Small GTPases RasA and RasB regulate development, patulin production, and virulence of Penicillium expansum

Ras GTPases belong to one of the small G proteins, which regulate morphology and growth of filamentous fungi. However, whether Ras GTPases are involved in the biological process of Penicillium expansum remains unclear. In this study, RasA and RasB gene knockout mutants of P. expansum were constructed. Delta PeRasA and Delta PeRasB showed defective growth, insufficient spore development and malformed mycelium. Loss of PeRasA and PeRasB resulted in a markedly reduction of patulin content and a down-regulation genes expression involved in patulin biosynthesis. Deletion of PeRasA and PeRasB significantly down-regulated the expression of MAPK and cAMP signal regulators. Additionally, Delta PeRasA and Delta PeRasB exhibited attenuated virulence on apple and pear fruit and lower gene expression of cell wall degrading enzymes. In summary, PeRasA and PeRasB were involved in the development, patulin synthesis and virulence of P. expansum by controlling MAPK and cAMP signaling pathways.

Automated summary

RasA and RasB genes were knocked out in P. expansum, resulting in impaired growth, incomplete spore development, and malformed mycelium. Deletion of PeRasA and PeRasB also led to a significant reduction in patulin content and down-regulation of genes involved in patulin biosynthesis. Furthermore, Delta PeRasA and Delta PeRasB exhibited attenuated virulence on apple and pear fruit and lower gene expression of cell wall degrading enzymes. In conclusion, PeRasA and PeRasB control the MAPK and cAMP signaling pathways to regulate the development, patulin synthesis, and virulence of P. expansum.