Essential Roles of Two FRQ Proteins (Frq1/2) in Virulence, Infection Cycle and Calcofluor-Specific Signaling of Beauveria bassiana.

Essential Roles of Two FRQ Proteins (Frq1/2) in Virulence, Infection Cycle and Calcofluor-Specific Signaling of Beauveria bassiana. Appl Environ Microbiol. 2021 Jan 04;: Authors: Tong SM, Gao BJ, Peng H, Feng MG Abstract Two FRQ proteins (Frq1/2) distinct in molecular mass and structure coexist in Beauveria bassiana, an asexual insect-pathogenic fungus. Frq1 and Frq2 have been proven to have opposite nuclear rhythms that can persistently activate developmental activator genes, and hence orchestrate nonrhythmic conidiation in vitro under light or in darkness. Here, we report an essentiality of either FRQ, but greater importance of Frq2 than of Frq1, for the fungal virulence and infection cycle. The fungal virulence was attenuated significantly more in the absence of frq2 than of frq1 through either normal cuticle infection or cuticle-bypassing infection by intrahemocoel injection, accompanied by differentially reduced secretion of Pr1 proteases required for the cuticle infection and delayed development of hyphal bodies in vivo, which usually propagate by yeast-like budding in host hemocoel to accelerate insect death from mycosis. Despite insignificant changes in radial growth under normal, oxidative and hyperosmotic culture conditions, conidial yields of the Δfrq1 and Δfrq2 mutants on insect cadavers were sharply reduced, and the reduction increased with shortening daylight length on day 9 or 12 after death, indicating that both Frq...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research