Tu Jiangying, Qin Li, Karunakaran Chithra, Wei Yangdou, Peng Gary
Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada.
Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada.
Front Plant Sci. 2024 Jul 23;15:1401265. doi: 10.3389/fpls.2024.1401265. eCollection 2024.
Clubroot, caused by , is a significant disease affecting brassica crops worldwide and poses a threat to canola () production in western Canada. Management of this disease heavily relies on the use of resistant cultivars, but resistance erosion is a serious concern due to the highly diverse pathogen populations. Understanding resistance mechanisms may aid in better deployment/rotation of clubroot resistance (CR) genes and improve resistance resilience. In this study, we conducted a comparative analysis using resistant canola varieties carrying either a single () or double CR genes (+ ) to decipher the resistance modes associated with these genes. Cell wall (CW) biopolymeric compounds in different root layers were mapped and quantified using Fourier-transform mid-infrared microspectroscopy for changes in CW elements associated with clubroot resistance. Transmission electron and confocal microscopy were used to assess root infection details and relative transcript abundance was analyzed to determine the activation of the lignin-related pathway in relation to resistance. Neither resistant variety affected the primary infection of root hairs/epidermal cells compared to the susceptible "Westar", but both exhibited strong inhibition of cortical infection, effectively 'trapping' the pathogen in the exodermis. The most prominent change observed was increased lignin accumulation associated with resistance. In Westar, the pathogen was able to degrade CW lignin, facilitating access to the root cortex by secondary plasmodia of . . In contrast, resistant varieties showed clear lignin accumulation around the penetration site on the exodermis, accompanied by elevated expression of genes involved in the phenylpropanoid pathway. These results suggest that induced lignin accumulation plays a role in clubroot resistance mediated by the CR genes and in canola, providing cellular and structural evidence that supports the data from earlier transcriptomic studies.
根肿病由[病原体名称未给出]引起，是一种影响全球芸苔属作物的重要病害，对加拿大西部的油菜籽（[油菜品种未给出]）生产构成威胁。这种病害的管理严重依赖于抗性品种的使用，但由于病原菌群体高度多样，抗性丧失是一个严重问题。了解抗性机制可能有助于更好地部署/轮作根肿病抗性（CR）基因，并提高抗性恢复力。在本研究中，我们使用携带单个（[单个CR基因名称未给出]）或双CR基因（[双CR基因名称未给出]+[另一双CR基因名称未给出]）的抗性油菜品种进行了比较分析，以破译与这些基因相关的抗性模式。使用傅里叶变换中红外显微光谱法对不同根层中的细胞壁（CW）生物聚合物化合物进行映射和定量，以检测与根肿病抗性相关的CW元素变化。使用透射电子显微镜和共聚焦显微镜评估根部感染细节，并分析相对转录本丰度，以确定与抗性相关的木质素相关途径的激活情况。与感病品种“Westar”相比，两个抗性品种均未影响根毛/表皮细胞的初次感染，但两者均表现出对皮层感染的强烈抑制，有效地将病原体“困”在外皮层中。观察到的最显著变化是与抗性相关的木质素积累增加。在Westar中，病原菌能够降解CW木质素，便于[病原菌名称未给出]的次生原质团进入根皮层。相比之下，抗性品种在外皮层穿透部位周围显示出明显的木质素积累，同时苯丙烷途径相关基因的表达升高。这些结果表明，诱导的木质素积累在油菜中由CR基因[单个CR基因名称未给出]和[双CR基因名称未给出]介导的根肿病抗性中起作用，提供了细胞和结构证据，支持了早期转录组学研究的数据。
