禾谷炭疽菌G蛋白α亚基CgrGa3调控营养生长、胁迫响应、孢子产生和致病性

G protein α subunit CgrGa3 regulates vegetative growth, stress responses, conidial production, and pathogenicity of Colletotrichum graminicola

摘要:

【背景】 禾谷炭疽菌(Colletotrichum graminicola)是危害玉米(Zea mays)等作物的一种重要病原真菌。异源三聚体G蛋白在丝状真菌信号转导中发挥关键作用，其中Gα亚基是G蛋白的主要组成成分。【目的】 鉴定禾谷炭疽菌中的G蛋白III型Gα亚基CgrGa3，探讨其在该菌生长和发育中的功能。【方法】 通过基因敲除构建其敲除突变体，开展多层次的表型分析，包括菌丝生长、应激响应、孢子产生与萌发及致病性等方面的实验。【结果】 CgrGa3编码一个含有355个氨基酸的蛋白，包含一个G_alpha结构域。CgrGa3缺失突变体表现出菌落生长缓慢，对NaCl、KCl和H₂O₂更加敏感，卵圆形和镰刀形孢子的产量和萌发率均显著下降，致病力明显减弱；而互补菌株能够恢复以上表型缺陷。【结论】 CgrGa3在调控禾谷炭疽菌的营养生长、胁迫响应、无性发育和致病过程中发挥了重要作用。

Abstract:

[Background] Colletotrichum graminicola is a pathogenic fungus that poses threats to crops such as Zea mays. Heterotrimeric guanine nucleotide-binding proteins (G proteins) play a crucial role in signal transduction of filamentous fungi, with the G protein α subunit being a major component. [Objective] This study identified the G protein α subunit (group III) CgrGa3 in C. graminicola and investigate its role in the growth and development of this pathogen. [Methods] CgrGa3-deleted mutants were constructed by gene knockout. The phenotypes of the mutants were characterized, including the hyphal growth, stress responses, conidial production, conidial germination, and pathogenicity. [Results] CgrGa3 encoded a protein composed of 355 residues and containing a G_alpha domain. The CgrGa3-deleted mutants exhibited inhibited growth, increased sensitivity to NaCl, KCl and H₂O₂, and reduced production and germination rates of oval and falcate conidia. Additionally, the pathogenicity of the mutants was markedly weakened. The complementation of this gene restored these phenotypic defects. [Conclusion] CgrGa3 plays a critical role in regulating the vegetative growth, stress responses, asexual development, and pathogenicity of C. graminicola.