草菇VvLaeA调控球孢白僵菌的生长发育

Effect of VvLaeA on the growth and development of Beauveria bassiana

摘要:

食用真菌草菇[Volvariella volvacea（Bull.ex.Fr.） Sing.]VvLaeA在调控真菌发育方面的功能并不清楚。本研究在对草菇VvLaeA进行生物信息学分析基础上，通过聚合酶链式反应（polymerase chain reaction，PCR）的方法将超量表达启动子Vvgpd和草菇VvlaeA基因的开放阅读框（open reading frame，ORF）进行融合，并将融合片段克隆入pK2（bar）载体。采用农杆菌介导的转化方法将重组载体pK2（bar）-OEVvlaeA转入球孢白僵菌中进行表达，测定转化子的菌株发育情况。结果表明，草菇VvLaeA与其他真菌的蛋白同源性较低；和野生型相比，转化菌株的菌落直径显著增大，色素减少，分生孢子产量和萌发率均显著下降，对胁迫反应的敏感性增强。进一步研究发现，转化菌株分生孢子的细胞壁结构成分发生改变，和分生孢子发育相关基因的表达被显著下调。提示草菇VvLaeA能提高球孢白僵菌菌株的生长速率，而负调控色素沉积和分生孢子发育，这为草菇基因功能鉴定提供了启示。

Abstract:

It is unclear how VvLaeA functions in regulating the growth and development of Volvariella volvacea (Bull. ex. Fr.) Sing.. Firstly, bioinformatics analysis of VvLaeA was carried out in this study. Subsequently, the Vvgpd promoter and the open reading frame (ORF) fragment of VvlaeA were amplified and fused by polymerase chain reaction (PCR). The fusion fragment was cloned into the pK2 (bar) plasmid. The recombinant construct pK2(bar)-OEVvlaeA was transfected into Beauveria bassiana by Agrobacterium tumefaciens-mediated transformation. Finally, the growth and development of the transformants were examined. The results showed that VvLaeA shared a low homology with similar proteins in other fungi. Compared with the wild type, the colony diameter of the transformant was significantly increased. However, the pigment deposition, conidial yields and germination rates were significantly decreased. The overexpression strains were more sensitive to stresses than that of the wild type. Further studies showed the conidial cell wall properties of the transformants were altered, and the expressions of genes related to the conidial development were significantly down-regulated. Collectively, VvLaeA increased the growth rate of B. bassiana strains and negatively regulated the pigmentation and conidial development, which shed a light for the functional identification of straw mushroom genes.