The Mechanism Of ERF Transcription Factor And Fatty Acid Desaturase Involved In The Regulation Of ABA-induced Cold Tolerance Of Banana Fruits

Bananas are one of the major fruits exported and north-transported in southern China.If the fruit growing season suffered low temperature or temperature is below 11 ℃during storage or transportation,banana will be prone to chilling injury,seriously affecting the commercial value of the fruit.ERF transcription factors play an important role in plant response to biotic and abiotic stresses.Our previous studies found that exogenous ABA treatment can induce cold tolerance in banana fruits,but the specific regulatory mechanisms are not yet fully understood.In particular,there are few reports on whether ERF and membrane lipid metabolism are involved in ABA-induced banana fruit cold tolerance.For this reason,in this paper,two ERF genes and FADs genes were isolated,and named MaERF111/91 and MaFAD3-1/5/7 respectively.The effect of low temperature and exogenous ABA treatment on the expression of these genes was investigated.The relationship between MaERF111/91 and MaFADs genes was examined to clarify the role of ERF and FADs genes in ABA-induced cold tolerance of banana fruits’ mechanism.The main results obtained are as follows:1.The amino acid sequence and phylogenetic tree analysis indicated that these two genes both contained one AP2 / ERF domain and belonged to the ERF transcription factor;subcellular localization showed that MaERF111/91 was located in the nucleus and was nuclear protein;transcription activity analysis showed that MaERF111 /91 both have transcriptional activation activity and are transcriptional activators.three MaFADs genes were isolated from banana fruit and named MaFAD3-1/5/7.2.The effects of low temperature and exogenous ABA on the expression of MaERF111/91 and MaFADs were studied.Exogenous ABA could alleviate the chilling injury of banana fruits.At the same time,exogenous ABA treatment could significantly enhance the expression of MaERF111/91 and MaFAD3-1/5/7,in addition,saturated fatty acids increase and unsaturated fatty acid content decreases gradually during storage at low temperature,and to a certain extent,exogenous ABA can can delay the rise of saturated fatty acids and inhibit the decline of unsaturated fatty acids.3.MaERF111 can directly bind MaFaD3-1/5/7 promoter and activate its activity.MaERF91 can only directly bind MaFaD3-1 promoter and activate its activity.The results showed that MaERF111/91 regulates the change of unsaturated fatty acids through the combination of MaFADs promoter,and then regulates the response of banana fruits to cold stress and ABA induced cold tolerance.