)。
3 BES1/BZR1参与GA信号途径
作为植物体内重要激素之一,GA在种子萌发、细胞分裂、胚珠形成等生长发育过程中起关键作用[48,49]。研究发现,在BR缺失的突变体bri1-1中,GA合成关键基因GA20ox1表达显著下调,而在bzr1-1D突变体中,GA20ox1基因表达显著上调。同时,在bzr1-1D和bes1-D突变体中,GA20ox1基因均受BR诱导,表达显著上调。有研究表明,GA20ox1基因启动子区不含BES1/BZR1转录因子的结合位点。研究人员通过电泳迁移实验(electrophoretic mobility shift assays, EMSA)和染色质免疫共沉淀(chromatin immunoprecipitation, Chip)实验证实,BES1/BZR1可结合GA20ox1基因启动子区一个非E-Box且长度为12 bp的基序(Motif)[50,51]。此外,GA信号负调控因子DELLA家族蛋白(RGA、GAI、RGL1、RGL2和RGL3)可以和BES1/BZR1结合,阻止BES1/BZR1与靶基因的结合[50,52~55]。这些研究结果证实,DELLA蛋白降解可促使BES1/BZR1活性增强,BES1/BZR1结合GA合成相关基因启动子,使其表达上调,促进GA积累。此外,GA可通过PP2A促进BES1/BZR1的去磷酸化[54]。在水稻中,BR诱导GA合成基因表达,促使GA积累。外源GA又抑制BR合成及其信号转导。进一步研究表明,GA合成关键基因GA20ox-2、GA3ox-2、GA2ox-3和D2的启动子均包含CATGTG、BRRE或G-box元件。BES1/BZR1与这类元件直接结合,调节下游基因的表达,进而影响GA合成[56]。在番茄(Lycopersicon esculentum)中过表达BZR1,GA合成关键酶之一的酮戊二酸脱氢酶2 (2-ODD2)蛋白水平在果实成熟期显著增加,致使GA显著积累促进果实成熟[57]。水稻OsBZR1能够促进miR396d的积累,调控其靶基因GROWTH REGULATING FACTOR 6 (OsGRF6)的表达,通过OsGRF6参与的GA合成及信号转导途径,调控水稻株高及叶夹角等形态建成[58](图1C)。
4 BES1/BZR1参与光信号途经
光是植物光合作用的能量之源,在调控植物生长发育中起关键作用,如光信号参与调控种子萌发、光形态建成和开花等[59]。转录因子GATA2、HY5正向调控植物光形态建成并受光诱导积累,黑暗促使其降解。研究发现,被BR激活的BZR1直接与GATA2互作,抑制GATA2转录,调控拟南芥幼苗下胚轴伸长[60,61]。黑暗条件下,HY5能特异地结合BZR1,抑制BZR1与子叶开闭相关基因的结合能力,调控光形态建成[61]。光敏色素互作因子(phytochrome interacting factor,PIF)是一类bHLH转录因子,在黑暗条件下,PIF大量积累,促进植物暗形态建成,但在光照条件下,PIF发生磷酸化后降解,促进植物光形态建成[62,63]。研究发现,BES1/BZR1与PIF 4相互作用,形成异源二聚体后作用于共同靶基因,其中80%靶基因受光诱导参与光形态建成[11]。此外,BZR1与PIF4共同作用的靶基因还受GA诱导,GA促进细胞伸长的过程依赖于BZR1和PIF4。DELLA- BZR1-PIF4复合体调控下游靶基因paclobutrazol resistance家族(PREs)表达,促进细胞伸长,调控光形态建成[11,53]。在高温条件下,BZR1和PIF4相互作用,调控植物热形态建成[64]。最近研究发现,去磷酸化的BES1可与紫外光受体UVR8 (UV RESISTANCE LOCUS 8)互作,二者的复合体受紫外光(UV-B)诱导,并在细胞核大量积累。同时,UV-B不仅抑制BES1靶基因表达,其受体UVR8又抑制BES1与DNA的结合作用,最终控制植物光形态建成过程[65]。在蓝光条件下,其受体隐花色素(cryptochrome, CRY) CRY1和CRY2特异性与去磷酸化的BES1互作,抑制BES1与DNA结合活性及其靶基因表达,最终抑制下胚轴伸长[66]。
综上所述,BES1/BZR1参与光信号途径调控植物的形态建成过程。此外,还有研究发现,植物体内BES1/BZR1的磷酸化状态及稳定性也受光信号调控。黑暗条件促进BES1/BZR1去磷酸化以增强活性,而光照条件下,大多数BZR1被BIN2磷酸化以保持失活状态[61,67,68]。Kim等[68]研究发现,黑暗条件下,E3泛素连接酶COP1催化磷酸化后的BZR1降解,去磷酸化的BZR1积累。同时,光照条件可诱导E3泛素连接酶SINAT积累,SINAT泛素化BES1促使其降解。相反,黑暗条件抑制SINAT的积累,从而阻止BES1降解[69](图1D)。
5 BES1/BZR1调控植物抗逆性
BES1/BZR1除调控植物生长发育外,在响应生物和非生物逆境胁迫过程中也起重要作用。Guo等[70]研究发现,BES1/BZR1调控硫代糖苷合酶基因的表达,促进硫代糖苷合成,而硫代糖苷在植物与食草动物或与微生物互作中起重要作用。随后,Miyaji等[71]发现BZR1可能参与茉莉酸信号途径,增强植物抗虫能力。此外,研究表明,病原物相关分子模式(pathogen-associated molecular pattern, PAMP)感知可促进BES1磷酸化,在PAMP诱导的免疫反应(PAMP-triggered immunity, PTI)过程中,BES1作为病原菌诱导的MITOGEN-ACTIVATED PROTEIN KINASE 6 (MPK6)的直接底物被其磷酸化,参与调控植物对病菌的免疫反应[72]。Singh等[73]研究发现,低磷胁迫促进BES1/ BZR1由细胞核向细胞质转移,低磷条件下,BES1/ BZR1显著积累,维持根系正常生长,赋予拟南芥对低磷胁迫的耐受性。研究表明,BES1/BZR1可促进转录因子CBF (C-repeat binding factor)、WRKY6以及ABA受体PYL6等编码基因的表达,并与WRKY54转录因子直接互作,正调控拟南芥耐寒性,但负调控其耐旱性[46,74]。研究还发现,BES1/BZR1与NAC转录因子家族的RD26存在拮抗关系,BES1/ BZR1结合到RD26基因启动子,抑制RD26表达,而RD26蛋白又与BES1/BZR1蛋白结合,抑制RD26干旱应答调节功能[75]。同时,在干旱和低碳胁迫下,BES1与泛素受体DSK2互作而被降解,参与胁迫诱导的自噬反应过程,调控植物适应逆境[76]。
此外,在拟南芥、油菜和桉树中,BES1/BZR1基因的表达受盐、干旱、热和冷等胁迫的诱导或抑制[29,32,33],表明该基因家族参与这些逆境胁迫响应过程(图1E)。
6 BES1/BZR1参与的信号转导网络
BES1/BZR1是BR信号转导途径特异的转录因子,通过介导BR信号调控植物生长发育。但近年来研究发现,BES1/BZR1在ABA、GA、光及逆境信号中也发挥着重要作用,并且还参与IAA、ET等信号途径。如BZR1直接与生长素诱导基因IAA19、ARF7的启动子结合而抑制其表达,从而影响生长素的合成,调控植物生长发育[77]。BES1/BZR1通过下调乙烯合成关键酶基因ACS7、ACS9和ACS11表达,抑制乙烯合成,而且与乙烯响应因子ERF72互作调控其下游基因表达,最终影响植物生长发育过程[4,78] (图1F)。综上所述,BES1/BZR1参与多种信号途径,调控植物生长发育及逆境应答,其功能和作用机制表现出多样性。但是,BES1/BZR1调控植物响应逆境胁迫方面的研究还不够深入,除拟南芥外,在作物及其他植物中BES1/BZR1抗逆功能研究尚未见报道。因此,本文将BES1/BZR1参与的信号转导网络进行了归纳总结(图1),以期为后续相关研究提供参考。参考文献 原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子
URL [本文引用: 1]
URLPMID:28450180 [本文引用: 1]
@@
URLPMID:26383874 [本文引用: 1]
Summary Brassinosteroids (BRs) play a critical role in plant growth, development and stress response; however, genetic evidence for the BR-mediated integrated regulation of plant growth still remains elusive in crop species. Here, we clarified the function of DWARF ( DWF ), the key BR biosynthetic gene in tomato, in the regulation of plant growth and architecture, phytohormone homeostasis and fruit development by comparing wild type, d ^ im , a weak allele mutant impaired in DWF , and DWF- overexpressing plants in tomato. Results showed that increases in DWF transcripts and endogenous BR level resulted in improved germination, lateral root development, CO2 assimilation and eventually plant growth as characterized by slender and compact plant architecture. However, an increase in DWF transcript down-regulated the accumulation of gibberellin, which was associated with decreases in leaf size and thickness. BRs positively regulated lateral bud outgrowth, which was associated with decreased transcript of Aux/IAA3 , and the ethylene-dependent petiole bending and fruit ripening. Notably, overexpression of DWF did not significantly alter fruit yield per plant; however, increases by 57.4% and 95.3% might be estimated in fruit yield per square metre in two transgenic lines due to their compact architecture. Significantly, BR level was positively related with the carotenoid accumulation in the fruits. Taken together, our results demonstrate that BRs are actively involved in the regulation of multiple developmental processes relating to agronomical important traits.
URL [本文引用: 3]
Brassinosteroid activity controls plant growth and development, often in a seemingly opposing or complex manner. Differential impact of the hormone and its signalling components, acting both as promoters and inhibitors of organ growth, is exemplified by meristem differentiation and cell expansion in above- and below-ground organs. Complex brassinosteroid-based control of stomata count and... [Show full abstract]
URLPMID:4915011 [本文引用: 1]
As a resource allocation strategy, plant growth and defense responses are generally mutually antagonistic. Brassinosteroid (BR) regulates many aspects of plant development and stress responses, however, genetic evidence of its integrated effects on plant growth and stress tolerance is lacking. We overexpressed theArabidopsisBR biosynthetic geneAtDWF4in the oilseed plantBrassica napusand scored growth and stress response phenotypes. The transgenicB. napusplants, in comparison to wild type, displayed increased seed yield leading to increased overall oil content per plant, higher root biomass and root length, significantly better tolerance to dehydration and heat stress, and enhanced resistance to necrotrophic fungal pathogensLeptosphaeria maculansandSclerotinia sclerotiorum.Transcriptome analysis supported the integrated effects of BR on growth and stress responses; in addition to BR responses associated with growth, a predominant plant defense signature, likely mediated by BES1/BZR1, was evident in the transgenic plants. These results establish that BR can interactively and simultaneously enhance abiotic and biotic stress tolerance and plant productivity. The ability to confer pleiotropic beneficial effects that are associated with different agronomic traits suggests that BR elated genes may be important targets for simultaneously increasing plant productivity and performance under stress conditions.
