Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
ICAR - Indian Institute of Rice Research, Hyderabad, India.
Mol Plant Pathol. 2022 Sep;23(9):1303-1319. doi: 10.1111/mpp.13230. Epub 2022 May 19.
Ascorbic acid (AsA) is an important antioxidant in plants and regulates various physiological processes. In this study, we show that exogenous treatments with the oxidized form of AsA, that is, dehydroascorbate (DHA), activates induced systemic resistance in rice against the root-knot nematode Meloidogyne graminicola, and investigate the molecular and biochemical mechanisms underlying this phenotype. Detailed transcriptome analysis on roots of rice plants showed an early and robust transcriptional response on foliar DHA treatment, with induction of several genes related to plant stress responses, immunity, antioxidant activity, and secondary metabolism already at 1 day after treatment. Quantitative and qualitative evaluation of H O levels confirmed the appearance of a reactive oxygen species (ROS) burst on DHA treatment, both at the site of treatment and systemically. Experiments using chemical ROS inhibitors or scavengers confirmed that H O accumulation contributes to DHA-based induced resistance. Furthermore, hormone measurements in DHA-treated plants showed a significant systemic accumulation of the defence hormone salicylic acid (SA). The role of the SA pathway in DHA-based induced resistance was confirmed by nematode infection experiments using an SA-signalling deficient WRKY45-RNAi line and reverse transcription-quantitative PCR on SA marker genes. Our results collectively reveal that DHA activates induced systemic resistance in rice against the root-knot nematode M. graminicola, mediated through the production of ROS and activation of the SA pathway.
抗坏血酸（AsA）是植物中一种重要的抗氧化剂，调节各种生理过程。在本研究中，我们表明，外源性处理 AsA 的氧化形式，即脱氢抗坏血酸（DHA），可激活水稻对根结线虫 Meloidogyne graminicola 的诱导系统抗性，并研究了这种表型的分子和生化机制。对水稻根系的详细转录组分析表明，叶面 DHA 处理后会出现早期且强烈的转录响应，诱导与植物应激反应、免疫、抗氧化活性和次生代谢相关的几个基因的表达，在处理后 1 天即可检测到。H O 水平的定量和定性评估证实了 DHA 处理后会出现活性氧（ROS）爆发，无论是在处理部位还是系统部位。使用化学 ROS 抑制剂或清除剂的实验证实，H O 积累有助于基于 DHA 的诱导抗性。此外，在 DHA 处理的植物中进行激素测量显示，防御激素水杨酸（SA）在系统中大量积累。使用 SA 信号缺陷 WRKY45-RNAi 系进行线虫感染实验和 SA 标记基因的逆转录定量 PCR 证实了 SA 途径在 DHA 诱导的抗性中的作用。我们的研究结果表明，DHA 通过产生 ROS 和激活 SA 途径，激活水稻对根结线虫 M. graminicola 的诱导系统抗性。
