The Tudor Domain-Containing Protein Bbtdp1 Contributes To Fungal Cell Development, The Cell Cycle, Virulence, And Transcriptional Regulation In The Insect Pathogenic Fungus Beauveria Bassiana

Beauveria bassiana is an insect pathogenic fungus that serves as a model system for exploring the mechanisms of fungal development and host-pathogen interactions. Clinical and experimental studies have indicated that SND1 is closely correlated with the progression and invasiveness of common cancers as a potential oncogene, but this gene has rarely been studied in fungi. Here, we characterized the contributions of an SND1 ortholog (Tdp1) by constructing a BbTdp1 deletion strain and a complemented strain of B. bassiana. Compared with the wild-type (WT) strain, the DBbTdp1 mutant lost conidiation capacity (similar to 87.7%) and blastospore (similar to 96.3%) yields, increased sensitivity to chemical stress (4.4 to 54.3%) and heat shock (similar to 44.2%), and decreased virulence following topical application (similar to 24.7%) and hemocoel injection (similar to 40.0%). Flow cytometry readings showed smaller sizes of both conidia and blastospores for DBbTdp1 mutants. Transcriptomic data revealed 4,094 differentially expressed genes (vertical bar log(2) ratio vertical bar> 2 and a q value of,0.05) between DBbTdp1 mutants and the WT strain, which accounted for 41.6% of the total genes, indicating that extreme fluctuation in the global gene expression pattern had occurred. Moreover, deletion of BbTdp1 led to an abnormal cell cycle with a longer S phase and shorter G(2)/M and G(0)/G(1) phases of blastospores, and enzymelinked immunosorbent assay confirmed that the level of phosphorylated cyclin-dependent kinase 1 (Cdk1) in the Delta BbTdp1 strain was similar to 31.5% lower than in the WT strain. In summary, our study is the first to report that BbTdp1 plays a vital role in regulating conidia and blastospore yields, fungal morphological changes, and pathogenicity in entomopathogenic fungi.IMPORTANCE In this study, we used Beauveria bassiana as a biological model to report the role of BbTdp1 in entomopathogenic fungi. Our findings indicated that BbTdp1 contributed significantly to cell development, the cell cycle, and virulence in B. bassiana. In addition, deletion of BbTdp1 led to drastic fluctuations in the transcriptional profile. BbTdp1 can be developed as a novel target for B. bassiana development and pathogenicity, which also provides a framework for the study of Tdp1 in other fungi.