URLPMID:29263085 [本文引用: 1]
Abstract Inflorescence architecture is a key determinant of yield potential in many crops and is patterned by the organization and developmental fate of axillary meristems. In cereals, flowers and grain are borne from spikelets, which differentiate in the final iteration of axillary meristem branching. In Setaria spp., inflorescence branches terminate in either a spikelet or a sterile bristle, and these structures appear to be paired. In this work, we leverage Setaria viridis to investigate a role for the phytohormones brassinosteroids (BRs) in specifying bristle identity and maintaining spikelet meristem determinacy. We report the molecular identification and characterization of the Bristleless 1 (Bsl1) locus in S. viridis, which encodes a rate-limiting enzyme in BR biosynthesis. Loss-of-function bsl1 mutants fail to initiate a bristle identity program, resulting in homeotic conversion of bristles to spikelets. In addition, spikelet meristem determinacy is altered in the mutants, which produce two florets per spikelet instead of one. Both of these phenotypes provide avenues for enhanced grain production in cereal crops. Our results indicate that the spatiotemporal restriction of BR biosynthesis at boundary domains influences meristem fate decisions during inflorescence development. The bsl1 mutants provide insight into the molecular basis underlying morphological variation in inflorescence architecture.
[本文引用: 1]
URLPMID:26162429 [本文引用: 1]
Brassinosteroids (BRs) are plant hormones involved in various growth and developmental processes. The BR signaling system is well established in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) but poorly understood in maize (Zea mays). BRASSINOSTEROID INSENSITIVE1 (BRI1) is a BR receptor, and database searches and additional genomic sequencing identified five maize homologs including duplicate copies of BRI1 itself. RNA interference (RNAi) using the extracellular coding region of a maize zmbri1 complementary DNA knocked down the expression of all five homologs. Decreased response to exogenously applied brassinolide and altered BR marker gene expression demonstrate that zmbri1-RNAi transgenic lines have compromised BR signaling. zmbri1-RNAi plants showed dwarf stature due to shortened internodes, with upper internodes most strongly affected. Leaves of zmbri1-RNAi plants are dark green, upright, and twisted, with decreased auricle formation. Kinematic analysis showed that decreased cell division and cell elongation both contributed to the shortened leaves. A BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1-yellow fluorescent protein (BES1-YFP) transgenic line was developed that showed BR-inducible BES1-YFP accumulation in the nucleus, which was decreased in zmbri1-RNAi. Expression of the BES1-YFP reporter was strong in the auricle region of developing leaves, suggesting that localized BR signaling is involved in promoting auricle development, consistent with the zmbri1-RNAi phenotype. The blade-sheath boundary disruption, shorter ligule, and disrupted auricle morphology of RNAi lines resemble KNOTTED1-LIKE HOMEOBOX (KNOX) mutants, consistent with a mechanistic connection between KNOX genes and BR signaling.
URLPMID:25615890 [本文引用: 2]
Abstract Because they are tethered in space, plants have to make the most of their local growth environment. In order to grow in an ever-changing environment, plants constantly remodel their shapes. This adaptive attribute requires the orchestration of complex environmental signals at the cellular and organismal levels. A battery of small molecules, classically known as phytohormones, allows plants to change their body plan by using highly integrated signaling networks and transcriptional cascades. Amongst these hormones, brassinosteroids (BRs), the polyhydroxylated steroid of plants, influence plant responsiveness to the local environment and exquisitely promote, or interfere with, many aspects of plant development. The molecular circuits that wire steroid signals at the cell surface to the promoters of thousands of genes in the nucleus have been defined in the past decade. This review recapitulates how the transduction of BR signals impacts the temporally unfolding programs of plant growth. First, we summarize the paradigmatic BR signaling pathway acting primarily in cellular expansion. Secondly, we describe the current wiring diagram and the temporal dynamics of the BR signal transduction network. And finally we provide an overview of how key players in BR signaling act as molecular gates to transduce BR signals onto other signaling pathways. 2015 The Authors. New Phytologist 2015 New Phytologist Trust.
[本文引用: 6]
URLPMID:23020777 [本文引用: 3]
In plants, the steroidal hormone brassinosteroid (BR) regulates numerous developmental processes, including photomorphogenesis. Genetic, proteomic, and genomic studies in Arabidopsis have illustrated a fully connected BR signal transduction pathway from the cell surface receptor kinase BRI1 to the BZR1 family of transcription factors. Genome-wide analyses of protein-DNA interactions have identified thousands of BZR1 target genes that link BR signaling to various cellular, metabolic, and developmental processes, as well as other signaling pathways. In controlling photomorphogenesis, BR signaling is highly integrated with the light, gibberellin, and auxin pathways through both direct interactions between signaling proteins and transcriptional regulation of key components of these pathways.
URL [本文引用: 2]
BES1/BZR1 transcription factors regulate the expression of brassinosteroid-responsive genes and play vital roles in plant growth and response to environmental stimuli. Their regulation mechanism has...
URLPMID:22820378 [本文引用: 1]
Abstract Plant growth is coordinately regulated by environmental and hormonal signals. Brassinosteroid (BR) plays essential roles in growth regulation by light and temperature, but the interactions between BR and these environmental signals remain poorly understood at the molecular level. Here, we show that direct interaction between the dark- and heat-activated transcription factor phytochrome-interacting factor 4 (PIF4) and the BR-activated transcription factor BZR1 integrates the hormonal and environmental signals. BZR1 and PIF4 interact with each other in vitro and in vivo, bind to nearly 2,000 common target genes, and synergistically regulate many of these target genes, including the PRE family helix-loop-helix factors required for promoting cell elongation. Genetic analysis indicates that BZR1 and PIFs are interdependent in promoting cell elongation in response to BR, darkness or heat. These results show that the BZR1-PIF4 interaction controls a core transcription network, enabling plant growth co-regulation by the steroid and environmental signals.
URLPMID:28100707 [本文引用: 1]
Brassinosteroids (BRs) are plant-specific steroid hormones that control plant growth and development. Recent studies have identified key components of the BR signaling pathway in Arabidopsis thaliana and in rice (Oryza sativa); however, the mechanism of BR signaling in rice, especially downstream of GSK3/SHAGGY-like kinase (GSK2), remains unclear. Here, we identified a BR-insensitive rice mutant, reduced leaf angle1 (rla1), and cloned the corresponding gene. RLA1 was identical to the previously reported SMALL ORGAN SIZE1 (SMOS1), which was cloned from another allele. RLA1/SMOS1 encodes a transcription factor with an APETALA2 DNA binding domain. Genetic analysis indicated that RLA1/SMOS1 functions as a positive regulator in the BR signaling pathway and is required for the function of BRASSINAZOLE-RESISTANT1 (OsBZR1). In addition, RLA1/SMOS1 can interact with OsBZR1 to enhance its transcriptional activity. GSK2 can interact with and phosphorylate RLA1/SMOS1 to reduce its stability. These results demonstrate that RLA1/SMOS1 acts as an integrator of the transcriptional complex directly downstream of GSK2 and plays an essential role in BR signaling and plant development in rice.
[本文引用: 1]
URLPMID:29085070 [本文引用: 2]
Abstract Transcriptional silencer and copy number variants (CNVs) are associated with gene expression. However, their roles in generating phenotypes have not been well studied. Here we identified a rice quantitative trait locus, SGDP7 (Small Grain and Dense Panicle 7). SGDP7 is identical to FZP (FRIZZY PANICLE), which represses the formation of axillary meristems. The causal mutation of SGDP7 is an 18-bp fragment, named CNV-18bp, which was inserted ~5.3 kb upstream of FZP and resulted in a tandem duplication in the cultivar Chuan 7. The CNV-18bp duplication repressed FZP expression, prolonged the panicle branching period and increased grain yield by more than 15% through substantially increasing the number of spikelets per panicle (SPP) and slightly decreasing the 1,000-grain weight (TGW). The transcription repressor OsBZR1 binds the CGTG motifs in CNV-18bp and thereby represses FZP expression, indicating that CNV-18bp is the upstream silencer of FZP. These findings showed that the silencer CNVs coordinate a trade-off between SPP and TGW by fine-tuning FZP expression, and balancing the trade-off could enhance yield potential.
URLPMID:25649439 [本文引用: 1]
Brassinosteroids (BRs) are essential steroid hormones that regulate plant growth and development. The transcription factor BRI1-EMS-SUPPRESSOR1 (BES1) regulates the expression of thousands of target genes in response to BRs. Here, we report an Arabidopsis thaliana-specific long isoform of BES1, BES1-L, which has stronger activity in promoting BR signaling than the canonical and widely used short BES1-S. The BES1-L isoform contains an additional N-terminal bipartite nuclear localization signal, which strongly promotes its nuclear localization. BES1-L also promotes the nuclear localization of BES1-S and BRASSINAZOLE-RESISTANT1 via dimerization. The transcription of BES1-L and BES1-S is differentially regulated by BRs due to the presence of G-box element in the BES1-S promoter. Moreover, BES1-L uniquely exists in the majority of A. thaliana ecotypes, but not in other species, even its Brassicaceae relatives, including Arabidopsis lyrata. The phenotypes of the BES1-L overexpression lines and plants with truncated BES1-L indicate that BES1-L is a more important isoform of BES1 in Arabidopsis and may have contributed to the evolution and expansion of A. thaliana.
URLPMID:28827608
Abstract Due to their sessile nature, plants have to cope with and adjust to their fluctuating environment. Temperature elevation stimulates the growth of Arabidopsis aerial parts. This process is mediated by increased biosynthesis of the growth-promoting hormone auxin. How plant roots respond to elevated ambient temperature is however still elusive. Here we present strong evidence that temperature elevation impinges on brassinosteroid hormone signaling to alter root growth. We show that elevated temperature leads to increased root elongation, independently of auxin or factors known to drive temperature-mediated shoot growth. We further demonstrate that brassinosteroid signaling regulates root responses to elevated ambient temperature. Increased growth temperature specifically impacts on the level of the brassinosteroid receptor BRI1 to downregulate brassinosteroid signaling and mediate root elongation. Our results establish that BRI1 integrates temperature and brassinosteroid signaling to regulate root growth upon long-term changes in environmental conditions associated with global warming.Moderate heat stimulates the growth of Arabidopsis shoots in an auxin-dependent manner. Here, Martins et al. show that elevated ambient temperature modifies root growth by reducing the BRI1 brassinosteroid-receptor protein level and downregulating brassinosteroid signaling.
