Genome-wide identification, characterization and expression analysis of NF-Y gene family in relation to fruit ripening in banana

Nuclear factor Y (NF-Y) is a heterotrimeric transcription factor, which plays important roles in plant growth, development and stress responses. Yet little information regarding the role of NF-Y in regulating fruit ripening is available. In this study, a total of 44 NF-Y genes (14 MaNF-YAs, 16 MaNF-YBs, and 14 MaNF-YCs) were isolated and confirmed from the banana genome. Their distribution on chromosomes, gene structures, phylogenetic relationship with other species, cis-acting elements, genome synteny and tissue-specific expression were characterized. Furthermore, it was found that expression of six MaNF-Ys, i.e. MaNF-YA5/B1/B2/C9/C11/C14, were up-regulated as harvested fruit ripened, and their expression were accelerated by ethylene, but delayed by 1-MCP. In contrast, harvested banana fruit ripening was accompanied by down-regulation of MaNF-YA1/A3/A6/ B3/B6/C2/C5. Ethylene accelerated their down-regulation while 1-MCP delayed the process. These results indicated that MaNF-YA5/B1/B2/C9/C11/C14 and MaNF-YA1/A3/A6/B3/B6/C2/C5 were implicated in the regulation of harvested banana fruit ripening, functioning as transcriptional activators and repressors, respectively.