余斌^1,2,3, 杨佳丽^1,2,3, 牛建峰^1,4,3, 王广策^1,4,3
1.中国科学院海洋研究所实验海洋生物学重点实验室, 山东 青岛 266071;2.中国科学院大学, 北京 100049;3.中国科学院海洋大科学研究中心, 山东 青岛 266071;4.青岛海洋科学与技术国家实验室海洋生物与生物技术实验室, 山东 青岛 266237

摘要:
植物在逆境下产生活性氧，诱导抗氧化酶活性、抗逆基因表达上调。采用梯度盐度胁迫的方法处理条斑紫菜，发现高盐胁迫下细胞内脱落酸（ABA）含量随盐度的增加而增加，提示条斑紫菜中可能存在ABA介导的抗氧化代谢通路。利用ABA间接合成途径相关的几种抑制剂处理条斑紫菜叶状体，高盐胁迫诱导氧自由基产生，在藻体复苏过程中通过测定光合作用参数的恢复情况，探测藻体受到的氧化伤害，从而证明条斑紫菜中ABA生物合成的可能路径。结果显示多效唑显著降低了光系统Ⅱ的电子传递能力，说明条斑紫菜中C5前体的合成是通过类似真菌的MVA途径；萘普生减缓了光合参数的恢复，说明条斑紫菜中ABA合成途径类似于类胡萝卜素参与的间接途径；然而，间接途径合成最后一步的抑制剂钨酸钠却没有影响条斑紫菜胁迫后光合作用参数的恢复，说明条斑紫菜中可能存在经由脱落醇生成ABA的支路途径，而脱落醇可作为活性分子，调控抗氧化酶的表达。烯唑醇则可能引起ABA的分解代谢受到抑制，导致过氧化氢的过度产生，并最终对机体产生不利影响。本文的结果为后续条斑紫菜ABA介导的抗氧化机制解析提供了数据支持。
关键词:脱落酸生物合成途径活性氧清除系统高盐胁迫植物激素光合作用
DOI：10.11759/hykx20180508001
分类号:
基金项目:国家自然科学基金项目（41776150，41476140）；现代农业产业技术体系专项（CARS-50）

Synthesis of abscisic acid in Pyropia yezoensis and its protection on photosynthesis under high-salinity stress
YU Bin^1,2,3, YANG Jia-li^1,2,3, NIU Jian-feng^1,4,3, WANG Guang-ce^1,4,3
1.Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.University of Chinese Academy of Sciences, Beijing 100049, China;3.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;4.Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266237, China
Abstract:
Active oxygen radicals are induced when a plant is subjected to environmental stress. The burst of ROS usually leads to gene upregulation related to stress response and an increase in antioxidase activity. Our results showed that the ABA content in high-salinity stressed Pyropia yezoensis presented a significant upregulation compared with that in the control. The results strongly suggested that there might be an antioxidant pathway mediated by ABA in P. yezoensis. To find the possible ABA synthesis pathway, the thallus of the algae was treated with inhibitors related to the carotenoid biosynthetic pathway of ABA. Then, the samples were stressed with 120‰ salinity to induce active oxygen radicals. The control was set as the same high-salinity treatment but without corresponding inhibitors. Based on the determination of ETR(Ⅱ) variation during rehydration, the potential effect of various inhibitors on ABA synthesis was side evaluated. The results showed that ETR(Ⅱ) was influenced obviously by the addition of paclobutrazol, indicating that the precursor of ABA synthesis was derived from C5 unit, which was similar to the MVA pathway in fungi. Naproxen could slow down the recovery of ETR(Ⅱ), which meant that the synthesis of ABA in P. yezoensis was through the indirect pathway. However, sodium tungstate, which was the inhibitor of the last step in the ABA carotenoid biosynthetic pathway, showed no influence on the recovery of ETR(Ⅱ), indicating that there might be a bypass pathway in which ABA was biosynthesized through abscisic alcohol, which has been reported as an active molecule with a function similar to that of ABA. Diniconazole repressed the decomposition of ABA, which led to excessive production of hydrogen peroxide, thereby causing damage to photosynthetic apparatus. The results provided data support for future investigation of the antioxidation mechanism mediated by ABA in P. yezoensis.
Key words:abscisic acidbiosynthetic pathwayreactive oxygen species scavenging systemhigh-salinity stressplant hormonephotosynthesis





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