Overexpression of thylakoidal ascorbate peroxidase shows enhanced resistance to chilling stress in tomato
Overexpression of thylakoidal ascorbate peroxidase shows enhanced resistance to chilling stress in tomato
复制标题
类囊体抗坏血酸过氧化物酶的过度表达显示番茄对冷胁迫的抵抗力增强
DOI：
10.1016/j.jplph.2012.02.012
复制
发表时间：
2012-06-15
影响因子：
4.3
通讯作者：
Meng, Qing-Wei
中科院分区：
文献类型：
--
作者：
Duan, Ming;Feng, Hai-Long;Meng, Qing-Wei
光合作用提供了强大的还原能力和产生活性氧（ROS）的高风险，特别是在低温胁迫下。抗坏血酸过氧化物酶（APXs）是将H2 O2还原为水的酶，在植物抗氧化系统中起重要作用。虽然类囊体抗坏血酸过氧化物酶（tAPX）已被认为是细胞内H2 O2水平的关键调节因子，但其在低温胁迫响应中的生理意义仍在讨论中。为了研究tAPX对活性氧清除的贡献，我们分离了番茄类囊体抗坏血酸过氧化物酶基因（LetAPX），并获得了转基因番茄。在拟南芥叶肉原生质体中，LetAPX-GFP融合蛋白被靶向至叶绿体。RNA印迹分析表明，低温、强光、外源水杨酸（SA）和甲基紫精（MV）均能上调LetAPX转录本的表达。过量表达LetAPX的番茄通过保持较高的还原型谷胱甘肽（GSH）含量，叶绿素和APX活性相比，野生型（WT）植物的低温胁迫的耐受性。此外，转基因植株表现出较低的过氧化氢（H2 O2）和离子渗漏水平，较低的丙二醛（MDA）含量，较高的净光合速率（Pn）和较高的PSII最大光化学效率（Fv/Fm）。在低温胁迫下，野生型植株的可氧化性P700比转基因植株的降低更明显。结果表明，tAPX基因的过表达在缓解PSI和PSII光抑制，提高其耐冷性方面发挥了重要作用。(C)2012 Elsevier GmbH. All rights reserved.
Photosynthesis provides a strong reducing power and a high risk for generation of reactive oxygen species (ROS) particularly under chilling stress. Ascorbate peroxidases (APXs) reduce H2O2 to water and play an important role in the antioxidant system of plants. Though thylakoid ascorbate peroxidase (tAPX) has been thought to be key regulator of intracellular levels of H2O2, its physiological significance in the response to chilling stress is still under discussion. To study the contribution of tAPX to the ROS scavenging, a tomato thylakoidal ascorbate peroxidase gene (LetAPX) was isolated and transgenic tomatoes were obtained. The LetAPX-GFP fusion protein was targeted to chloroplast in Arabidopsis mesophyll protoplast. RNA blotting analysis revealed that the LetAPX transcript expression was up-regulated by chilling, high light, exogenous salicylic acid (SA) and methyl viologen (MV). Over expression of LetAPX in tomatoes conferred tolerance to chilling stress by maintaining higher reduced glutathione (GSH) content, chlorophyll and APX activities compared with wild type (WT) plants. Furthermore, transgenic plants showed lower levels of hydrogen peroxide (H2O2) and ion leakage, lower malendialdehyde (MDA) content, higher net photosynthetic rate (Pn) and higher maximal photochemical efficiency of PSII (Fv/Fm). The oxidizable P700 decreased more obviously in WT than that in transgenic plants under chilling stress in low irradiance. The results suggested that over expression of tAPX played a key role both in alleviating photo inhibition of PSI and PSII and enhancing their tolerance to chilling stress. (C) 2012 Elsevier GmbH. All rights reserved.