Genome-wide identification and analyses of the AHL gene family in banana (Musa acuminata) and the functional analysis of MaAHL43 in fruit ripening

Banana (Musa acuminata) is one of the most important and popular fruit crops worldwide. The AT-hook motif nuclear localized (AHL) is a conserved transcription factor family involved in the regulation of plant growth and development and stress response. However, the information of MaAHL genes remain largely elusive. In this study, a total of 48 MaAHL genes were identified based on Masu acuminata genome, which were distributed unevenly across 11 chromosomes. Phylogenetic analysis showed that the MaAHL proteins could be divided into two clades of A and B and subdivided into three types. The cis-regulatory elements in the promoter regions of MaAHL genes were mainly involved in diverse functions including plant growth and development, phytohormones responses, and stress response process. Expression profile analysis showed that MaAHL genes responded to osmotic stress and Fusarium oxysporum infection. In addition, the expression of clade-A MaAHL genes were generally downregulated while clade-B MaAHL genes were up-regulated during fruit ripening in banana. RT-qPCR showed that the expression of MaAHL43 gene was significantly up-regulated in middle and late stages of fruit ripening. MaAHL43 is located in nuclear and has no transactivation activity in yeast. Overexpression of MaAHL43 gene could promote banana fruit ripening, indicating MaAHL43 might a regulator of fruit ripening in banana. Taken together, this study would provide valuable information for further studies on the functions of MaAHL genes, and providing a new target for further research on the regulation network of banana fruit ripening.