Improvement of Pythium guiyangense by constructive expression of Pr1 gene

Abstract:

[Objective] To construct a constructive expression vector pCambia-hph-Pr1 containing a Pr1 ORF of Pythium guiyangense for transformation of the fungus to get a genetic recombinant strain with enhanced virulence against mosquito larvae. [Methods] The Pr1 gene expression vector was constructed using a binary vector as basic frame, and Pr1 gene was placed between promoter PgpdA and terminator TtrpC. The recombinant strains were obtained by Agrobacterium-mediated transformation system, with P. guiyangense mycelia as acceptor, using vector pCambia-hph-Pr1 containing hygromycin B resistance gene as marker. The biological characteristics and virulence to Culex larvae of the transformant were observed. [Results] No distinct difference was found between wild-type stain and transformant in terms of growth rate and zoospore yield. A transformed strain of the fungus with significantly improved virulence was achieved. It caused an average larval death rate of 32.9% which was approximately double that of wild-type stain. Besides, the larvae exposed to transformant grew obviously slower. [Conclusion] A genetically stable strain with higher virulence was obtained by constitutive expression of Pr1 protease through Agrobacterium-mediated transformation.

Key words:biocontrol, Constructive expression, virulence against Culex larvae