Wang Zhen-Yu, Gehring Chris, Zhu Jianhua, Li Feng-Min, Zhu Jian-Kang, Xiong Liming
Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.).
Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.)
Plant Physiol. 2015 Jan;167(1):137-52. doi: 10.1104/pp.114.249268. Epub 2014 Nov 21.
Osmotic stress activates the biosynthesis of the phytohormone abscisic acid (ABA) through a pathway that is rate limited by the carotenoid cleavage enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). To understand the signal transduction mechanism underlying the activation of ABA biosynthesis, we performed a forward genetic screen to isolate mutants defective in osmotic stress regulation of the NCED3 gene. Here, we identified the Arabidopsis (Arabidopsis thaliana) Vacuolar Sorting Receptor1 (VSR1) as a unique regulator of ABA biosynthesis. The vsr1 mutant not only shows increased sensitivity to osmotic stress, but also is defective in the feedback regulation of ABA biosynthesis by ABA. Further analysis revealed that vacuolar trafficking mediated by VSR1 is required for osmotic stress-responsive ABA biosynthesis and osmotic stress tolerance. Moreover, under osmotic stress conditions, the membrane potential, calcium flux, and vacuolar pH changes in the vsr1 mutant differ from those in the wild type. Given that manipulation of the intracellular pH is sufficient to modulate the expression of ABA biosynthesis genes, including NCED3, and ABA accumulation, we propose that intracellular pH changes caused by osmotic stress may play a signaling role in regulating ABA biosynthesis and that this regulation is dependent on functional VSR1.
渗透胁迫通过一条由类胡萝卜素裂解酶9-顺式环氧类胡萝卜素双加氧酶（NCED）限速的途径激活植物激素脱落酸（ABA）的生物合成。为了理解ABA生物合成激活背后的信号转导机制，我们进行了一项正向遗传学筛选，以分离在NCED3基因渗透胁迫调控方面存在缺陷的突变体。在此，我们鉴定出拟南芥液泡分选受体1（VSR1）是ABA生物合成的一个独特调节因子。vsr1突变体不仅对渗透胁迫表现出更高的敏感性，而且在ABA对ABA生物合成的反馈调节方面存在缺陷。进一步分析表明，VSR1介导的液泡运输对于渗透胁迫响应的ABA生物合成和渗透胁迫耐受性是必需的。此外，在渗透胁迫条件下，vsr1突变体中的膜电位、钙通量和液泡pH变化与野生型不同。鉴于调节细胞内pH足以调节包括NCED3在内的ABA生物合成基因的表达以及ABA积累，我们提出渗透胁迫引起的细胞内pH变化可能在调节ABA生物合成中起信号作用，并且这种调节依赖于功能性的VSR1。
