Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, 610065, China.
Plant J. 2024 Sep;119(6):2672-2686. doi: 10.1111/tpj.16941. Epub 2024 Jul 23.
The outcome of certain plant-virus interaction is symptom recovery, which is accompanied with the emergence of asymptomatic tissues in which the virus accumulation decreased dramatically. This phenomenon shows the potential to reveal critical molecular factors for controlling viral disease. MicroRNAs act as master regulators in plant growth, development, and immunity. However, the mechanism by which miRNA participates in regulating symptom recovery remains largely unknown. Here, we reported that miR172 was scavenged in the recovered tissue of tobacco mosaic virus (TMV)-infected Nicotiana tabacum plants. Overexpression of miR172 promoted TMV infection, whereas silencing of miR172 inhibited TMV infection. Then, TARGET OF EAT3 (TOE3), an APETALA2 transcription factor, was identified as a downstream target of miR172. Overexpression of NtTOE3 significantly improved plant resistance to TMV infection, while knockout of NtTOE3 facilitated virus infection. Furthermore, transcriptome analysis indicated that TOE3 promoted the expression of defense-related genes, such as KL1 and MLP43. Overexpression of these genes conferred resistance of plant against TMV infection. Importantly, results of dual-luciferase assay, chromatin immunoprecipitation-quantitative PCR, and electrophoretic mobility shift assay proved that TOE3 activated the transcription of KL1 and MLP43 by binding their promoters. Moreover, overexpression of rTOE3 (the miR172-resistant form of TOE3) significantly reduced TMV accumulation compared to the overexpression of TOE3 (the normal form of TOE3) in miR172 overexpressing Nicotiana benthamiana plants. Taken together, our study reveals the pivotal role of miR172/TOE3 module in regulating plant immunity and in the establishment of recovery in virus-infected tobacco plants, elucidating a regulatory mechanism integrating plant growth, development, and immune response.
某些植物-病毒相互作用的结果是症状恢复，伴随着无症状组织的出现，其中病毒积累显著减少。这种现象显示出揭示控制病毒病的关键分子因素的潜力。miRNA 作为植物生长、发育和免疫的主要调节因子。然而，miRNA 参与调节症状恢复的机制在很大程度上仍不清楚。在这里，我们报道了 miR172 在感染烟草花叶病毒（TMV）的烟草植物恢复组织中被清除。miR172 的过表达促进了 TMV 的感染，而 miR172 的沉默抑制了 TMV 的感染。然后，APETALA2 转录因子 TARGET OF EAT3（TOE3）被鉴定为 miR172 的下游靶标。NtTOE3 的过表达显著提高了植物对 TMV 感染的抗性，而 NtTOE3 的敲除促进了病毒感染。此外，转录组分析表明，TOE3 促进了防御相关基因，如 KL1 和 MLP43 的表达。这些基因的过表达赋予了植物对 TMV 感染的抗性。重要的是，双荧光素酶报告基因实验、染色质免疫沉淀定量 PCR 和电泳迁移率变动分析证实，TOE3 通过结合其启动子激活 KL1 和 MLP43 的转录。此外，与 TOE3（正常形式）的过表达相比，rTOE3（miR172 抗性形式）的过表达在 miR172 过表达的拟南芥植物中显著降低了 TMV 的积累。总之，我们的研究揭示了 miR172/TOE3 模块在调节植物免疫和建立病毒感染烟草植物恢复中的关键作用，阐明了一种整合植物生长、发育和免疫反应的调节机制。
