Expression analysis of NAC genes during the growth and ripening of apples

Abstract

Plant-specific NAC transcription factors (TFs) play crucial roles in various pathways related to the stress response. However, to date, little information regarding NAC gene regulation during fruit ripening is available for the apple (Malus domestica). Here, we report that 13 out of 182 MdNAC genes were differentially expressed during the stages of fruit growth and ripening. Sequence analysis indicates that these 13 MdNAC genes harbour distinct structures and potentially diverse functions. The expression of both MdNAC1a and MdNAC78 was repressed by ethylene and induced by 1- MCP during storage. MdNAC2, MdNAC26, MdNAC41, MdNAC57, MdNAC80, MdNAC91, MdNAC119 and MdNAC141 were up-regulated by ethylene and their transcription mirrored ethylene production rates during storage. MdNAC1, MdNAC16 and MdNAC32 did not respond to 1- MCP exposure. Additionally, the 13 MdNAC genes identified displayed differential tissue-specific expression patterns. These results suggest that NAC TFs play an important role in the regulation of apple development via both ethylene-dependent and -independent mechanisms.