Xu Xin, Wang Yonglin, Tian Chengming, Liang Yingmei
The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, China.
Museum of Beijing Forestry University, Beijing Forestry University, Beijing, China.
Fungal Genet Biol. 2016 Nov;96:12-24. doi: 10.1016/j.fgb.2016.09.002. Epub 2016 Sep 23.
Rho GTPases regulate morphology and multiple cellular functions such as asexual development, polarity establishment, and differentiation in fungi. To determine the roles of CgRhoB, a Rho GTPase protein, here we characterized CgRhoB in the poplar anthracnose fungus Colletotrichum gloeosporioides. First of all, we determined that conidial germination was inhibited and intracellular cyclic AMP (cAMP) level was increased in the CgRhoB deletion mutants. Loss of CgRhoB resulted in shorter germ tubes and enhanced appressoria formation after germination on the hydrophobic surface. Exogenous addition of cAMP to the wild type generated the similar phenotypes of ΔCgRhoB inoculated in CM liquid. Furthermore, deletion of CgRhoB had discernible effect upon the sensitivity of C. gloeosporioides to cell wall perturbing agents and altered the distribution of chitin on the cell wall. HO sensitivity assay showed the hypersensitive effect on the oxidative stress, and transcriptional analysis revealed that transcription of genes involved in peroxidase activities was altered in the mutants. Finally, virulence assay revealed that CgRhoB was required for pathogenicity. Taken together, our results showed that CgRhoB was associated with appressoria formation and pathogenicity, and affected cAMP level and stress pathways.
Rho GTP酶调节真菌的形态和多种细胞功能，如无性发育、极性建立和分化。为了确定Rho GTP酶蛋白CgRhoB的作用，我们在此对杨树炭疽病菌胶孢炭疽菌中的CgRhoB进行了表征。首先，我们确定在CgRhoB缺失突变体中，分生孢子萌发受到抑制，细胞内环状AMP（cAMP）水平升高。CgRhoB的缺失导致芽管变短，并在疏水表面萌发后增强附着胞的形成。向野生型外源添加cAMP产生了与接种在CM液体中的ΔCgRhoB相似的表型。此外，CgRhoB的缺失对胶孢炭疽菌对细胞壁干扰剂的敏感性有明显影响，并改变了几丁质在细胞壁上的分布。HO敏感性试验显示对氧化应激有超敏反应，转录分析表明突变体中参与过氧化物酶活性的基因转录发生了改变。最后，毒力试验表明CgRhoB是致病性所必需的。综上所述，我们的结果表明CgRhoB与附着胞形成和致病性相关，并影响cAMP水平和应激途径。
