A Banana Fruit MaJAZ3 Interacts With Transcriptional Factor MaERF10 To Synergistically Regulate MeJA-induced Cold Tolerance

Banana is a kind of typical climacteric fruits, and low temperature storage can effectively delay its ripening and softening, as well as prolong its storage life. However, banana fruit is easily subject to chilling injury, which seriously affects of its commercial quality. Our previous studies found that the application of jasmonic acid(JA) and its derivative Me JA can induce chilling tolerance of banana fruit, while the underlying regulatory mechanisms of this process remain largely unknown. In this work, the mechanism of thesynergism between Ma JAZ and MaERF10 involving in Me JA-induced chilling tolerance of banana fruit was investigated. The main results are as follows:1. Based on the banana genome sequences, eight JAZ genes, designated as Ma JAZ1 to Ma JAZ8, were isolated and characterized from banana fruit. Yeast two-hybrid and bimolecular fluorescence complementation(Bi FC) assays revealed that MaJAZ3 physically interacted with MaERF10. In addition, subcellular localization analysis showed that both MaJAZ3 and MaERF10 proteins localized to the nucleus.2. RT-q PCR analysis reavealed that both MaJAZ3 and MaERF10 were cold-responsive, and their expressions were reduced by exogenous Me JA treatment.3. Electrophoretic mobility shift(EMSA) and dual luciferase reporter(Dual-LUC) assays indicated that MaERF10 was able to bind to and suppress the promoter activities of several JA biosynthetic genes, such as MaLOX7/8, MaAOC3, and MaOPR4. Moreover, the interaction of MaJAZ3 and MaERF10 led to deeper repression of JA biosynthetic genes by MaERF10.Taken together, our findings suggest that banana MaJAZ3 interacts with MaERF10, and they act synergistically to repress the expressions of JA biosynthetic genes, which provides new insights into a transcriptional regulatory network of Me JA-induced chilling tolerance of banana fruit.