Whirly1 enhances tolerance to chilling stress in tomato via protection of photosystem II and regulation of starch degradation

First author: Kunyang Zhuang; Affiliations: Shandong Agricultural University (山东农业大学): Tai'an, China

Corresponding author: Qingwei Meng

In plants, the chilling response involves decreased photosynthetic capacity (光合能力) and increased starch accumulation in chloroplasts. However, the mechanisms that modulate these processes remain unclear. We found that the SlWHY1 gene is significantly induced by chilling stress (4°C) in tomato. Three SlWHY1 overexpression (OE) lines grew better than the wild type (WT) under chilling stress; the OE plants retained intact photosynthetic grana lamellae (基粒片层) and showed enhanced hydrolysis (水解) of starch. By contrast, RNAi lines that inhibited SlWHY1 were more affected than the corresponding WT cultivar. Their grana lamellae were damaged and starch content increased. The psbA gene encodes the key photosystem II (PSII) protein D1. We show that SlWHY1 binds to the upstream region (A/GTTACCCT/A) of SlpsbA and enhances the de novo synthesis of D1 in chloroplasts. Additionally, SlWHY1 regulates the expression of the starch‐degrading enzyme α‐amylase (SlAMY3‐L) and the starch synthesis‐r elated enzyme isoamylase gene (SlISA2) in the nucleus, thus modulating the starch content in chloroplasts. We demonstrate that SlWHY1 enhances the resistance of tomato to chilling stress by maintaining the function of PSII and degrading starch. Thus, overexpression of WHY1 may be an effective strategy for enhancing resistance to chilling stress of chilling‐sensitive crops in agricultural production.

在植物中，冷胁迫涉及到叶绿体的光合能力的减弱以及淀粉积累的增加。然而，调控这些进程的分子机制还不清楚。本文中，作者发现番茄中的SlWHY1基因受到4度低温的显著诱导。在冷胁迫条件下，三个SlWHY1过表达株系均要比野生型生长得更好；同时，过表达株系还保留了完整的光合作用基粒片层，并且淀粉的水解增强。相反，抑制SlWHY1基因的RNAi干扰株系要比野生型栽培种更容易受到影响。RNAi干扰株系的基粒片层有所损坏，并且淀粉含量增加。psbA基因编码光合系统PSII的关键蛋白D1。进一步的试验显示SlWHY1结合到SlpsbA基因上游的A/GTTACCCT/A序列，增强叶绿体中D1蛋白的从头合成。另外，SlWHY1调控核中淀粉降解酶α-淀粉酶SlAMY3‐L和淀粉合成相关酶异构淀粉酶SlISA2的表达，进而调整叶绿体中淀粉的含量。本文的研究显示SlWHY1通过维持PSII的功能和淀粉的降解增强番茄对于冷胁迫的抗性。因此，过表达WHY1可能是农业生产中提升低温敏感作物在冷胁迫条件下抗性的有效手段。

通讯：孟庆伟  (http://life.sdau.edu.cn/2013/0516/c2455a27379/page.htm)

个人简介：1978-1985年，山东农业大学，学士、硕士；1995年，山东农业大学，博士；1996-1998年，德国明斯特大学，博士后。

研究方向：1. 植物光合作用及分子调控：以重要农作物小麦、番茄等为材料，克隆与光保护机制和高光效密切相关的重要基因，并分析其功能，为分子育种提供基因资源。2. 植物抗逆境性及分子机制：克隆、鉴定与低温和高温胁迫密切相关的基因，分析其功能。

doi: https://doi.org/10.1111/nph.15532

Journal: New Phytologist

Published online: 15 November, 2018