URLPMID:5014150 [本文引用: 1]
Brassinosteroid-regulated transcription factor BES1 targets theBRL3receptor gene and finely modulates its transcription in the vascular and stem cells of the Arabidopsis primary root. Brassinosteroid (BR) hormones are important regulators of plant growth and development. Recent studies revealed the cell-specific role of BRs in vascular and stem cell development by the action of cell-specific BR receptor complexes and downstream signaling components inArabidopsis thaliana. Despite the importance of spatiotemporal regulation of hormone signaling in the control of plant vascular development, the mechanisms that confer cellular specificity to BR receptors within the vascular cells are not yet understood. The present work shows that BRI1-like receptor genes 1 and 3 (BRL1andBRL3) are differently regulated by BRs. By using promoter deletion constructs ofBRL1andBRL3fused to GFP/GUS (green fluorescent protein/ -glucuronidase) reporters in Arabidopsis, analysis of their cell-specific expression and regulation by BRs in the root apex has been carried out. We found thatBRL3expression is finely modulated by BRs in different root cell types, whereas the location ofBRL1appears to be independent of this hormone. Physiological and genetic analysis show a BR-dependent expression ofBRL3in the root meristem. In particular,BRL3expression requires active BES1, a central transcriptional effector within the BRI1 pathway. ChIP analysis showed that BES1 directly binds to the BRRE present in theBRL3promoter region, modulating its transcription in different subsets of cells of the root apex. Overall our study reveals the existence of a cell-specific negative feedback loop from BRI1-mediated BES1 transcription factor toBRL3in phloem cells, while contributing to a general understanding of the spatial control of steroid signaling in plant development.
URLPMID:11970900 [本文引用: 3]
Plant steroid hormones, brassinosteroids (BRs), are perceived by a cell surface receptor kinase, BRI1, but how BR binding leads to regulation of gene expression in the nucleus is unknown. Here we describe the identification of BZR1 as a nuclear component of the BR signal transduction pathway. A dominant mutation bzr1- 1D suppresses BR-deficient and BR-insensitive ( bri1) phenotypes and enhances feedback inhibition of BR biosynthesis. BZR1 protein accumulates in the nucleus of elongating cells of dark-grown hypocotyls and is stabilized by BR signaling and the bzr1-1D mutation. Our results demonstrate that BZR1 is a positive regulator of the BR signaling pathway that mediates both downstream BR responses and feedback regulation of BR biosynthesis.
URLPMID:12007405 [本文引用: 4]
Plant steroid hormones, known as brassinosteroids (BRs), signal through a plasma membrane localized receptor kinase BRI1. We identified bes1, a semidominant suppressor of bri1, which exhibits constitutive BR response phenotypes including long and bending petioles, curly leaves, accelerated senescence, and constitutive expression of BR-response genes. BES1 accumulates in the nucleus in response to BRs. BES1 is phosphorylated and appears to be destabilized by the glycogen synthase kinase-3 (GSK-3) BIN2, a negative regulator of the BR pathway. These results establish a signaling cascade for BRs with similarities to the Wnt pathway, in which signaling through cell surface receptors leads to inactivation of a GSK-3 allowing accumulation of a nuclear protein that regulates target gene expression.
URL
URLPMID:3206214 [本文引用: 2]
The brassinosteroid (BR) signaling pathway includes two receptor-like kinases (BRI1 and BAK1), a plasma membrane-associated kinase (BSK1), two phosphatases (BSU1 and PP2A), a GSK3-like kinase (BIN2), and two homologous transcription factors (BZR1 and BES1/BZR2). But the mechanisms of signal relay are not fully understood. Here, we show that a receptor-like cytoplasmic kinase named CDG1 mediates signal transduction from BRI1 to BSU1. Transgenic experiments confirm that CDG1 and its homolog CDL1 positively regulate BR signaling and plant growth. Mass spectrometry analysis identified BRI1 phosphorylation sites in CDG1 and CDG1 phosphorylation sites in BSU1. Mutations of these phosphorylation sites compromised the BR signaling functions. The results demonstrate that BRI1 phosphorylates S234 to activate CDG1 kinase, and CDG1 in turn phosphorylates S764 to activate BSU1, which inactivates BIN2 by dephosphorylating Y200 of BIN2. This study thus demonstrates a complete phosphorylation/dephosphorylation cascade linking a steroid-activated receptor kinase to a GSK3-like kinase in plants.Graphical AbstractView high quality image (110K)
URLPMID:2925132 [本文引用: 1]
Abstract Brassinosteroid (BR) homeostasis and signaling are crucial for normal growth and development of plants. BR signaling through cell-surface receptor kinases and intracellular components leads to dephosphorylation and accumulation of the nuclear protein BZR1. How BR signaling regulates gene expression, however, remains unknown. Here we show that BZR1 is a transcriptional repressor that has a previously unknown DNA binding domain and binds directly to the promoters of feedback-regulated BR biosynthetic genes. Microarray analyses identified additional potential targets of BZR1 and illustrated, together with physiological studies, that BZR1 coordinates BR homeostasis and signaling by playing dual roles in regulating BR biosynthesis and downstream growth responses.
URLPMID:21074725
Brassinosteroids (BRs) regulate a wide range of developmental and physiological processes in plants through a receptor-kinase signaling pathway that controls the BZR transcription factors. Here, we use transcript profiling and chromatin-immunoprecipitation microarray (ChIP-chip) experiments to identify 953 BR-regulated BZR1 target (BRBT) genes. Functional studies of selected BRBTs further demonstrate roles in BR promotion of cell elongation. The BRBT genes reveal numerous molecular links between the BR-signaling pathway and downstream components involved in developmental and physiological processes. Furthermore, the results reveal extensive crosstalk between BR and other hormonal and light-signaling pathways at multiple levels. For example, BZR1 not only controls the expression of many signaling components of other hormonal and light pathways but also coregulates common target genes with light-signaling transcription factors. Our results provide a genomic map of steroid hormone actions in plants that reveals a regulatory network that integrates hormonal and light-signaling pathways for plant growth regulation.Graphical AbstractView high quality image (437K)
[本文引用: 1]
URL [本文引用: 1]
URL [本文引用: 1]
Brassinosteroids (BRs) are plant specific steroidal hormones that play diverse roles in regulating a broad spectrum of plant growth and developmental processes, as well as, in responding to various biotic and abiotic stresses. Extensive research over the years has established stress-impact-mitigating role of BRs and associated compounds in different plants exposed to various abiotic and biotic stresses, suggesting the idea that they may act as immunomodulators, thus opening new approaches for plant resistance against hazardous environmental conditions. In this research the characterization of the transcriptional response of 11 transcription factors (TFs) belonging to BRASSINAZOLE-RESISTANT 1 (BZR1) TF family of Zea mays L. was analyzed in seedlings subjected to different stress conditions. Being important regulators of the BR synthesis, BZR TFs might have stress resistance related activities. However, no stress resistance related functional study of BZR TFs has been reported in maize so far. In silico analyses of the selected 11 TFs validated the features of their protein domains, where the highest degree of similarity observed with recognized BZR TFs of rice and Sorghum bicolor . Additionally, we investigated the organ-specific expression of 11 ZmBZR in maize seedlings. Five of them did not show any transcript accumulation, suggesting that ZmBZR expression might be regulated in a manner dependent on plant developmental stage. For the remaining six ZmBZR , their ubiquitous expression in the whole plant indicates they could function as growth regulators during maize development. More importantly, in response to various stress conditions, the spatial transcript accumulation of all ZmBZR varies along the plant. All six ZmBZR showed up-regulation against N starvation, hypoxia and salt stress. On the contrary, heat stress clearly down-regulated gene expression of all ZmBZR analysed. Consistently with the expression results, the distribution of stress-related cis- acting elements in the promoter of these genes inferred that the maize BZR TFs might play some roles in regulating the expression of the corresponding genes in response to multifarious stresses. In conclusion, these data reveal that BZR TFs have stress signaling activity in maize, in addition to their confirmed role in regulating plant physiology and morphology.
URLPMID:25931321 [本文引用: 3]
61Fifteen (15) BZR TFs were identified and characterized in Brassica rapa.61All BrBZR TFs constitutively expressed in different flower bud developmental stages.61All BrBZR TFs were induced by abiotic (cold, salt and drought) and hormone (ABA) stresses.61Three (3) BrBZR TFs showed multiple resistances against the stresses.
URL [本文引用: 1]
BES1基因是植物激素油菜素内酯信号转导过程中的重要转录因子,为了解陆地棉油菜素内酯信号基因Gh BESI家族,通过对陆地棉异源四倍体标准系TM-1基因组数据库的全面分析和鉴定,获得21个GhBES1基因,这些基因分布在不同的亚基因组,有9对基因在A亚组和D亚组上存在对应关系,AD亚组对应基因序列一致性高于95%。根据进化分析,21个GhBES1基因分为4个亚家族,除了亚家族Ⅲ,其他3个亚家族在拟南芥中均有对应基因;除了亚家族Ⅳ基因和亚家族Ⅱ中GhBES1-1基因外,其他GhBES1基因均有2个外显子。亚细胞定位结果表明,21个GhBES1蛋白主要定位到细胞核、细胞质等部位,其中7对基因的蛋白亚细胞定位完全一致。GhBES1基因在根、茎、叶、顶端分生组织中均有表达,但不同亚家族基因在不同组织中的表达水平存在差异。研究结果为棉花GhBES1基因家族功能的深入研究奠定了基础。
URL [本文引用: 1]
BES1基因是植物激素油菜素内酯信号转导过程中的重要转录因子,为了解陆地棉油菜素内酯信号基因Gh BESI家族,通过对陆地棉异源四倍体标准系TM-1基因组数据库的全面分析和鉴定,获得21个GhBES1基因,这些基因分布在不同的亚基因组,有9对基因在A亚组和D亚组上存在对应关系,AD亚组对应基因序列一致性高于95%。根据进化分析,21个GhBES1基因分为4个亚家族,除了亚家族Ⅲ,其他3个亚家族在拟南芥中均有对应基因;除了亚家族Ⅳ基因和亚家族Ⅱ中GhBES1-1基因外,其他GhBES1基因均有2个外显子。亚细胞定位结果表明,21个GhBES1蛋白主要定位到细胞核、细胞质等部位,其中7对基因的蛋白亚细胞定位完全一致。GhBES1基因在根、茎、叶、顶端分生组织中均有表达,但不同亚家族基因在不同组织中的表达水平存在差异。研究结果为棉花GhBES1基因家族功能的深入研究奠定了基础。
URL [本文引用: 1]
[目的]油菜素唑抗性因子(Brassinazole resistant transcription factor,BZR)是植物油菜素内酯(Brassinosteroid,BR)信号通路中的l类重要转录因子,通过调控相关基因的表达,参与植物生长发育过程.本研究旨在探索棉花中BZR基因的数量及其功能.[方法]利用生物信息学方法,对雷蒙德氏棉、亚洲棉和陆地棉中的BZR基因进行全基因组鉴定及表达模式分析.[结果]雷蒙德氏棉、亚洲棉和陆地棉中分别有7、7和14个BZR基因;通过序列特征分析和系统发育分析可将棉花BZR基因分为2组(a组和b组).内含子/外显子结构分析发现:大部分BZR基因具有2个外显子,a组成员中均具有较长的内含子序列,b组成员的内含子序列较短,同组BZR成员具有相似的基因结构.基因复制分析表明:片段复制是棉花BZR基因家族扩增的主要方式,棉花BZR基因在进化过程中经历了严格的纯化选择.转录组数据分析表明:14个GhBZR基因在陆地棉的7个组织中特异表达,大多数GhBZR基因在茎、叶、花瓣和雌蕊中高表达;许多GhBZR基因的表达受非生物胁迫诱导.[结论]推测GhBZR基因可能参与棉花抗逆及纤维发育.本研究结果可为棉花BZR基因的生物学功能研究提供信息.
