Rhizoctonia solani is a necrotrophic fungal pathogen that causes disease in diverse plant species. In recent years, the genomic and transcriptomic studies have identified several candidate pathogenicity determinants of R. solani; however, most of them remain to be validated. In this study, we report a viral vector-based host-induced gene silencing (HIGS) as well as a dsRNA (double-stranded RNA)-based approach to effectively downregulate genes of R. solani AG1-IA (BRS1 strain) during pathogenesis in tomato. We tested a few of the in-planta upregulated R. solani genes and observed that silencing of one of them, i.e., RS_CRZ1 (a C2H2 type zinc finger transcription factor) significantly compromises the pathogenesis of R. solani in tomato. The RS_CRZ1-silenced plants not only exhibited significant reduction in disease symptoms, but the depth of pathogen colonization was also compromised. Furthermore, we identified the R. solani genes that were coregulated with RS_CRZ1 during the pathogenicity process. The HIGS-mediated silencing of a few of them [CL1756Contig1; subtilisin-like protease and CL1817Contig2; 2OG-Fe(II) oxygenase] compromised the pathogenesis of R. solani in tomato. The ectopic expression of RS_CRZ1 complemented the crz1 mutant of yeast and restored tolerance against various metal ion stress. Overall, our study reveals the importance of RS_CRZ1 in managing the hostile environment encountered during host colonization. Also, it emphasizes the relevance of the HIGS and dsRNA-based gene silencing approach toward functional characterization of pathogenicity determinants of R. solani.

Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

茄枯萎病是一种坏死性真菌病原体，可导致多种植物疾病。近年来，基因组学和转录组学研究已经确定了R. solani的几个候选致病性决定因素。但是，大多数仍然有待验证。在这项研究中，我们报告了一种基于病毒载体的宿主诱导基因沉默（HIGS）以及一种基于dsRNA（双链RNA）的方法，可在发病过程中有效下调R. solani AG1-IA（BRS1株）的基因。在番茄中。我们测试了一些植物内上调的茄红梭菌基因，并观察到其中之一即RS_CRZ1（C2H2型锌指转录因子）的沉默显着影响了其发病机理。番茄中的R. solani。该RS_CRZ1沉默的植物不仅表现在疾病症状显著减少，但病原菌定植深度也遭到了入侵。此外，我们确定了在致病性过程中与RS_CRZ1共同调控的茄红梭菌基因。HIGS介导的其中一些沉默[CL1756Contig1; 枯草杆菌蛋白酶样蛋白酶和CL1817Contig2；2OG-Fe（II）加氧酶]破坏了番茄茄中茄茄的发病机理。RS_CRZ1的异位表达补充了酵母的crz1突变体，并恢复了对各种金属离子胁迫的耐受性。总的来说，我们的研究揭示了RS_CRZ1的重要性管理宿主定殖过程中遇到的不利环境。此外，它强调了基于HIGS和基于dsRNA的基因沉默方法与Solani致病性决定子功能表征的相关性。

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