W ee1 and Cdc 25 control morphogenesis, virulence and multistress tolerance of B eauveria bassiana by balancing cell cycle‐required cyclin‐dependent kinase 1 activity

Summary Modification of cell cycle in entomopathogenic fungi is likely crucial for host infection and environmental adaptation. Here we show that W ee1 and Cdc 25 can balance cell cycle‐required cyclin‐dependent kinase 1 ( Cdk 1) activity in B eauveria bassiana . The Cdk 1 phosporylation signal was strong in Δ cdc 25 but very weak in Δ wee 1 and absent in Δ wee 1 Δ cdc 25 . Consequently, cell cycles, septation patterns and many septation‐dependent gene transcripts of these mutants were reversely changed. Hyphal cells were short in Δ wee 1 , slender in Δ cdc 25 and short and swollen in Δ wee 1 Δ cdc 25 . Conidiation was most defective in Δ wee 1 , followed by Δ cdc 25 . Their conidia and yeast‐like blastospores also altered antagonistically in both size and complexity, accompanied with abnormally branched germlings in Δ wee 1 and Δ wee 1 Δ cdc 25 . Conidial thermotolerance and UV ‐ B resistance decreased much more in Δ wee 1 Δ cdc 25 than in Δ wee 1 but significantly increased in Δ cdc 25 . The double deletion and the point mutation Cdk 1 T14A/P15F for inhibitory phosphorylation caused most defective virulence, followed by wee 1 deletion. All the changes were restored by ectopic gene complementation. Virulence changes in all the mutants and control strains were highly correlated to those in blastospore size or complexity. Taken together, W ee1 and Cdc 25 control cell cycle, morphogenesis, asexual development, stress tolerance and virulence of B . bassiana by balancing the Cdk 1 activity.