Characterization of the β-Carotene Hydroxylase Gene DSM2 Conferring Drought and Oxidative Stress Resistance by Increasing Xanthophylls and Abscisic Acid Synthesis in Rice
Characterization of the β-Carotene Hydroxylase Gene DSM2 Conferring Drought and Oxidative Stress Resistance by Increasing Xanthophylls and Abscisic Acid Synthesis in Rice
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DOI：
10.1104/pp.110.163741
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发表时间：
2010-11-01
期刊：
影响因子：
7.4
通讯作者：
Xiong, Lizhong
中科院分区：
文献类型：
--
作者：
Du, Hao;Wang, Nili;Xiong, Lizhong
干旱是限制作物生产的主要因素。为了鉴定水稻抗旱性的关键基因，我们筛选了T-DNA突变体，并鉴定了一个干旱超敏突变体dsm 2。突变表型是由T-DNA插入编码推定的β-胡萝卜素羟化酶（BCH）的基因引起的。预计BCH用于玉米黄质（脱落酸（阿坝）的类胡萝卜素前体）的生物合成。与野生型相比，干旱胁迫后两个等位基因dsm 2突变体的玉米黄质和阿坝的量显着降低。在干旱胁迫条件下，突变体叶片失水速度比野生型快，光合速率、生物量和籽粒产量显著降低，丙二醛含量和气孔开度增加。该突变体对氧化应激也高度敏感。突变体的光系统II光化学和非光化学猝灭能力的最大效率显着低于野生型，表明光抑制在光系统II和减少的能力，消除多余的能量通过热耗散。在水稻中过表达DSM 2导致对干旱和氧化胁迫的抗性显着增加，叶黄素和非光化学猝灭的增加。一些胁迫相关的ABA反应基因在过表达系中表达上调。DSM 2是一种叶绿体蛋白，它对环境刺激的反应与水稻中的其他两个BCH成员不同。我们的结论是，DSM 2基因显着有助于控制叶黄素循环和阿坝的合成，这两个在水稻抗旱性的建立起关键作用。
Drought is a major limiting factor for crop production. To identify critical genes for drought resistance in rice (Oryza sativa), we screened T-DNA mutants and identified a drought-hypersensitive mutant, dsm2. The mutant phenotype was caused by a T-DNA insertion in a gene encoding a putative beta-carotene hydroxylase (BCH). BCH is predicted for the biosynthesis of zeaxanthin, a carotenoid precursor of abscisic acid (ABA). The amounts of zeaxanthin and ABA were significantly reduced in two allelic dsm2 mutants after drought stress compared with the wild type. Under drought stress conditions, the mutant leaves lost water faster than the wild type and the photosynthesis rate, biomass, and grain yield were significantly reduced, whereas malondialdehyde level and stomata aperture were increased in the mutant. The mutant is also hypersensitive to oxidative stresses. The mutant had significantly lower maximal efficiency of photosystem II photochemistry and nonphotochemical quenching capacity than the wild type, indicating photoinhibition in photosystem II and decreased capacity for eliminating excess energy by thermal dissipation. Overexpression of DSM2 in rice resulted in significantly increased resistance to drought and oxidative stresses and increases of the xanthophylls and nonphotochemical quenching. Some stress-related ABA-responsive genes were up-regulated in the overexpression line. DSM2 is a chloroplast protein, and the response of DSM2 to environmental stimuli is distinctive from the other two BCH members in rice. We conclude that the DSM2 gene significantly contributes to control of the xanthophyll cycle and ABA synthesis, both of which play critical roles in the establishment of drought resistance in rice.