Banana MYBs Transcription Factors And MaGBSSⅠ-3 Promoter Interactions Regulation Research

Banana is one of the important economic crops in tropical and subtropical countries,which also is a starch-converting fruit.Therefore,the starch content is an important factor for the yield,quality and flavor in banana fruits.Granule-bound starch synthase(GBSS)is a key enzyme for amylose synthesis.Currently,the research on GBSS focused on its functions,but the transcriptional regulation mechanism of the upstream promoter of GBSS is rarely studied.Our previous studies showed that MaGBSSⅠ-3 play a crucial role in the starch biosynthesis of banana,thus this study focus on the regulation mechanism of MaGBSSⅠ-3 gene.In this study,the yeast one-hybrid technology,EMSA(electrophoretic mobility shift assay),and a transient expression system were used to identify the interact mechanism of the MaGBSSI-3 promoter with candidate transcription factors,the main results were as follows:1.The cis-elements of MaGBSSI-3 gene promoter region,including anaerobic induction,methyl jasmonate,light,gibberellins,MYB and other response elements,were found through the PLANTCARE software.2.47 transcription factors(TF)interacting with the MaGBSSⅠ-3 gene promoter,such as ARFs,b HLHs,C2H2 s and MYBs,were predicted by Plant TF database analysis.3.Three TF families,including MYB,ERF,and HD-ZIP,were identified based on transcriptome data and exhibited higher expression with the fruit developmental processes,and implying these TFs may play a crucial role in banana starch biosynthesis.4.Six MYB genes,including Ma MYB1 a,Ma MYB1 b,Ma MYB4,Ma MYB44,Ma MYB5,and Ma MYB6,were cloned,the c DNA full-length was 681 bp,726 bp,1116 bp,1116 bp,1110 bp,and 1038 bp,respectively,and encoded 226,241,371,371,369,and 345 amino acids,respectivly.QRT-PCR results exhibited that MYB44 is higher expression than that other MYBs members during banana fruit development.5.Yeast one-hybrid results showed that Ma MYB1 a,Ma MYB4,Ma MYB44,Ma MYB5,and Ma MYB6 interact with the MaGBSSⅠ-3 promoter.Among them,the MYB44 can bind of the MaGBSSI-3 gene promoter by EMSA experiments.Transient expression experiments exhibit that the MYB44 can bing the promoter and inhibit the expressionof the MaGBSSI-3 gene.