Involvement of LaeA in the regulation of conidia production and stress responses in Penicillium digitatum

Involvement of LaeA in various biological processes of filamentous fungi has been demonstrated. However, its role in Penicillium digitatum, the causal agent of citrus postharvest green mold, remains unclear. In this study, a Delta PdLaeA mutant was constructed using homologous recombination. The production of conidia by the Delta PdLaeA mutant was reduced by half compared with that of the wild-type strain. The sensitivity of the Delta PdLaeA mutant increased under alkaline conditions. The virulence assay revealed that PdLaeA was dispensable for the virulence of P. digitatum. Comparative transcriptome analysis revealed that the function loss of PdLaeA resulted in the reduced expression of several secondary metabolite gene clusters. In addition, expression of several key regulators of conidiation (BrlA, FlbA, FlbC, FlbD, and FluG) was also downregulated in the Delta PdLaeA mutant. In summary, the present work demonstrated that PdLaeA was involved in the regulation of SM biosynthesis, as well as the development and environmental adaptation of P. digitatum.