Glutathione reductase in leaves of cowpea: Cloning of two cDNAs, expression and enzymatic activity under progressive drought stress, desiccation and abscisic acid treatment
Glutathione reductase in leaves of cowpea: Cloning of two cDNAs, expression and enzymatic activity under progressive drought stress, desiccation and abscisic acid treatment
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DOI：
10.1093/aob/mcl217
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发表时间：
2006-12-01
期刊：
影响因子：
4.2
通讯作者：
D'Arcy-Lameta, Agnes
中科院分区：
文献类型：
--
作者：
Contour-Ansel, Dominique;Torres-Franklin, Maria Lucia;D'Arcy-Lameta, Agnes
背景与目的植物在受到非生物胁迫时，经常会产生活性氧。在解毒系统中，抗坏血酸过氧化物酶和谷胱甘肽还原酶（GR）起关键作用。GR还在应激期间保持还原型谷胱甘肽池中起核心作用，从而允许对细胞氧化还原反应进行调节。以干旱胁迫、快速脱水和外源脱落酸（阿坝）处理的豇豆（Vigna unguiculata）为材料，研究干旱胁迫对豇豆叶片胞质和双靶GR基因表达的影响。将切下的叶片风干或用外源阿坝处理。通过PCR分离两个GR cDNA，一个是胞质的，另一个是叶绿体和线粒体双靶向的，并克隆到质粒载体中。关键结果从长爪葡萄叶片中克隆了两个新的GR基因cDNA，分别编码一个双靶GR和一个胞质GR，并进行了序列测定。干旱胁迫诱导的胞质GR基因的表达上调，直接关系到在两个品种的压力的强度。干旱处理仅上调了感病品种双靶GR的表达。在快速脱水下，‘1183’品种比‘EPACE-1’晚响应，尽管在‘EPACE-1’中响应的是胞质异构体，而在‘1183’中是双靶向异构体。外源阿坝处理24 h后，在两个品种的GR的活性和表达水平显着增强。结论这些结果表明，在两个品种的抗氧化代谢的一个渐进的水分胁迫下，这涉及两个GR基因的情况下，敏感品种显着激活。在快速脱水条件下，感病品种的响应晚于抗病品种，说明感病品种的响应能力弱于抗病品种。外源阿坝可能通过介导的信号转导途径影响GR基因的表达。
Background and Aims Reactive oxygen species are frequently produced when plants are exposed to abiotic stresses. Among the detoxication systems, two enzymes, ascorbate peroxidase and glutathione reductase (GR) play key roles. GR has also a central role in keeping the reduced glutathione pool during stress thus allowing the adjustments on the cellular redox reactions. The aim of this work was to study the variations in cytosolic and dual-targeted GR gene expression in the leaves of cowpea plants submitted to progressive drought, rapid desiccation and application of exogenous abscisic acid (ABA).Methods Two cowpea (Vigna unguiculata) cultivars, one drought-resistant ('EPACE-1'), the other drought-sensitive ('1183') were submitted to progressive drought stress by withholding irrigation. Cut-off leaves were air-dried or treated with exogenous ABA. Two GR cDNAs, one cytosolic, the other dual-targeted to chloroplasts and mitochondria were isolated by PCR and cloned in plasmid vectors. Reverse-transcription PCR was used to study the variations in GR gene expression.Key Results Two new cDNAs encoding a putative dual-targeted and a cytosolic GR were cloned and sequenced from leaves of V. unguiculata. Drought stress induced an up-regulation of the expression of the cytosolic GR gene directly related to the intensity of the stress in both cultivars. The expression of dual-targeted GR was up-regulated by the drought treatment in the susceptible cultivar only. Under a fast desiccation, the '1183' cultivar responded later than the 'EPACE-1', although in 'EPACE-1' it was the cytosolic isoform which responded and in '1183' the dual-targeted one. Exogenous ABA enhanced significantly the activity and expression levels of GR in both cultivars after treatment for 24 h.Conclusions These results demonstrate a noticeable activation in both cultivars of the antioxidant metabolism under a progressive water stress, which involves both GR genes in the case of the susceptible cultivar. Under a fast desiccation, the susceptible cultivar responded later than the resistant one, suggesting a weaker capacity of response versus the resistant one. Exogenous ABA probably acts on GR gene expression via a mediated signal transduction pathway.