Comparison of hormonal responses to heat, drought and combined stress in tobacco plants with elevated proline content
Comparison of hormonal responses to heat, drought and combined stress in tobacco plants with elevated proline content
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DOI：
10.1016/j.jplph.2010.05.013
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发表时间：
2010-01-01
影响因子：
4.3
通讯作者：
Vankova, Radomira
中科院分区：
文献类型：
--
作者：
Dobra, Jana;Motyka, Vaclav;Vankova, Radomira
为了测试提高耐热性和耐旱性的可能性在组成型过表达脯氨酸生物合成酶δ（2）-吡咯啉-5-羧酸合成酶基因的烟草植物中比较了通过提高植物保护剂脯氨酸（Pro）含量（单独和组合）的胁迫反应（P5 CSF 129 A EC 2 7 2 11/1 2 1 41）和相应的野生型中显著增强的Pro产生与更负的叶片渗透势相一致（在对照条件和随后的胁迫下）和增强的保护性叶黄素循环色素的产生热胁迫（40 ℃）引起生物活性细胞分裂素水平的短暂增加，主要是N-6-（2-异戊烯基）腺苷伴随着主要细胞分裂素降解酶细胞分裂素氧化酶/脱氢酶活性的下调（EC 1 43 18/1 5 99 12）所测试的基因型之间没有发现显着差异。同时，在干旱胁迫后，观察到脱落酸的短暂减少，整个植物的生物活性细胞分裂素水平下降，在优先保护的上部叶和根部中保持相对较高的细胞分裂素抑制在Pro中不太明显热应激在10 d干旱期结束时，40 ℃处理2 h，可显著增强水分胁迫的严重程度，表现为叶水势下降。在整个植物中生物活性细胞分裂素的调节高温和干旱联合胁迫导致脱落酸的轻微下降，但仅在非两种胁迫及其组合均与下部叶片中游离生长素吲哚乙酸的升高有关，再水化后，观察到叶片中生物活性细胞分裂素的显著增加。Pro转化体中细胞分裂素含量的较大增加表明其细胞分裂素含量的轻度增加。应力耐受性（C）2010 Elsevier GmbH版权所有
In order to test the possibility of improving tolerance to heat and drought (alone and in combination) by elevation of the osmoprotectant proline (Pro) content stress responses were compared in tobacco plants constitutively over-expressing a gene for the Pro biosynthetic enzyme Delta(2)-pyrroline-5-carboxylate synthetase (P5CSF129A EC 2 7 2 11/1 2 1 41) and in the corresponding wild-type Significantly enhanced Pro production in the transformant coincided with a more negative leaf osmotic potential (both at control conditions and following stress) and enhanced production of protective xanthophyll cycle pigments Heat stress (40 C) caused a transient increase in the level of bioactive cytokinins predominantly N-6-(2-isopentenyl)adenosine accompanied by down-regulation of the activity of the main cytokinin degrading enzyme cytokinin oxidase/dehydrogenase (EC 1 43 18/1 5 99 12) No significant differences were found between the tested genotypes In parallel a transient decrease of abscisic acid was observed Following drought stress bioactive cytokinin levels decreased in the whole plants remaining relatively higher in preferentially protected upper leaves and in roots Cytokinin suppression was less pronounced in Pro transformants Exposure to heat stress (40 C for 2 h) at the end of 10-d drought period strongly enhanced the severity of the water stress as indicated by a drop in leaf water potential The activity of cytokinin oxidase/dehydrogenase was strongly stimulated in upper leaves and roots of stressed plants coinciding with strong down-regulation of bioactive cytokinins in whole plants Combined heat and drought stress resulted in a minor decrease in abscisic acid but only in non-wilty upper leaves Both stresses as well as their combination were associated with elevation of free auxin indolylacetic acid in lower leaves and/or in roots Auxin increase was dependent on the stress strength After rehydration a marked elevation of bioactive cytokinins in leaves was observed A greater increase in cytokinin content in Pro transformants indicated a mild elevation of their stress tolerance (C) 2010 Elsevier GmbH All rights reserved