| Banana is a large tropical herbaceous fruit tree, which is sensitive to stresses such as low temperature and reduce fruit quality and yield. Studies on mechanisms involved in respose to low temperature is helpful in production and breeding of banana. It has been reported that Ran is involved in responses to stresses in plants and overexpression of Ran enhances the sensitivity to stresses and cold resistance in plants. In this study, Ran family genes in genome of Musa acuminata were analyzed. Meanwhile, wild banana from Sanming, which is resistant to cold stress, is used for isolation and analysis of Ran family genes. Furthermore, the expression of Ran family genes in different tissues and under low temperature stress were analysed. Our main results are as follows:1Genome-wide analysis of the Ran gene family in Musa acuminata9MuRan family genes were identified in banana genome and their chromosome distribution, gene structure, physical and chemical characteristics, function domain and evolutionary relationship were analyzed. The results indicated that MuRan family genes were uevenly distributed in4chromosomes. MuRan proteins showed high homology with Ran proteins from other plant specie and contained characteristic domains of the Ran proteins including GTP hydrolysis domain, RanGAP-binding domain and acidic tail and were relatively closer with AtRan in phylogenetic relationship.2Cloning and bioinformatics analysis of MsRan family genes in wild banana from Sanming12cDNA sequences and15DNA sequences of Ran gene were isolated from Sanming wild banana.(1) Analyses of12cDNA sequences of Ran gene indicated that their ORF sequences were highly homologous. MsRan3A-1a, MsRan3A-6a and MsRan3A-5were transcripts produced by alternative splicing, they existed sequence deletion in coding region and3’UTR respectively. These cDNA encoded6proteins, including MsRan3A, MsRan3B, MsRan3C, MsRan3D, MsRan3A-la and MsRan3A-6a. Analyses of amino acid sequence of these proteins indicated MsRan3A, MsRan3B, MsRan3C and MsRan3D were similar in physicochemical property, subcellular location, phosphorylation sites, secondary structure and three-dimensional structure. However, physicochemical property, subcellular location, secondary structure and three-dimensional structure of MsRan3A-la and MsRan3A-6a appeared significantly different from that of MsRan3A, MsRan3B, MsRan3C and MsRan3D. Sequence alignment and phylogenetic analysis demonstrated that Ran proteins were highly conserved. MsRan3A, MsRan3B, MsRan3C, MsRan3D and MsRan3A-la contain characteristic domains of the Ran proteins including GTP Hydrolysis domain, RanGAP-binding domain and acidic tail, but2G boxes (G4and G5) were absence in MsRan3A-6a.(2) Analyses of15DNA sequences of Ran gene indicated that Ran genes in Sanming wild banana were highly homologous with that in Musa acuminata and contained many polymorphic sites. The large number of Ran family genes implicated that they may play important roles in Sanming wild banana.3Expression analysis of MsRan family genes in wild banana from SanmingAnalyses of tissue specific expression of Ran family genes indicated that MsRan3A-1, MsRan3A-2, MsRan3A-3, MsRan3A-4, MsRan3A-5, MsRan3A-6, MsRan3A-6a, MsRan3B-1, MsRan3B-2, MsRan3C-1and MsRan3D-1were expressed in root, leaf, peduncle, bract, flower, peel and pulp in wild banana from Sanming. MsRan3A-la was expressed in extremely low levels in these tissues and undetectable by qPCR. expression of Ran family genes were analyzed under low temperature stress in wild banana from Sanming. We found that MsRans were involved in responses to low temperature stress and various transcripts respond to low temperature stress in different patterns, our result suggested that MsRan may be involved in cell division. Furthermore, the effects of SA on expression of Ran family genes in wild banana from Sanming were determined, we found that SA significantly enhanced the expression of MsRan genes, which suggested that MsRan genes are involved in SA signal transduction. |
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