RhoGAP蛋白CgrRga1参与调控禾谷炭疽菌渗透胁迫响应及分生孢子形态和产量

The RhoGAP protein CgrRga1 is involved in regulating osmotic stress responses and conidial morphology and production in Colletotrichum graminicola

摘要:

背景 禾谷炭疽菌(Colletotrichum graminicola)是一种导致玉米作物患玉米炭疽病(maize anthracnose)的真菌病害。Rho GTPase activating protein (RhoGAP)是调控Rho GTPase家族蛋白活性的一类关键蛋白，通过催化Rho GTPase家族蛋白从GTP激活态转化为GDP失活态，进而调控多种细胞生物学过程，包括细胞骨架重建，基因表达及代谢调控等。目的 从禾谷炭疽菌中鉴定RhoGAP蛋白CgrRga1，通过基因敲除分析该蛋白的生物学功能。方法 通过同源重组的方法获得Cgrrga1基因的敲除突变体，对敲除突变体进行系统性的表型特征分析，研究该基因在生长、胁迫耐受、无性发育及致病性等方面的生物学功能。结果 CgrRga1蛋白含有2个LIM结构域和1个RhoGAP结构域。相较于野生型菌株，敲除突变体ΔCgrrga1对NaCl和KCl更加敏感，部分卵圆形孢子体积增大，镰刀形孢子形态更加细长，并且镰刀形孢子产量下降90%，致病力未受到影响。结论 RhoGAP蛋白CgrRga1参与调控禾谷炭疽菌的渗透胁迫响应，分生孢子形态和产量，不参与调控致病性。相关研究结果可为进一步研究CgrRga1的调控机制，以及深入解析该病菌分生孢子发生的调控机理奠定重要基础。

Abstract:

Background Colletotrichum graminicola is a fungal pathogen that causes maize anthracnose in corn crops. Rho GTPase activating protein (RhoGAP) is key regulator that control the activity of the Rho GTPase family. They catalyze the transition of Rho GTPase family proteins from the GTP-activated state to the GDP-inactivated state, thereby regulating various cellular biological processes, including cytoskeletal reorganization, gene expression, and metabolic regulation.Objective The objective of this study is to identify a RhoGAP protein CgrRga1 from C. graminicola and analyze its biological functions through gene knockout.Methods The knockout mutant of the Cgrrga1 gene was obtained via homologous recombination. A systematic phenotypic characterization of the knockout mutant was conducted to investigate the biological functions of this gene in growth, stress tolerance, asexual development, and pathogenicity.Results CgrRga1 was a RhoGAP protein containing two LIM domains and one RhoGAP domain. The knockout mutant ΔCgrrga1 was more sensitive to NaCl and KCl than the wild-type strain. Some oval conidia of the mutant became enlarged, and falcate conidia became more slender. Moreover, the production of falcate conidia decreased by 90%. The pathogenicity of the mutant remained unaffected.Conclusion The RhoGAP protein CgrRga1 is involved in regulating the osmotic stress responses and conidial morphology and production but does not participate in regulating the pathogenicity of C. graminicola. These findings lay an important foundation for further deciphering the regulatory mechanisms of CgrRga1 and elucidating the regulatory mechanisms of conidiation in C. graminicola.