URL [本文引用: 1]
[目的]油菜素唑抗性因子(Brassinazole resistant transcription factor,BZR)是植物油菜素内酯(Brassinosteroid,BR)信号通路中的l类重要转录因子,通过调控相关基因的表达,参与植物生长发育过程.本研究旨在探索棉花中BZR基因的数量及其功能.[方法]利用生物信息学方法,对雷蒙德氏棉、亚洲棉和陆地棉中的BZR基因进行全基因组鉴定及表达模式分析.[结果]雷蒙德氏棉、亚洲棉和陆地棉中分别有7、7和14个BZR基因;通过序列特征分析和系统发育分析可将棉花BZR基因分为2组(a组和b组).内含子/外显子结构分析发现:大部分BZR基因具有2个外显子,a组成员中均具有较长的内含子序列,b组成员的内含子序列较短,同组BZR成员具有相似的基因结构.基因复制分析表明:片段复制是棉花BZR基因家族扩增的主要方式,棉花BZR基因在进化过程中经历了严格的纯化选择.转录组数据分析表明:14个GhBZR基因在陆地棉的7个组织中特异表达,大多数GhBZR基因在茎、叶、花瓣和雌蕊中高表达;许多GhBZR基因的表达受非生物胁迫诱导.[结论]推测GhBZR基因可能参与棉花抗逆及纤维发育.本研究结果可为棉花BZR基因的生物学功能研究提供信息.
URL [本文引用: 2]
Brassinosteroids (BRs) are a group of plant hormones which play a pivotal role in modulating cell elongation, stress responses, vascular differentiation and senescence. In response to BRs,...
URL [本文引用: 2]
TheBES1gene family, an important class of plant-specific transcription factors, play key roles in the BR signal pathway in plants, regulating various development processes. Until now, there has been no comprehensive analysis of theBES1gene family inBrassica napus, and a cross-genome exploration of their origin, copy number changes, and functional innovation in plants was also not available. We identified 28BES1genes inB. napusfrom its two subgenomes (AA and CC). We found that 71.43% of them were duplicated in the tetraploidization, and their gene expression showed a prominent subgenome bias in the roots. Additionally, we identified 104BES1genes in another 18 representative angiosperms and performed a comparative analysis withB. napus, including evolutionary trajectory, gene duplication, positive selection, and expression pattern. Exploiting the available genome datasets, we performed a large-scale analysis across plants and algae suggested that theBES1gene family could have originated from group F, expanding to form other groups (A to E) by duplicating or alternatively deleting some domains. We detected an additional domain containing M4 to M8 in exclusively groups F1 and F2. We found evidence that whole-genome duplication (WGD) contributed the most to the expansion of this gene family among examined dicots, while dispersed duplication contributed the most to expansion in certain monocots. Moreover, we inferred that positive selection might have occurred on major phylogenetic nodes during the evolution of plants. Grossly, a cross-genome comparative analysis of theBES1genes inB. napusand other species sheds light on understanding its copy number expansion, natural selection, and functional innovation. The online version of this article (10.1186/s12864-018-4744-4) contains supplementary material, which is available to authorized users.
URL [本文引用: 1]
脱落酸(ABA)是一种重要的植物激素,调节多种植物生理过程,并在植物应答逆境胁迫的信号转导中起重要作用.结构分子生物学分析发现,PYL蛋白具有结合ABA的活性中心.在非胁迫条件下,ABA水平较低,2C型蛋白磷酸酶(PP2C)与蔗糖非酵解型蛋白激酶2(SnRK2)结合,催化其去磷酸化而抑制其活性;在胁迫条件下,ABA水平升高,促进PYL与PP2C结合而抑制其磷酸酶活性,SnRK2靠自身磷酸化激活,又催化碱性亮氨酸拉链(bZIP)、碱性螺旋-环-螺旋(bHLH)等类型转录因子,调控下游抗性相关基因的表达,也可由SnRK2直接催化下游抗性相关蛋白磷酸化.本文概述了在ABA胁迫下,PYL,PP2C和SnPK2作用机制的相关研究进展,并建议将PYL、PP2C和SnRK2分别称做ABA信号转导途径的直接受体、第二信使和第三信使,建立玉米中复杂的脱落酸信号上淳传递网络.
URL [本文引用: 1]
脱落酸(ABA)是一种重要的植物激素,调节多种植物生理过程,并在植物应答逆境胁迫的信号转导中起重要作用.结构分子生物学分析发现,PYL蛋白具有结合ABA的活性中心.在非胁迫条件下,ABA水平较低,2C型蛋白磷酸酶(PP2C)与蔗糖非酵解型蛋白激酶2(SnRK2)结合,催化其去磷酸化而抑制其活性;在胁迫条件下,ABA水平升高,促进PYL与PP2C结合而抑制其磷酸酶活性,SnRK2靠自身磷酸化激活,又催化碱性亮氨酸拉链(bZIP)、碱性螺旋-环-螺旋(bHLH)等类型转录因子,调控下游抗性相关基因的表达,也可由SnRK2直接催化下游抗性相关蛋白磷酸化.本文概述了在ABA胁迫下,PYL,PP2C和SnPK2作用机制的相关研究进展,并建议将PYL、PP2C和SnRK2分别称做ABA信号转导途径的直接受体、第二信使和第三信使,建立玉米中复杂的脱落酸信号上淳传递网络.
URL [本文引用: 1]
URL [本文引用: 1]
蔗糖非发酵相关激酶(sucrose non-fermenting related protein kinases,Sn RKs)是广泛存在于植物中的一类Ser/Thr蛋白激酶,在植物的生长、发育、代谢和抗逆等方面具有重要调节作用。大豆(Glycine max L.)基因组中含有4个Sn RK1同源基因,其中GmSnRK1.1和GmSnRK1.2为两个主要表达基因,可能参与大豆多种抗逆途径。为解析大豆GmSnRK1.1和GmSnRK1.2对ABA及碱胁迫的响应,本研究构建了双靶点CRISPR载体定向敲除GmSnRK1.1和GmSnRK1.2基因,利用发根农杆菌(Agrobacterium rhizogenes)介导大豆遗传转化,获得双基因敲除突变体毛状根,经测序鉴定双基因突变率为48.6%;同时,利用实验室前期构建的植物超量表达载体获得超量表达GmSnRK1基因大豆毛状根。经25μmol/L ABA处理15 d,对照组和超量表达毛状根的生长受到明显抑制,其根长与根鲜重均显著低于双基因敲除突变体毛状根;经50 mmol/L Na HCO3处理15 d,对照组和双基因敲除突变体毛状根的生长受到明显抑制,其根长与根鲜重均显著低于超量表达毛状根。本研究建立的CRISPR/Cas9系统能够有效地对大豆进行GmSnRK1.1和GmSnRK1.2双基因敲除,基因敲除突变降低了植物对ABA的敏感性及对碱胁迫的耐性,研究结果初步说明Sn RK1激酶在植物响应非生物胁迫中具有重要作用。
URL [本文引用: 1]
蔗糖非发酵相关激酶(sucrose non-fermenting related protein kinases,Sn RKs)是广泛存在于植物中的一类Ser/Thr蛋白激酶,在植物的生长、发育、代谢和抗逆等方面具有重要调节作用。大豆(Glycine max L.)基因组中含有4个Sn RK1同源基因,其中GmSnRK1.1和GmSnRK1.2为两个主要表达基因,可能参与大豆多种抗逆途径。为解析大豆GmSnRK1.1和GmSnRK1.2对ABA及碱胁迫的响应,本研究构建了双靶点CRISPR载体定向敲除GmSnRK1.1和GmSnRK1.2基因,利用发根农杆菌(Agrobacterium rhizogenes)介导大豆遗传转化,获得双基因敲除突变体毛状根,经测序鉴定双基因突变率为48.6%;同时,利用实验室前期构建的植物超量表达载体获得超量表达GmSnRK1基因大豆毛状根。经25μmol/L ABA处理15 d,对照组和超量表达毛状根的生长受到明显抑制,其根长与根鲜重均显著低于双基因敲除突变体毛状根;经50 mmol/L Na HCO3处理15 d,对照组和双基因敲除突变体毛状根的生长受到明显抑制,其根长与根鲜重均显著低于超量表达毛状根。本研究建立的CRISPR/Cas9系统能够有效地对大豆进行GmSnRK1.1和GmSnRK1.2双基因敲除,基因敲除突变降低了植物对ABA的敏感性及对碱胁迫的耐性,研究结果初步说明Sn RK1激酶在植物响应非生物胁迫中具有重要作用。
URLPMID:27149247 [本文引用: 1]
Abstract Brassinosteroids (BRs) and abscisic acid (ABA) are plant hormones that antagonistically regulate many aspects of plant growth and development; however, the mechanisms that regulate the crosstalk of these two hormones are still not well understood. BRs regulate plant growth and development by activating BRASSINAZOLE RESISTANT 1 (BZR1) family transcription factors. Here we show that the crosstalk between BRs and ABA signalling is partially mediated by BZR1 regulated gene expression. bzr1-1D is a dominant mutant with enhanced BR signalling; our results showed that bzr1-1D mutant is less sensitive to ABA-inhibited primary root growth. By RNA sequencing, a subset of BZR1 regulated ABA-responsive root genes were identified. Of these genes, the expression of a major ABA signalling component ABA INSENSITIVE 5 ( ABI5 ) was found to be suppressed by BR and by BZR1. Additional evidences showed that BZR1 could bind strongly with several G-box cis -elements in the promoter of ABI5 , suppress the expression of ABI5 and make plants less sensitive to ABA. Our study demonstrated that ABI5 is a direct target gene of BZR1, and modulating the expression of ABI5 by BZR1 plays important roles in regulating the crosstalk between the BR and ABA signalling pathways.
