State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, China.
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, China.
Mol Plant Pathol. 2021 Feb;22(2):243-254. doi: 10.1111/mpp.13023. Epub 2020 Dec 5.
MicroRNAs play important roles in various biological processes by regulating their corresponding target genes. However, the function and regulatory mechanism of fungal microRNA-like RNAs (milRNAs) are still largely unknown. In this study, a milRNA (Vm-milR37) was isolated and identified from Valsa mali, which causes the most serious disease on the trunk of apple trees in China. Based on the results of deep sequencing and quantitative reverse transcription PCR, Vm-milR37 was found to be expressed in the mycelium, while it was not expressed during the V. mali infection process. Overexpression of Vm-milR37 did not affect vegetative growth, but significantly decreased pathogenicity. Based on degradome sequencing, the target of Vm-milR37 was identified as VmGP, a glutathione peroxidase. The expression of Vm-milR37 and VmGP showed a divergent trend in V. mali-apple interaction samples and Vm-milR37 overexpression transformants. The expression of VmGP could be suppressed significantly by Vm-milR37 when coexpressed in tobacco leaves. Deletion of VmGP showed significantly reduced pathogenicity compared with the wild type. VmGP deletion mutants showed more sensitivity to hydrogen peroxide. Apple leaves inoculated with Vm-milR37 overexpression transformants and VmGP deletion mutant displayed increased accumulation of reactive oxygen species compared with the wild type. Thus, Vm-milR37 plays a critical role in pathogenicity by regulating VmGP, which contributes to the oxidative stress response during V. mali infection. These results provide important evidence to define the roles of milRNAs and their corresponding target genes in pathogenicity.
微小 RNA 通过调控其相应的靶基因在各种生物过程中发挥重要作用。然而，真菌微小 RNA 样 RNA（milRNA）的功能和调控机制在很大程度上仍然未知。本研究从引起中国苹果树树干最严重病害的苹果腐烂病菌中分离并鉴定了一个 milRNA（Vm-milR37）。基于深度测序和定量反转录 PCR 的结果，发现 Vm-milR37 在菌丝中表达，而在 V. mali 感染过程中不表达。过表达 Vm-milR37 并不影响营养生长，但显著降低了致病性。基于降解组测序，鉴定出 Vm-milR37 的靶标为 VmGP，一种谷胱甘肽过氧化物酶。在 V. mali-苹果互作样本和 Vm-milR37 过表达转化体中，Vm-milR37 和 VmGP 的表达呈发散趋势。当在烟草叶片中共表达时，Vm-milR37 可以显著抑制 VmGP 的表达。与野生型相比，VmGP 的缺失突变体表现出明显降低的致病性。与野生型相比，VmGP 缺失突变体对过氧化氢表现出更高的敏感性。与野生型相比，接种 Vm-milR37 过表达转化体和 VmGP 缺失突变体的苹果叶片显示出活性氧物质积累的增加。因此，Vm-milR37 通过调控 VmGP 来调节致病性，这有助于 V. mali 感染过程中的氧化应激反应。这些结果为定义 milRNA 及其相应靶基因在致病性中的作用提供了重要证据。
