MaERF9 and MaERF113 transcription factors involve in chilling injury development by regulating membrane lipid metabolism of postharvest banana fruit

Banana is a cold-sensitive fruit, which exhibits vulnerability to chilling injury (CI), causing browning, pitting, even abnormal ripening, resulting in quality deterioration and economic loss. CI development of banana fruit was caused by membrane integrity damage and was related to the enzymatic and genetic manipulation of membrane lipid metabolism pathway. The involvement of Ethylene Response Factor (ERF) transcription factors (TFs) in membrane lipid-mediated CI development of cold-sensitive fruit, such as banana, remains largely unknown. In this study, we found that cold treatment increased CI index, cell membrane permeability and MDA content, decreased hue angle (h°) value. The expressions of membrane lipids metabolism genes, including MaDGK, MaPLA, MaLipase and MaLOX, were upregulated by cold treatment. Also, two banana ERF TFs, designated as MaERF9 and MaERF113, were induced by cold environment and displayed transactivation activities. Additionally, the electrophoretic mobility shift assay (EMSA) and transient expression analysis showed that MaERF9 and MaERF113 directly bound to the GCC-box elements in the promoters of MaDGK, MaPLA, MaLipase and MaLOX, and activated their expressions. These findings imply that MaERF9 and MaERF113 involved in CI development of banana fruit, via affecting membrane lipid metabolism. Collectively, our results provide new insights into the transcriptional regulation network regulating CI development of banana fruit.