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Z. Naturforsch. 69c, 300 – 308 (2014)
doi:10.5560/ZNC.2013-0181
Water Stress Enhances Expression of Genes Encoding Plastid Terminal Oxidase and Key Components of Chlororespiration and Alternative Respiration in Soybean Seedlings
Xin Sun1,2,*, Cui-Qin Yang1,3, Tao Wen1, Fu-Chun Zeng1, Qiang Wang1, Wen-Yu Yang2,*, and Hong-Hui Lin3
1 Department of Plant Physiology, College of Agronomy, Sichuan Agricultural University, Chengdu 611130, China. E-mail: sunxin529@hotmail.com
2 Key Laboratory of Crop Eco-physiology and Farming System in Southwest China (Ministry of Agriculture), Sichuan Agricultural University, Chengdu 611130, China. E-mail: wenyu.yang@263.net
3 Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu 610064, China
*Authors for correspondence and reprint requests
Received November 19, 2013 / March 9, 2014 / published online July 9, 2014
Plastid terminal oxidase (PTOX) is a plastid-localized plastoquinone (PQ) oxidase in plants. It functions as the terminal oxidase of chlororespiration, and has the potential ability to regulate the redox state of the PQ pool. Expression of the PTOX gene was up-regulated in soybean seedlings after exposure to water deficit stress for 6 h. Concomitantly expression of the NDH-H gene, encoding a component of the NADPH dehydrogenase (NDH) complex which is a key component of both chlororespiration and NDH-dependent cyclic electron transfer (CET), was also up-regulated. Transcript levels of the proton gradient regulation (PGR5) gene, which encodes an essential component of the PGR5-dependent CET, were not affected by water stress, while the expression of the alternative oxidase (AOX1) gene, which encodes a terminal oxidase of alternative respiration in mitochondria, was also up-regulated under water stress. Therefore, our results indicate that water stress induced the up-regulation of genes encoding key components of chlororespiration and alternative respiration. Transcript levels of the AOX1 gene began to increase in response to water stress before those of PTOX suggesting that alternative respiration may react faster to water stress than chlororespiration.
Key words: Chlororespiration, Plastid Terminal Oxidase (PTOX), Water Stress
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