过表达草菇Vvmapk对球孢白僵菌生长、抗逆和毒力的影响

Overexpression of Vvmapk affects growth, stress responses, and virulence of Beauveria bassiana

摘要:

【背景】促分裂素原活化蛋白激酶(mitogen-activated protein kinase,MAPK)是真核生物的重要信号分子，介导细胞增殖、分化、细胞凋亡和对外界的应激反应。【目的】研究草菇(Volvariella volvacea)Vvmapk基因功能并进行开发应用。【方法】在Vvpgd强启动子驱动下在球孢白僵菌(Beauveria bassiana)中过表达Vvmapk基因，检测过表达菌株在生长发育、逆境胁迫和毒力方面的变化。【结果】过表达Vvmapk基因的球孢白僵菌生长速度较野生型并未改变，但色素积累和分生孢子的产量显著增加；在热、盐和紫外胁迫下，分生孢子的萌发率显著升高；对大蜡螟(Galleria mellonella)的杀虫能力增强，但对腐皮镰刀菌(Fusarium solani)和尖孢镰刀菌(Fusarium oxysporum)的抑菌效果却减弱。进一步研究发现：过表达菌株中与分生孢子发育相关的BbbrlA、BbabaA和BbwetA基因表达上调。【结论】草菇VvMAPK正调控球孢白僵菌色素生成、分生孢子产量及对胁迫环境的抗性。本研究为草菇的基因功能研究和应用奠定了理论基础。

关键词:球孢白僵菌;草菇;VvMAPK;抗逆性;生长;毒力

Abstract:

[Background] Mitogen-activated protein kinase (MAPK) plays pivotal roles in cell proliferation, differentiation, apoptosis, and stress responses in eukaryotes. [Objective] To identify the roles of Vvmapk in Volvariella volvacea for applications. [Methods] Vvmapk was overexpressed under the control of Vvpgd promoter in Beauveria bassiana, and the roles of Vvmapk in the growth, development, stress responses, and virulence were examined. Compared with the wild type, the overexpression of Vvmapk in B. bassiana increased the pigment level and conidial yield but did not affect the growth. The strains overexpressing this gene displayed higher conidial germination rates under heat shock, salt, and UV-irradiation stress conditions than the control. Furthermore, Vvmapk overexpression endowed the fungi with stronger virulence against Galleria mellonella but weaker antagonistic effects against Fusarium solani and Fusarium oxysporum than the wild type. The relative transcription levels of BbBrlA, BbabaA, and BbwetA associated with the conidial development were significantly up-regulated in the recombinant strain. [Conclusion] VvMAPK positively regulated the conidial development, pigmentation level, and virulence of B. bassiana. The findings laid a theoretical foundation for the functional identification and applications of V. volvacea genes.

Key words:Beauveria bassiana;Volvariella volvacea;VvMAPK;stress responses;growth;virulence