禾谷炭疽菌C2H2型转录因子CgrFlbC的生物学功能

Biological functions of a C2H2-type transcription factor CgrFlbC in Colletotrichum graminicola

摘要:

【背景】 禾谷炭疽菌(Colletotrichum graminicola)是一种既能够在寄主活体细胞内汲取养分，也能通过破坏寄主细胞获得养分的病原真菌。其主要寄生于禾本科植物，可以对这些植物进行侵染从而引起炭疽病。C2H2型转录因子在真菌生长发育过程中起着关键作用。【目的】 鉴定禾谷炭疽菌中一个C2H2型转录因子CgrFlbC，阐明其在该菌中的生物学功能，为进一步解析FlbC在禾谷炭疽菌中的侵染机制提供理论支撑。【方法】 采用同源重组技术分别获得禾谷炭疽菌CgrflbC基因敲除突变株及其互补菌株，对其多种表型特征进行系统分析，包括：不同营养条件下菌丝的生长、非生物胁迫因子响应、产孢及分生孢子发育情况、毒力分析等。【结果】 CgrflbC编码的蛋白质由399个氨基酸组成，含有2个C2H2的锌指结构域。相较于野生型菌株，敲除突变株ΔCgrflbC生长速度减慢，对十二烷基硫酸钠(sodium dodecyl sulfate, SDS)和H₂O₂更敏感，卵圆形孢子产量增加，萌发率降低，镰刀形孢子产量降低，不能形成附着枝。【结论】 CgrFlbC在禾谷炭疽菌中参与调控菌丝生长、细胞壁完整性、氧化应激响应、产孢及孢子萌发以及附着枝的形成，为深入解析禾谷炭疽菌侵染机制奠定了理论基础。

Abstract:

[Background] Colletotrichum graminicola is a pathogenic fungus that can absorb nutrients from host’s living cells or by destroying host’s cells. It mainly parasitizes on gramineae plants and can infect these plants, causing anthracnose. [Objective] To identify a C2H2-type transcription factor CgrFlbC and elucidate its biological functions in C. graminicola, thus laying a theoretical foundation for further understanding the infection mechanism of FlbC in this pathogen. [Methods] Homologous recombination was employed to construct the CgrflbC-deleted strain and complementation strain. The phenotypes of the strains were analyzed, including hyphal development, the integrity of the cell wall, the response to the oxidation stress, the generation of conidial and germination, and the formation of attached branches. [Results] CgrflbC encoded a protein composed of 399 amino acid residues with two C2H2 zinc finger domains. Compared with the wild-type strain, ΔCgrflbC exhibited slow growth and increased sensitivity to sodium dodecyl sulfate (SDS) and H₂O₂. In addition, ΔCgrflbC displayed increased oval conidial production, decreased germination rate and falcate conidial production, and inability of forming hyphopodia. [Conclusion] CgrFlbC is involved in regulating the vegetative growth, cell wall integrity, oxidative stress response, conidial production, germination, and hyphopodium formation of C. graminicola. The findings lay a theoretical foundation for in-depth research on the infection mechanism of C. graminicola.