URLPMID:12410810 [本文引用: 1]
The development of a germinating embryo into an autotrophic seedling is arrested under conditions of water deficit. This ABA-mediated developmental checkpoint requires the bZIP transcription factor ABI5. Here, we used abi3-1 , which is also unable to execute this checkpoint, to investigate the relative role of ABI3 and ABI5 in this process. In wild-type Arabidopsis plants, ABI3 expression and activity parallel those described for ABI5 following stratification. During this process, transcript levels of late embryogenesis genes such as AtEm1 and AtEm6 are also re-induced, which might be responsible for the acquired osmotic tolerance in germinated embryos whose growth is arrested. ABI5 expression is greatly reduced in abi3-1 mutants, which has low AtEm1 or AtEm6 expression. Cross complementation experiments showed that 35S-ABI5 could complement abi3-1 , whereas 35S-ABI3 cannot complement abi5-4 . These results indicate that ABI5 acts downstream of ABI3 to reactivate late embryogenesis programmes and to arrest growth of germinating embryos. Although ABI5 is consistently located in the nucleus, chromosomal immunoprecipitation (ChIP) experiments revealed that ABA increases ABI5 occupancy on the AtEm6 promoter.
URLPMID:24938150 [本文引用: 1]
Abstract Seed germination and young seedling establishment should be tightly regulated to maximize plant survival and thereby enable successful propagation. Plants have evolved developmental signalling networks to integrate environmental cues for proper control of these critical processes, in which brassinosteroids are known to attenuate ABA-mediated arrest of early seedling development; however, the underlying regulatory mechanism remains elusive. Here we reveal that a BES1/TPL/HDA19 repressor complex mediates the inhibitory action of brassinosteroids on ABA responses during early seedling development. BR-activated BES1 forms a transcriptional repressor complex with TPL-HDA19, which directly facilitates the histone deacetylation of ABI3 chromatin. This event leads to the transcriptional repression of ABI3 and consequently ABI5, major ABA signalling regulators in early seedling development. Our data reveal that the BR-activated BES1-TPL-HDA19 repressor complex controls epigenetic silencing of ABI3 and thereby suppresses the ABA signalling output during early seedling development.
PMID:12114546 [本文引用: 1]
Brassinosteroids (BRs) are a class of steroid hormones essential for normal growth and development in plants. BR signaling involves the cell-surface receptor BRI1, the glycogen synthase kinase-3-like kinase BIN2 as a negative regulator, and nuclear proteins BZR1 and BZR2/BES1 as positive regulators. The interactions among these components remain unclear. Here we report that BRs induce dephosphorylation and accumulation of BZR1 protein. Experiments using a proteasome inhibitor, MG132, suggest that phosphorylation of BZR1 increases its degradation by the proteasome machinery. BIN2 directly interacts with BZR1 in yeast two-hybrid assays, phosphorylates BZR1 in vitro, and negatively regulates BZR1 protein accumulation in vivo. These results strongly suggest that BIN2 phosphorylates BZR1 and targets it for degradation and that BR signaling causes BZR1 dephosphorylation and accumulation by inhibiting BIN2 activity.
URLPMID:19240210 [本文引用: 1]
Phytohormones have essential roles in coordinately regulating a large array of developmental processes. Studies have revealed that brassinosteroids (BRs) and abscisic acid (ABA) interact to regulate hundreds of expression in genes, governing many biological processes. However, whether their interaction is through modification or intersection of their primary signaling cascades, or by independent or parallel pathways remains a big mystery. Using biochemical and molecular markers of BR signaling and ABA biosynthetic mutants, we demonstrated that exogenous ABA rapidly inhibits BR signaling outputs as indicated by the phosphorylation status of BES1 and BR-responsive gene expression. Experiments using a bri1 null-allele, bri1-116, and analysis of subcellular localization of BKI1-YFP further revealed that the BR receptor complex is not required for ABA to act on BR signaling outputs. However, when the BR downstream signaling component BIN2 is inhibited by LiCI, ABA failed to inhibit BR signaling outputs. Also, using a set of ABA insensitive mutants, we found that regulation of ABA on the BR primary signaling pathway depends on the ABA early signaling components, ABI1 and ABI2. We propose that the signaling cascades of ABA and BR primarily cross-talk after BR perception, but before their transcriptional activation. This model provides a reasonable explanation for why a large proportion of BR-responsive genes are also regulated by ABA, and provides an insight into the molecular mechanisms by which BRs could interact with ABA.
URLPMID:29275167 [本文引用: 1]
Abscisic acid (ABA) and brassinosteroid (BR) antagonistically regulate many aspects of plant growth and development.Previous physiological studies have revealed that the inhibition of BR signaling by ABA is largely dependent on ABI1 and ABI2.However,the genetic and molecular basis of how ABI1 and ABI2 are involved in inhibiting BR signaling remains unclear.Although it is known that in the BR signaling pathway the ABA-BR crosstalk occurs in the downstream of BR receptor complex but upstream of BIN2 kinase,a negative regulator of BR signaling,the component that acts as the hub to directly mediate their crosstalk remains a big mystery.Here,we found that ABI1 and ABI2 interact with and dephosphorylate BIN2 to regulate its activity toward the phosphorylation of BES1.By in vitro mimicking ABA signal transduction,we found that ABA can promote BIN2 phosphorylation by inhibiting ABI2 through ABA receptors.RNA-sequencing analysis further demonstrated that ABA inhibits BR signaling through the ABA primary signaling components,including its receptors and ABI2,and that ABA and GSK3s co-regulate a common set of stressresponsive genes.Because BIN2 can interact with and phosphorylate SnRK2s to activate its kinase activity,our study also reveals there is a module of PP2Cs-BIN2-SnRK2s in the ABA signaling pathway.Collectively,these findings provide significant insights into how plants balance growth and survival by coordinately regulating the growth-promoting signaling pathway and stress responses under abiotic stresses.
URLPMID:25415975 [本文引用: 1]
Abstract Seed germination and postgerminative growth are regulated by a delicate hormonal balance. Abscisic acid (ABA) represses Arabidopsis thaliana seed germination and postgerminative growth, while brassinosteroids (BRs) antagonize ABA-mediated inhibition and promote these processes. However, the molecular mechanism underlying BR-repressed ABA signaling remains largely unknown. Here, we show that the Glycogen Synthase Kinase 3-like kinase BRASSINOSTEROID INSENSITIVE2 (BIN2), a critical repressor of BR signaling, positively regulates ABA responses during seed germination and postgerminative growth. Mechanistic investigation revealed that BIN2 physically interacts with ABSCISIC ACID INSENSITIVE5 (ABI5), a bZIP transcription factor. Further genetic analysis demonstrated that the ABA-hypersensitive phenotype of BIN2-overexpressing plants requires ABI5. BIN2 was found to phosphorylate and stabilize ABI5 in the presence of ABA, while application of epibrassinolide (the active form of BRs) inhibited the regulation of ABI5 by BIN2. Consistently, the ABA-induced accumulation of ABI5 was affected in BIN2-related mutants. Moreover, mutations of the BIN2 phosphorylation sites on ABI5 made the mutant protein respond to ABA improperly. Additionally, the expression of several ABI5 regulons was positively modulated by BIN2. These results provide evidence that BIN2 phosphorylates and stabilizes ABI5 to mediate ABA response during seed germination, while BRs repress the BIN2-ABI5 cascade to antagonize ABA-mediated inhibition. 2014 American Society of Plant Biologists. All rights reserved.
[本文引用: 1]
URLPMID:28363587 [本文引用: 1]
栽培大豆可以在驯服期间失去某有用基因 loci。从野大豆的基因的基因渗入能拓宽基因背景并且改进大豆农学的特点。在这研究，通过 recombinant 的整个染色体的定序，生来的线人口源于在野大豆 ZYD7 和栽培大豆 HN44 之间的一个十字，并且为种子重量量的特点 loci 印射，我们发现从野大豆 ZYD7 的磷酸酶 2C-1 ( PP2C-1 )等位基因在种子重量/尺寸贡献增加。PP2C-1 可以由提高覆盖物的房间尺寸并且激活一个子集完成这功能播种特点相关的基因。我们发现 PP2C-1 与 GmBZR1 被联系， Arabidopsis BZR1 的大豆 ortholog，之一在发信号的 brassinosteroid (BR ) 给抄写因素调音，并且便于 dephosphorylated GmBZR1 的累积。相反，有在 N 终点的一些氨基酸的变化的 PP2C-2 等位基因没展出这功能。而且，我们证明 GmBZR1 能在转基因的植物支持种子重量 / 尺寸。通过栽培大豆就职的分析，我们发现 40% 检验就职没有 PP2C-1 等位基因，建议这些就职能被这等位基因的介绍改进。一起拿，我们的学习识别精英等位基因 PP2C-1，它能在由分子帮助繁殖的这等位基因的那操作可以增加的大豆，和针尖提高种子重量或尺寸在大豆的生产和另外的荚 / 庄稼。
URLPMID:28089951 [本文引用: 2]
冷应力是不利地影响植物生长和开发的一个主要环境因素。C 重复有约束力的 factor/DRE 绑定因素 1 (CBF/DREB1 ) 规章的串联被显示出在对的植物反应起重要作用的 transcriptional 冷。这里，我们证明发信号的 brassinosteroid (BR ) 的二个关键部件调制 Arabidopsis 植物的结冰忍耐。象 GSK3 一样 kinases 的 loss-of-function 异种在 BR 发信号包含了， bin2-3 bil1 bil2，显示出的增加的结冰公差，而 BIN2 的 overexpression 导致了超敏性到结冰，在 non-acclimated 和 acclimated 下面的应力调节。由对比，显示的抄写因素 BZR1 和 BES1 的 gain-of-function 异种提高了结冰忍耐，和一致地冷的处理能导致 dephosphorylated BZR1 的累积。生物化学、基因的分析证明 BZR1 行动 CBF1 和 CBF2 到在上游直接调整他们的表示。而且，我们发现 BZR1 也调整了另外的英国管基因与 CBF 解开了例如 WKRY6， PYL6， SOC1， JMT，和 SAG21，种反应调制到冷应力。一致地， wrky6 异种显示出减少的结冰忍耐。一起拿，我们的结果显示 BZR1 断然调制通过 CBF 依赖、 CBF 独立的小径冻结忍耐的植物。
URLPMID:21258370 [本文引用: 1]
Abstract When brassinosteroid levels are low, the GSK3-like kinase BIN2 phosphorylates and inactivates the BZR1 transcription factor to inhibit growth in plants. Brassinosteroid promotes growth by inducing dephosphorylation of BZR1, but the phosphatase that dephosphorylates BZR1 has remained unknown. Here, using tandem affinity purification, we identified protein phosphatase 2A (PP2A) as a BZR1-interacting protein. Genetic analyses demonstrated a positive role for PP2A in brassinosteroid signalling and BZR1 dephosphorylation. Members of the B' regulatory subunits of PP2A directly interact with BZR1's putative PEST domain containing the site of the bzr1-1D mutation. Interaction with and dephosphorylation by PP2A are enhanced by the bzr1-1D mutation, reduced by two intragenic bzr1-1D suppressor mutations, and abolished by deletion of the PEST domain. This study reveals a crucial function for PP2A in dephosphorylating and activating BZR1 and completes the set of core components of the brassinosteroid-signalling cascade from cell surface receptor kinase to gene regulation in the nucleus.
