[Genome-wide identification and effect of MdPEPC family genes during axillary bud outgrowth in apple (Malus domestica Borkh.)].

The PEPC family proteins are ubiquitous in various plants and play an important role in the process of photosynthetic carbon assimilation and have many non-photosynthetic biological functions. However, PEPC genes have not been reported in apple. In this study, the members of apple MdPEPC family were identified based on the new apple genome data by bioinformatics analysis, and their expression patterns in different tissues and the apple axillary bud transcriptome treated by decapitation and TDZ (cytokinin) were analyzed in order to explore the role of MdPEPC genes in apple axillary bud outgrowth. The results showed that 6 MdPEPC family members were identified in apple, which distributed on 6 different chromosomes, and had similar physicochemical characteristics. Phylogenetic tree and sequence alignment analysis showed that the MdPEPC could be divided into two subgroups (Group Ⅰ and Group Ⅱ), in which four members in MdPEPC family were clustered into Group Ⅰ, belonging to plant-type PEPCs. However, MdPEPC4 and MdPEPC5 were clustered into Group Ⅱ with AtPPC4, belonging to bacterial-type PEPCs. There were 7 pairs of fragments repeats among MdPEPC members, but no tandem repeats existed. The promoter cis-acting element analysis showed that MdPEPC genes were not only affected by light and stress, but also regulated by multiple hormones. The expression profiles showed that all MdPEPCs except MdPEPC4 and MdPEPC5 were expressed in different apple tissues. Transcriptome data analysis showed that the expression levels of MdPEPC1 and MdPEPC3 were up-regulated after decapitation and TDZ treatment, whereas MdPEPC2 was significantly down-regulated at 48 h after treatments. In conclusion, MdPEPC1, MdPEPC2 and MdPEPC3 were selected as the candidate genes involved in axillary bud outgrowth regulation for further study.