Abstract: Objective: In order to develop safe, efficient and fungicides with new targets for postharvest disease control of citrus fruit, bioinformatics and expression pattern analysis of the VmaH and PMA genes of Penicillium digitatum were carried out in this study, and we further explored the potentials of the genes as potential antimicrobial targets. Methods: Using various kinds of online software such as Pfam and MEGA 5.0, bioinformatics analysis was performed. Furthermore, the gene expression levels of were analyzed by real-time PCR. Results: It was predicted that there were two highly conserved domains in VmaH, located at the N- and C-terminal ends, respectively. There were three highly conserved domains in PMA, N-terminal, E1-E2 ATPase, and hydrolase domains. Sequences alignment revealed that 79% and 80% identities for VmaH and PMA among different fungi, respectively, which indicates high conservation of VmaH and PMA among different fungi. The obtained cladogram showed that P. digitatum VmaH and PMA were closely related to those of Penicillium and Aspergillus. Compared to PMA, the expression of VmaH was maintained at a higher level throughout the growth of P. digitatum. The expression of PMA was significantly down-regulated during the later stages of P. digitatum growth. Glucose starvation significantly reduced the expression levels of VmaH and PMA, which could be restored by glucose supplementation. In particular, the expression of VmaH was even significantly up-regulated. The expression levels of VmaH and PMA were significantly down-regulated under extreme acid and alkaline conditions. However, the expression of PMA was increased in weakly acidic and alkaline environments. Treatment with either oxidants or reducing agents could significantly reduce the expression levels of VmaH and PMA. Compared with VmaH, the down-regulation of PMA was more significant. The expression of PMA was decreased significantly by treatment with each of the evaluated fungicides, while the responses of VmaH to different fungicide treatments were different. Conclusion: The proteins encoded by VmaH and PMA have the potential to be used as fungicide targets in P. digitatum for further research.

Key words: P. digitatum; VmaH; PMA; gene expression; target