橡胶树暹罗炭疽菌Zn2Cys6型转录因子CsGcc1的生物学功能

Biological functions of the Zn2Cys6 transcription factor CsGcc1 in Colletotrichum siamense

摘要:

【背景】暹罗炭疽菌（Colletotrichum siamense）是一种重要的病原真菌，可以引起炭疽病，给全球橡胶产业带来巨大的经济损失。Zn₂Cys₆型转录因子是真菌特有的锌指类转录因子，通常参与调控真菌的生长发育过程。【目的】在暹罗炭疽菌中鉴定了一个与稻瘟病菌Gcc1同源的Zn₂Cys₆型转录因子CsGcc1，并研究其功能。【方法】根据同源重组原理构建CsGCC1的基因敲除突变体，并通过营养生长、H₂O₂敏感性、分生孢子产生及萌发、玻璃纸试验和致病性分析，明确CsGcc1的功能。【结果】CsGcc1编码一个含有646个氨基酸的蛋白，而且含有一个GAL4结构域。CsGCC1基因在培养36 h的菌丝及分生孢子中具有较高的表达量。CsGCC1基因敲除突变株营养生长速率降低且对H₂O₂更加敏感。相较于野生型菌株，突变株的分生孢子产量、萌发率及附着胞形成率均降低。此外，CsGCC1的敲除可以明显降低分生孢子的穿透能力，突变株对橡胶叶片的致病力减弱。【结论】Zn₂Cys₆型转录因子CsGcc1参与调控暹罗炭疽菌的营养生长、氧化应激、分生孢子发育及致病性等过程。

Abstract:

[Background] Colletotrichum siamense (C. siamense) is a major fungal pathogen causing rubber anthracnose, which has led to substantial economic loss to the world rubber industry. The fungi-specific Zn₂Cys₆ transcription factor regulates the growth and development of fungi.[Objective] A Zn₂Cys₆ transcription factor CsGcc1 was identified from C. siamense, which is homologous to Gcc1 in Magnaporthe oryzae, and its functions were studied.[Methods] The CsGCC1-knockout mutant was developed by homologous recombination, and the functions of CsGcc1 were clarified based on the vegetative growth, H₂O₂ sensitivity, conidial production and germination, cellophane assay and pathogenicity analysis. [Results] CsGcc1 encoded a protein of 646 amino acids and the protein had a GAL4 domain. CsGCC1 was highly expressed in the mycelia and conidia after 36 h culture. The CsGCC1-knockout mutant had slow vegetative growth and low tolerance to H₂O₂. The conidium yield, conidium germination rate, and appressorium formation rate of the mutant were lower than those of the wild type. Cellophane assay showed that deletion of CsGcc1 could weaken the penetration ability of conidia. The virulence of the mutant to rubber leaves was attenuated. [Conclusion] The Zn₂Cys₆ transcription factor CsGcc1 is involved in regulating vegetative growth, oxidative stress, conidium development, and pathogenicity inC. siamense.