URL [本文引用: 1]
URL [本文引用: 1]
Overall growth and development of a plant is regulated by complex interactions among various hormones, which is critical at different developmental stages. Some of the key aspects of plant growth include seed development, germination and plant survival under unfavorable conditions. Two of the key phytohormones regulating the associated physiological processes are gibberellins (GA) and abscisic acid (ABA). GAs participate in numerous developmental processes, including, seed development and seed germination, seedling growth, root proliferation, determination of leaf size and shape, flower induction and development, pollination and fruit expansion. Despite the association with abiotic stresses, ABA is essential for normal plant growth and development. It plays a critical role in different abiotic stresses by regulating various downstream ABA-dependent stress responses. Plants maintain a balance between GA and ABA levels constantly throughout the developmental processes at different tissues and organs, including under unfavorable environmental or physiological conditions. Here, we will review the literature on how GA and ABA control different stages of plant development, with focus on seed germination and selected abiotic stresses. The possible crosstalk of ABA and GA in specific events of the above processes will also be discussed, with emphasis on downstream stress signaling components, kinases and transcription factors (TFs). The importance of several key ABA and GA signaling intermediates will be illustrated. The knowledge gained from such studies will also help to establish a solid foundation to develop future crop improvement strategies.
URLPMID:22847438 [本文引用: 2]
Plant development is modulated by the convergence of multiple environmental and endogenous signals, and the mechanisms that allow the integration of different signaling pathways is currently being unveiled. A paradigmatic case is the concurrence of brassinosteroid (BR) and gibberellin (GA) signaling in the control of cell expansion during photomorphogenesis, which is supported by physiological observations in several plants but for which no molecular mechanism has been proposed. In this work, we show that the integration of these two signaling pathways occurs through the physical interaction between the DELLA protein GAI, which is a major negative regulator of the GA pathway, and BRASSINAZOLE RESISTANT1 (BZR1), a transcription factor that broadly regulates gene expression in response to BRs. We provide biochemical evidence, both in vitro and in vivo, indicating that GAI inactivates the transcriptional regulatory activity of BZR1 upon their interaction by inhibiting the ability of BZR1 to bind to target promoters. The physiological relevance of this interaction was confirmed by the observation that the dominant gai-1 allele interferes with BR-regulated gene expression, whereas the bzr1-1D allele displays enhanced resistance to DELLA accumulation during hypocotyl elongation. Because DELLA proteins mediate the response to multiple environmental signals, our results provide an initial molecular framework for the integration with BRs of additional pathways that control plant development.
PMID:26243314 [本文引用: 1]
Plant growth and development are highly regulated processes that are coordinated by hormones including the brassinosteroids (BRs), a group of steroids with structural similarity to steroid hormones of mammals. Although it is well understood how BRs are produced and how their signals are transduced, BR targets, which directly confer the hormone growth-promoting effects, have remained largely elusive. Here, we show that BRs regulate the biosynthesis of gibberellins (GAs), another class of growth-promoting hormones, in Arabidopsis thaliana. We reveal that Arabidopsis mutants deficient in BR signaling are severely impaired in the production of bioactive GA, which is correlated with defective GA biosynthetic gene expression. Expression of the key GA biosynthesis gene GA20ox1 in the BR signaling mutant bri1-301 rescues many of its developmental defects. We provide evidence that supports a model in which the BR-regulated transcription factor BES1 binds to a regulatory element in promoters of GA biosynthesis genes in a BR-induced manner to control their expression. In summary, our study underscores a role of BRs as master regulators of GA biosynthesis and shows that this function is of major relevance for the growth and development of vascular plants.
URLPMID:28818467 [本文引用: 1]
Abstract: The plant hormones brassinosteroid (BR) and gibberellin (GA) have important roles in a wide range of processes involved in plant growth and development. In this paper we derive and analyse new mathematical models for the BR signalling pathway and for the crosstalk between the BR and GA signalling pathways. To analyse the effects of spatial heterogeneity of the signalling processes, along with spatially-homogeneous ODE models we derive coupled PDE-ODE systems modelling the temporal and spatial dynamics of molecules involved in the signalling pathways. The values of the parameters in the model for the BR signalling pathway are determined using experimental data on the gene expression of BR biosynthetic enzymes. The stability of steady state solutions of our mathematical model, shown for a wide range of parameters, can be related to the BR homeostasis. Our results for the crosstalk model suggest that the interaction between transcription factors BZR and DELLA exerts more influence on the dynamics of the signalling pathways than BZR-mediated biosynthesis of GA, suggesting that the interaction between transcription factors may constitute the principal mechanism of the crosstalk between the BR and GA signalling pathways. In general, perturbations in the GA signalling pathway have larger effects on the dynamics of components of the BR signalling pathway than perturbations in the BR signalling pathway on the dynamics of the GA pathway. The perturbation in the crosstalk mechanism also has a larger effect on the dynamics of the BR pathway than of the GA pathway. Large changes in the dynamics of the GA signalling processes can be observed only in the case where there are disturbances in both the BR signalling pathway and the crosstalk mechanism.
URLPMID:22820377 [本文引用: 1]
Brassinosteroid and gibberellin promote many similar developmental responses in plants; however, their relationship remains unclear. Here we show that BR and GA act interdependently through a direct interaction between the BR-activated BZR1 and GA-inactivated DELLA transcription regulators. GA promotion of cell elongation required BR signalling, whereas BR or active BZR1 suppressed the GA-deficient dwarf phenotype. DELLAs directly interacted with BZR1 and inhibited BZR1-DNA binding both in vitro and in vivo. Genome-wide analysis defined a BZR1-dependent GA-regulated transcriptome, which is enriched with light-regulated genes and genes involved in cell wall synthesis and photosynthesis/chloroplast function. GA promotion of hypocotyl elongation requires both BZR1 and the phytochrome-interacting factors (PIFs), as well as their common downstream targets encoding the PRE-family helix-loop-helix factors. The results demonstrate that GA releases DELLA-mediated inhibition of BZR1, and that the DELLA-BZR1-PIF4 interaction defines a core transcription module that mediates coordinated growth regulation by GA, BR and light signals.
URLPMID:23033541 [本文引用: 1]
Abstract Plant growth and development are coordinated by several groups of small-molecule hormones, including brassinosteroids (BRs) and gibberellins (GAs). Physiological and molecular studies have suggested the existence of crosstalk between BR and GA signaling. We report that BZR1, a key transcription factor activated by BR signaling, interacts in vitro and in vivo with REPRESSOR OF ga1-3 (RGA), a member of the DELLA family of transcriptional regulators that inhibits the GA signaling pathway in Arabidopsis thaliana. Genetic analyses of plants with mutations in the genes encoding RGA and BZR1 revealed that RGA suppressed root and hypocotyl elongation of the gain-of-function mutant bzr1-1D. Ectopic expression of proteins of the DELLA family reduced the abundance and transcriptional activity of BZR1. Reporter gene analyses further indicated that BZR1 and RGA antagonize each other's transcriptional activity. Our data indicated that BZR1 and RGA served as positive and negative regulators, respectively, of both the BR and the GA signaling pathways and establish DELLAs as mediators of signaling crosstalk between BRs and GAs in controlling cell elongation and regulation of plant growth.
URLPMID:3909037 [本文引用: 1]
Brassinosteroids (BRs) and Gibberellins (GAs) are two principal groups of growth-promoting phytohormones. Accumulating evidence supports that there are crosstalks between BR and GA signaling pathways. However, a molecular mechanism for direct signaling crosstalk between BRs and GAs was not revealed until recently. Works from three different groups demonstrated that an interaction between BZR1/BES1 and DELLAs, two groups of key transcriptional regulators from the BR and GA signaling pathways, respectively, mediates the direct signaling crosstalk between BRs and GAs in controlling cell elongation in Arabidopsis. It was shown that DELLA proteins not only affect the protein stability but also inhibit the transcriptional activity of BZR1. Thus, GAs promote cell elongation, at least in part, through releasing DELLA-mediated inhibition of BZR1. This review aims to introduce these recent advances in our understanding of how BRs and GAs coordinate to regulate plant growth and development at the molecular level.
URLPMID:25371548 [本文引用: 1]
Brassinosteroid (BR) and gibberellin (GA) are two predominant hormones regulating plant cell elongation. A defect in either of these leads to reduced plant growth and dwarfism. However, their relationship remains unknown in rice (Oryza sativa). Here, we demonstrated that BR regulates cell elongation by modulating GA metabolism in rice. Under physiological conditions, BR promotes GA accumulation by regulating the expression of GA metabolic genes to stimulate cell elongation. BR greatly induces the expression of D18/GA3ox-2, one of the GA biosynthetic genes, leading to increased GA1 levels, the bioactive GA in rice seedlings. Consequently, both d18 and loss-of-function GA-signaling mutants have decreased BR sensitivity. When excessive active BR is applied, the hormone mostly induces GA inactivation through upregulation of the GA inactivation gene GA2ox-3 and also represses BR biosynthesis, resulting in decreased hormone levels and growth inhibition. As a feedback mechanism, GA extensively inhibits BR biosynthesis and the BR response. GA treatment decreases the enlarged leaf angles in plants with enhanced BR biosynthesis or signaling. Our results revealed a previously unknown mechanism underlying BR and GA crosstalk depending on tissues and hormone levels, which greatly advances our understanding of hormone actions in crop plants and appears much different from that in Arabidopsis thaliana.
