Peng Qin
Li Hu
Shijie Zhan
Shifu Wang
Peng Gao
Jing Li
Mengya Jin
Zhengyan Xu
Qiang Gao
Anping Du
Bin Tu
Weilan Chen
Bingtian Ma
Yuping Wang
Shigui Li
aRice Research Institute, Sichuan Agricultural University, Wenjiang, 611130, China
bState Key Laboratory of Hybrid Rice, Sichuan Agricultural University, Wenjiang, 611130, China
cStation of Foundation and Improved Seed-breeding of Sichuan Province, Shuangliu, 610200, China
dState Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
More InformationCorresponding author: E-mail address: lishigui@sicau.edu.cn (Shigui Li)
Received Date: 2018-11-07
Accepted Date:2019-01-20
Rev Recd Date:2018-12-24
Available Online: 2019-01-23 Publish Date:2019-01-20
Abstract
Abstract
Grain weight and grain number are two important traits directly determining grain yield in rice. To date, a lot of genes related to grain weight and grain number have been identified; however, the regulatory mechanism underlying these genes remains largely unknown. In this study, we studied the biological function of OsSPL18 during grain and panicle development in rice. Knockout (KO) mutants of OsSPL18 exhibited reduced grain width and thickness, panicle length and grain number, but increased tiller number. Cytological analysis showed that OsSPL18 regulates the development of spikelet hulls by affecting cell proliferation. qRT-PCR and GUS staining analyses showed that OsSPL18 was highly expressed in developing young panicles and young spikelet hulls, in agreement with its function in regulating grain and panicle development. Transcriptional activation experiments indicated that OsSPL18 is a functional transcription factor with activation domains in both the N-terminus and C-terminus, and both activation domains are indispensable for its biological functions. Quantitative expression analysis showed that DEP1, a major grain number regulator, was significantly down-regulated in OsSPL18 KO lines. Both yeast one-hybrid and dual-luciferase (LUC) assays showed that OsSPL18 could bind to the DEP1 promoter, suggesting that OsSPL18 regulates panicle development by positively regulating the expression of DEP1. Sequence analysis showed that OsSPL18 contains the OsmiR156k complementary sequence in the third exon; 5? RLM-RACE experiments indicated that OsSPL18 could be cleaved by OsmiR156k. Taken together, our results uncovered a new OsmiR156k-OsSPL18-DEP1 pathway regulating grain number in rice.Keywords: Grain weight,
Grain number,
Rice
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