The FRP1 F-box gene has different functions in sexuality, pathogenicity and metabolism in three fungal pathogens

Area of Science:

• Plant Pathology
• Mycology
• Molecular Biology

Background:

• Plant-pathogenic fungi utilize diverse infection strategies, suggesting species-specific protein requirements.
• The F-box protein Frp1 (FRP1) is essential for pathogenicity and nonsugar carbon catabolism in Fusarium oxysporum.
• FRP1 is conserved in filamentous fungi within Sordariomycetes, Leotiomycetes, and Dothideomycetes.

Purpose of the Study:

• To investigate the role of the F-box protein Frp1 in pathogenicity and carbon source utilization in Fusarium graminearum and Botrytis cinerea.
• To determine if FRP1 function is conserved across different fungal species.

Main Methods:

• Generation of FRP1 deletion mutants in Fusarium graminearum (Fg) and Botrytis cinerea (Bc).
• Phenotypic analysis of mutants, including pathogenicity assays on barley and growth assessments on various carbon sources.
• Functional complementation by replacing Fusarium oxysporum FRP1 (FoFRP1) with Botrytis cinerea FRP1 (BcFRP1).

Main Results:

• FgFRP1 deletion impaired barley root infection but not aerial infection; BcFRP1 deletion had no effect on pathogenicity.
• Sexual reproduction was impaired in both Fg and Bc FRP1 deletion mutants.
• Mutants exhibited distinct carbon source utilization phenotypes, with F. oxysporum and B. cinerea mutants showing opposite growth patterns on sugar vs. nonsugar sources.
• Replacing FoFRP1 with BcFRP1 restored pathogenicity in F. oxysporum but altered carbon source utilization, indicating functional divergence.

Conclusions:

• The function of the F-box protein Frp1 is not conserved across different fungal species, despite sequence conservation.
• Differential requirements for pathogenicity and carbon source utilization highlight species-specific roles of Frp1.
• Promoter sequences may contribute to the functional divergence of FRP1 between fungal species.