National Education Ministry, Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, PR China.
Key Laboratory of Applied Genetics of Universities in Fujian Province, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
Plant Cell Environ. 2022 Feb;45(2):459-478. doi: 10.1111/pce.14222. Epub 2021 Nov 22.
Plant diseases generally tend to be more serious under conditions of high temperature and high humidity (HTHH) than under ambient temperature, but plant immunity against pathogen attacks under HTHH remains elusive. Herein, we used pepper as an example to study how Solanaceae cope with Ralstonia solanacearum infection (RSI) under HTHH by performing RNA-seq combined with the reverse genetic method. The result showed that immunities mediated by salicylic acid (SA) and jasmonic acid (JA) in pepper roots were activated by RSI under ambient temperature. However, upon RSI under HTHH, JA signalling was blocked and SA signalling was activated early but its duration was greatly shortened in pepper roots, instead, expression of CaIPT5 and Glutathione S-transferase encoding genes, as well as endogenous content of trans-Zeatin, were enhanced. In addition, by silencing in pepper plants and overexpression in Nicotiana benthamiana, CaIPT5 was found to act positively in the immune response to RSI under HTHH in a way related to CaPRP1 and CaMgst3. Furthermore, the susceptibility of pepper, tomato and tobacco to RSI under HTHH was significantly reduced by exogenously applied tZ, but not by either SA or MeJA. All these data collectively suggest that pepper employs cytokinin-mediated immunity to cope with RSI under HTHH.
高温高湿（HTHH）条件下植物病害通常比常温下更为严重，但植物在 HTHH 条件下对病原体攻击的免疫机制仍难以捉摸。本文以辣椒为例，通过 RNA-seq 结合反向遗传学方法研究茄科植物如何应对 Ralstonia solanacearum 感染（RSI）在 HTHH 下。结果表明，常温下 RSI 激活了辣椒根中的水杨酸（SA）和茉莉酸（JA）介导的免疫。然而，在 HTHH 下的 RSI 中，JA 信号被阻断，SA 信号虽然早期被激活，但持续时间大大缩短，而 CaIPT5 和谷胱甘肽 S-转移酶编码基因的表达以及内源反式玉米素的含量增加。此外，通过在辣椒植株中沉默和在 Nicotiana benthamiana 中过表达，发现 CaIPT5 通过与 CaPRP1 和 CaMgst3 相关的方式在 HTHH 下对 RSI 的免疫反应中起积极作用。此外，外源施用玉米素可显著降低辣椒、番茄和烟草在 HTHH 下对 RSI 的敏感性，但 SA 或 MeJA 则没有这种效果。所有这些数据共同表明，辣椒采用细胞分裂素介导的免疫来应对 HTHH 下的 RSI。
