Comparative Transcriptomics and Gene Knockout Reveal Virulence Factors of Arthrinium phaeospermum in Bambusa pervariabilis x Dendrocalamopsis grandis

Arthrinium phaeospermum can cause branch wilting of Bambusa pervariabilis x Dendrocalamopsis grandis, causing great economic losses and ecological damage. A. phaeospermum was sequenced in sterile deionized water (CK), rice tissue (T1) and B. pervariabilis x D. grandis (T2) fluid by RNA-Seq, and the function of Ctf1 beta 1 and Ctf1 beta 2 was verified by gene knockout. There were 424, 471 and 396 differentially expressed genes between the T2 and CK, T2 and T1, and CK and T1 groups, respectively. Thirty DEGs had verified the change in expression by fluorescent quantitative PCR. Twenty-nine DEGs were the same as the expression level in RNA-Seq. In addition, Delta ApCtf1 beta 1 and Delta ApCtf1 beta 2 showed weaker virulence by gene knockout, and the complementary strains Ctf1 beta 1 and Ctf1 beta 2 showed the same virulence as the wild-type strains. Relative growth inhibition of Delta ApCtf1 beta 1 and Delta ApCtf1 beta was significantly decreased by 21.4% and 19.2%, respectively, by adding H2O2 compared to the estimates from the wild-type strain and decreased by 25% and 19.4%, respectively, by adding Congo red. The disease index of B. pervariabilis x D. grandis infected by two mutants was significantly lower than that of wild type. This suggested that Ctf1 beta genes are required for the stress response and virulence of A. phaeospermum.