URLPMID:5041101 [本文引用: 1]
Abstract Fruit ripening is a complex and genetically programmed process. Brassinosteroids (BRs) play an essential role in plant growth and development, including fruit ripening. As a central component of BR signaling, the transcription factor BZR1 is involved in fruit development in tomato. However, the transcriptional network through which BZR1 regulates fruit ripening is mostly unknown. In this study, we use isobaric tags for relative and absolute quantitation (iTRAQ) labeling technology to explore important proteins regulated by BZR1 in two independent tomato transgenic lines over-expressing BZR1-1D at four ripening stages, identifying 411 differentially expressed proteins. These proteins were implicated in light reaction, plant hormone pathways and cell-wall-related metabolism, etc. The 'light reaction' metabolic pathway was identified as a markedly enhanced pathway by BZR1 during tomato fruit ripening. The protein level of a probable 2-oxoglutarate-dependent dioxygenase 2-ODD2, involved in gibberellin biosynthesis was significantly increased at all four developmental and ripening stages. The results reveal molecular links between BR signaling pathway and downstream components involved in multiple ripening-associated events during tomato fruit ripening, which will provide new insights into the molecular mechanisms underlying tomato ripening regulatory networks, and be potential in understanding BR-regulated fruit ripening.
URL [本文引用: 1]
Abstract Genetic improvement of plant architecture is one of the strategies for increasing the yield potential of rice (Oryza sativa). Although great progress has been made in the understanding of plant architecture regulation, the precise mechanism is still an urgent need to be revealed. Here, we report that over-expression of OsMIR396d in rice results in semi-dwarf and increased leaf angle, a typical phenotype of BR enhanced mutant. OsmiR396d is involved in the interaction network of BR and GA signal. In OsMIR396d over-expression plants, BR signaling was enhanced. In contrast, both the signaling and biosynthesis of GA were impaired. BRASSINAZOLE-RESISTANT1 (OsBZR1), a core transcription activator of BR signaling, directly promoted the accumulation of OsmiR396d which controlled BR response and GA biosynthesis by regulating the expression of different target genes respectively. GROWTH REGULATING FACTOR 6 (OsGRF6), one of OsmiR396d targets, participated in GA biosynthesis and signal transduction, but was not directly involved in BR signaling. This study provides a new insight into the understanding of interaction between BR and GA from multiple levels on controlling plant architecture.
URL [本文引用: 1]
URLPMID:3022420 [本文引用: 1]
Light and brassinosteroid (BR) antagonistically regulate the developmental switch from etiolation in the dark to photomorphogenesis in the light in plants. Here, we identify GATA2 as a key transcriptional regulator that mediates the crosstalk between BR- and light-signaling pathways. Overexpression of GATA2 causes constitutive photomorphogenesis in the dark, whereas suppression of GATA2 reduces photomorphogenesis caused by light, BR deficiency, or the constitutive photomorphogenesis mutant . Genome profiling and chromatin immunoprecipitation experiments show that GATA2 directly regulates genes that respond to both light and BR. BR represses Graphical AbstractView high quality image (189K)
URLPMID:26363272 [本文引用: 3]
The BR-activated transcription factor BZR1 interacts with the light-activated transcription factor HY5 to mediate BR- and light-regulated cotyledon opening inArabidopsisin darkness. HY5 hampers BZR1 protein accumulation and binds the dephosphorylated active form of BZR1 to attenuate its transcriptional activity in regulating the expression of genes involved in cotyledon development and opening.
URLPMID:21852137 [本文引用: 1]
As they emerge from the ground, seedlings adopt a photosynthetic lifestyle, which is accompanied by dramatic changes in morphology and global alterations in gene expression that optimizes the plant body plan for light capture. Phytochromes are red and far-red photoreceptors that play a major role during photomorphogenesis, a complex developmental program that seedlings initiate when they first encounter light. The earliest phytochrome signaling events after excitation by red light include their rapid translocation from the cytoplasm to subnuclear bodies (photobodies) that contain other proteins involved in photomorphogenesis, including a number of transcription factors and E3 ligases. In the light, phytochromes and negatively acting transcriptional regulators that interact directly with phytochromes are destabilized, whereas positively acting transcriptional regulators are stabilized. Here, we discuss recent advances in our knowledge of the mechanisms linking phytochrome photoactivation in the cytoplasm and transcriptional regulation in the nucleus.
URLPMID:3019249 [本文引用: 1]
A small subset of basic helix–loop–helix transcription factors called PIFs (phytochrome-interacting factors) act to repress seed germination, promote seedling skotomorphogenesis and promote shade-avoidance through regulated expression of over a thousand genes. Light-activated phytochrome molecules directly reverse these activities by inducing rapid degradation of the PIF proteins. Here, we review recent advances in dissecting this signaling pathway and examine emerging evidence that indicates that other pathways also converge to regulate PIF activity, including the gibberellin pathway, the circadian clock and high temperature. Thus PIFs have broader roles than previously appreciated, functioning as a cellular signaling hub that integrates multiple signals to orchestrate regulation of the transcriptional network that drives multiple facets of downstream morphogenesis. The relative contributions of the individual PIFs to this spectrum of regulatory functions ranges from quantitatively redundant to qualitatively distinct.
URLPMID:29337075 [本文引用: 1]
Thermomorphogenesis is defined as the suite of morphological changes that together are likely to contribute to adaptive growth acclimation to usually elevated ambient temperature [ 1 ; 2 ]. While many details of warmth-induced signal transduction are still elusive, parallels to light signaling recently became obvious (reviewed in [ 3 ]). It involves photoreceptors that can also sense changes in ambient temperature [ 3 ; 4 ; 5 ] and act, for example, by repressing protein activity of the central integrator of temperature information PHYTOCHROME-INTERACTING FACTOR 4 (PIF4 [ 6 ]). In addition, PIF4 transcript accumulation is tightly controlled by the evening complex member EARLY FLOWERING 3 [ 7 ; 8 ]. According to the current understanding, PIF4 activatesgrowth-promoting genes directly but also via inducing auxin biosynthesis and signaling, resulting in cell elongation. Based on a mutagenesis screen in the model plant Arabidopsis thaliana for mutants with defects in temperature-induced hypocotyl elongation, we show here that both PIF4 and auxin function depend onbrassinosteroids. Genetic and pharmacological analyses place brassinosteroids downstream of PIF4 and auxin. We found that brassinosteroids actviathe transcription factor BRASSINAZOLE RESISTANT 1 (BZR1), which accumulates in the nucleus at hightemperature, where it induces expression of growth-promoting genes. Furthermore, we show that at elevated temperature BZR1 binds to the promoter of PIF4 , inducing its expression. These findings suggest that BZR1 functions in an amplifying feedforward loop involved in PIF4 activation. Although numerous negative regulators of PIF4 have been described, we identify BZR1 here as a true temperature-dependent positive regulator of PIF4 , acting as a major growth coordinator.
URLPMID:29398622 [本文引用: 1]
UV-B light (UV-B radiation) is known to inhibit plant growth, but the mechanism is not well understood. UVR8 (UV RESISTANCE LOCUS 8) is a UV-B light photoreceptor that mediates UV-B light responses in plants. We report here that UV-B inhibits plant growth by repressing plant steroid hormone brassinosteroid (BR)-promoted plant growth. UVR8 physically interacts with the functional dephosphorylated BES1 (BRI1-EMS-SUPPRESSOR1) and BIM1 (BES1-INTERACTING MYC-LIKE 1) transcription factors that mediate BR-regulated gene expression and plant growth to inhibit their activities. Genome-wide gene expression analysis defined a BES1-dependent UV-B-regulated transcriptome, which is enriched with genes involved in cell elongation and plant growth. We further showed that UV-B-activated and nucleus-localized UVR8 inhibited the DNA-bindingactivities of BES1/BIM1 to directly regulate transcription of growth-related genes. Our results therefore establish that UVR8-BES1/BIM1 interaction represents an early photoreceptor signaling mechanism in plants and serves as an important module integrating light and BR signaling.
[本文引用: 1]
URLPMID:5408700 [本文引用: 1]
Light and brassinosteroid (BR) are master environmental stimulus and endogenous cue for plant growth and development respectively. Great progress has been made in elucidating the molecular mechanisms on the cross-talk between light and BR. However, little is known about how BZR1, the pivotal integration node, is regulated by light and dark. Here, we demonstrated that an intact BR signaling pathway is essential for dark-induced hypocotyl elongation. Consequent expression assay showed that light ark switch affected BZR1 phosphorylation and accumulation. Moreover, blocking the 26S proteasome pathway promoted the accumulation of both phosphorylated and dephosphorylated BZR1 proteins. Restriction of new protein biosynthesis had multiple effects on BZR1 phosphorylation status and stability, relying on the availability of light and the 26S proteasome pathways. Furthermore, sugar treatment strikingly enhanced the accumulation of total BZR1 under either light or dark conditions, likely by repressing transcript abundance ofMAX2, a gene encoding an E3 ligase for BZR1. Finally, light-regulated phosphorylation change of BZR1 requires the existence of endogenous BR as well as functional BIN2 and protein phosphatase 2A (PP2A). Taken together, our results depicted a light-involved complex regulation network of BZR1 stability and phosphorylation status.
URLPMID:24387668 [本文引用: 2]
Light is essential for plant survival; as such, plants flexibly adjust their growth and development to best harvest light energy. Brassinosteroids (BRs), plant growth-promoting steroid hormones, are essential for this plasticity of development. However, the precise mechanisms underlying BR-mediated growth under different light conditions remain largely unknown. Here, we show that darkness increases the activity of the BR-specific transcription factor, BZR1, by decreasing the phosphorylated (inactive) form of BZR1 in a proteasome-dependent manner. We observed that COP1, a dark-activated ubiquitin ligase, captures and degrades the inactive form of BZR1. In support of this, BZR1 is abundant in the cop1-4 mutant. The removal of phosphorylated BZR1 in darkness increases the ratio of dephosphorylated to phosphorylated forms of BZR1, thus increasing the chance of active homodimers forming between dephosphorylated BZR1 proteins. Furthermore, a transcriptome analysis revealed the identity of genes that are likely to contribute to the differential growth of hypocotyls in light conditions. Transgenic misexpression of three genes under the 35S promoter in light conditions resulted in elongated petioles and hypocotyls. Our results suggest that light conditions directly control BR signaling by modulating BZR1 stability, and consequently by establishing light-dependent patterns of hypocotyl growth in Arabidopsis.
URL [本文引用: 1]
react-text: 343 Transient grating signals after photoexcitation of Arabidopsis phototropin 1 light-oxygen-voltage 2 (phot1LOV2) domain without the linker were found to be very sensitive to temperature. In particular, the diffusion signal drastically increased with rising temperature. The signal was consistently explained by the superposition of the photo-induced dissociation and association reactions. This... /react-text react-text: 344 /react-text [Show full abstract]
URLPMID:23580754 [本文引用: 1]
The effect of 24-epibrassinolide (EBR) on glucosinolate biosynthesis in Arabidopsis thaliana was investigated in the present study by using mutants and transgenic plants involved in brassinosteroid (BR) biosynthesis and signal transduction, as well as glucosinolate biosynthesis. The results showed that EBR significantly decreased the contents of major aliphatic glucosinolates including glucoiberin (S3), glucoraphanin (S4), and glucoerucin (T4), as well as the indolic glucosinolates glucobrassicin (IM) and neoglucobrassicin (1IM). In addition, a significantly higher level of glucosinolates accumulated in the BR-deficient mutant cpd and a dramatically lower glucosinolate content in the transgenic plant DWF4-ox overexpressing the BR biosynthetic gene DWF4 compared with their related wild-types, confirmed the repressing effect of BR on glucosinolate biosynthesis. BRI1, the receptor of BR signal transduction, was involved in regulation of glucosinolate biosynthesis by BR. Furthermore, the observation of reduced content of glucosinolates and lower expression levels of glucosinolate biosynthetic genes in 35S-BZR1/bzr1-1D and bes1-D plants compared with the corresponding wild-types suggested that BZR1 and BES1, two important components in BR signal transduction, are responsible for the inhibiting role of BR in glucosinolate biosynthesis. The disappearance of the repressing effect of BR on glucosinolate content in the myb28, myb34, and myb122 mutants indicated that these three MYB factors are important for the regulation of BR in glucosinolate biosynthesis.
URLPMID:25036120 [本文引用: 1]
The plant steroid hormones brassinosteroids (BRs) play important roles in plant growth and responses to stresses. The up-regulation of pathogen resistance by BR signaling has been analyzed, but the relationship between BR and insect herbivores remains largely unclear. BIL1/BZR1 is a BR master transcription factor known to be involved in the regulation of plant development through work conducted on a gain of function mutation. Here, we analyzed the function of BIL1/BZR1 in response to insect feeding and demonstrated that resistance against thrip feeding was increased in the bil1-1D/bzr1-1D mutant compared to wild-type. We generated Lotus japonicus transgenic plants that over-express the Arabidopsis bil1/bzr1 mutant, Lj-bil1/bzr1-OX. The Lj-bil1/bzr1-OX plants showed increased resistance to thrip feeding. The expression levels of the jasmoninc acid (JA)-inducible VSP genes were increased in both Arabidopsis bil1-1D/bzr1-1D mutants and L. japonicus Lj-bil1/bzr1-OX plants. The resistance to thrip feeding caused by the BIL1/BZR1 gene may involve JA signaling.
[本文引用: 1]
URL [本文引用: 1]
Plants feature remarkable developmental plasticity, enabling them to respond to and cope with environmental cues, such as limited availability of phosphate, an essential macronutrient for all organisms. Under this condition, Arabidopsis (Arabidopsis thaliana) roots undergo striking morphological changes, including exhaustion of the primary meristem, impaired unidirectional cell expansion, and elevated density of lateral roots, resulting in shallow root architecture. Here, we show that the activity of two homologous brassinosteroid (BR) transcriptional effectors, BRASSINAZOLE RESISTANT1 (BZR1) and BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1 (BES1)/BZR2, blocks these responses, consequently maintaining normal root development under low phosphate conditions without impacting phosphate homeostasis. We show that phosphate deprivation shifts the intracellular localization of BES1/BZR2 to yield a lower nucleus-to-cytoplasm ratio, whereas replenishing the phosphate supply reverses this ratio within hours. Phosphate deprivation reduces the expression levels of BR biosynthesis genes and the accumulation of the bioactive BR 28-norcastasterone. In agreement, low and high BR levels sensitize and desensitize root response to this adverse condition, respectively. Hence, we propose that the environmentally controlled developmental switch from deep to shallow root architecture involves reductions in BZR1 and BES1/BZR2 levels in the nucleus, which likely play key roles in plant adaptation to phosphate-deficient environments.
URLPMID:28576847 [本文引用: 1]
Plant steroid hormones, brassinosteroids (BRs), play important roles in growth and development. BR signaling controls the activities of BRASSINOSTERIOD INSENSITIVE1-EMS-SUPPRESSOR1/BRASSINAZOLE-RESISTANT1 (BES1/BZR1) family transcription factors. Besides the role in promoting growth, BRs are also implicated in plant responses to drought stress. However, the molecular mechanisms by which BRs regulate drought response have just begun to be revealed. The functions of WRKY transcription factors in BR-regulated plant growth have not been established, although their roles in stress responses are well documented. Here, we found that three Arabidopsis thaliana group III WRKY transcription factors, WRKY46, WRKY54, and WRKY70, are involved in both BR-regulated plant growth and drought response as the wrky46 wrky54 wrky70 triple mutant has defects in BR-regulated growth and is more tolerant to drought stress. RNA-sequencing analysis revealed global roles of WRKY46, WRKY54, and WRKY70 in promoting BR-mediated gene expression and inhibiting drought responsive genes. WRKY54 directly interacts with BES1 to cooperatively regulate the expression of target genes. In addition, WRKY54 is phosphorylated and destabilized by GSK3-like kinase BR-INSENSITIVE2, a negative regulator in the BR pathway. Our results therefore establish WRKY46/54/70 as important signaling components that are positively involved in BR-regulated growth and negatively involved in drought responses.
URLPMID:28233777 [本文引用: 1]
Brassinosteroids (BRs) regulate plant growth and stress responses via the BES1/BZR1 family of transcription factors, which regulate the expression of thousands of downstream genes. BRs are involved in the response to drought, however the mechanistic understanding of interactions between BR signalling and drought response remains to be established. Here we show that transcription factor RD26 mediates crosstalk between drought and BR signalling. When overexpressed, BES1 target gene RD26 can inhibit BR-regulated growth. Global gene expression studies suggest that RD26 can act antagonistically to BR to regulate the expression of a subset of BES1-regulated genes, thereby inhibiting BR function. We show that RD26 can interact with BES1 protein and antagonize BES1 transcriptional activity on BR-regulated genes and that BR signalling can also repress expression of RD26 and its homologues and inhibit drought responses. Our results thus reveal a mechanism coordinating plant growth and drought tolerance.
URLPMID:5720862 [本文引用: 1]
Plants encounter a variety of stresses and must fine-tune their growth and stress-response programs to best suit their environment. BES1 functions as a master regulator in the brassinosteroid (BR) pathway that promotes plant growth. Here, we show that BES1 interacts with the ubiquitin receptor protein DSK2 and is targeted to the autophagy pathway during stress via the interaction of DSK2 with ATG8, a ubiquitin-like protein directing autophagosome formation and cargo recruitment. Additionally, DSK2 is phosphorylated by the GSK3-like kinase BIN2, a negative regulator in the BR pathway. BIN2 phosphorylation of DSK2 flanking its ATG8 interacting motifs (AIMs) promotes DSK2-ATG8 interaction, thereby targeting BES1 for degradation. Accordingly, loss-of-function dsk2 mutants accumulate BES1, have altered global gene expression profiles, and have compromised stress responses. Our results thus reveal that plants coordinate growth and stressresponses by integrating BR and autophagy pathways and identify the molecular basis of this crosstalk.
URLPMID:24867218 [本文引用: 1]
10.7554/eLife.03031.001As the major mechanism of plant growth and morphogenesis, cell elongation is controlled by many hormonal and environmental signals. How these signals are coordinated at the molecular level to ensure coherent cellular responses remains unclear. In this study, we illustrate a molecular circuit that integrates all major growth-regulating signals, including auxin, brassinosteroid, gibberellin, light, and temperature. Analyses of genome-wide targets, genetic and biochemical interactions demonstrate that the auxin-response factor ARF6, the light/temperature-regulated transcription factor PIF4, and the brassinosteroid-signaling transcription factor BZR1, interact with each other and cooperatively regulate large numbers of common target genes, but their DNA-binding activities are blocked by the gibberellin-inactivated repressor RGA. In addition, a tripartite HLH/bHLH module feedback regulates PIFs and additional bHLH factors that interact with ARF6, and thereby modulates auxin sensitivity according to developmental and environmental cues. Our results demonstrate a central growth-regulation circuit that integrates hormonal, environmental, and developmental controls of cell elongation in Arabidopsis hypocotyl.DOI: http://dx.doi.org/10.7554/eLife.03031.001
URLPMID:29897568 [本文引用: 1]
Hypocotyl cell elongation related to photomorphogenesis in Arabidopsis seedlings is regulated by a network involving ethylene, auxin, and brassinosteroid signalling that is mediated by interactions among ERF72, ARF6, and BZR1, forming a revised BZR-ARF-PIF/DELLA-ERF (BAP/DE) module. The phytohormones brassinosteroid (BR), auxin, and gibberellin (GA) regulate photomorphogenesis-related hypocotyl elongation in Arabidopsis via the co-operative interaction of BZR-ARF-PIF/DELLA (BAP/D) transcription factors/regulators. In addition, ethylene activates the PIF3 or ERF1 pathway through EIN3/EIL1 to balance hypocotyl elongation in Arabidopsis seedlings. However, the mechanism by which ethylene is co-ordinated with other phytohormones to produce light-regulated hypocotyl growth remains elusive. In this study, we found that hypocotyl cell elongation is regulated by a network involving ethylene, auxin, and BR signalling, which is mediated by interactions among ERF72, ARF6, and BZR1. ERF72 interacted directly with ARF6 and BZR1in vitroandin vivo, and it antagonised regulation by ARF6 and BZR1 of the transcription ofBEE3andXTH7. In addition, light modulated the subcellular localisation of ERF72 and transcription ofERF72through the EIN2-EIN3/EIL1 pathway, facilitating the function of ERF72 in photomorphogenesis. The expression ofBEE3andXTH7was also regulated by the EIN2-EIN3/EIL1 pathway. Our findings indicate that a revised BZR-ARF-PIF/DELLA-ERF (BAP/DE) module integrates light and hormone signals to regulate hypocotyl elongation in Arabidopsis.
