Abstract:The cloning of an MDH cDNA,designated as MaMDH,was isolated from banana fruit by Suppression Subtractive Hybridization (SSH) and gained by RACE technique.The cDNA was 1 249 bp in length,coding for 332 amino acid residues.Predicted by bioinformatics analysis,its protein molecular weight is 35 448 Da,isoelectric point 6.53.Compared with the known plant malate dehydrogenase (MDH) gene,the homology of amino acid was 92%.By conserved domain analysis,the gene has NAD binding sites,malic acid binding sites,two dimer binding sites.Analyzed by phylogenetic tree,MaMDH are more closely related to corn and wheat.MaMDH stress expression analysis showed that the MaMDH expression of banana seedling dealt with ethephon upregulated,while dealt with salt and Al3+ stress,and banana fusarium oxysporum 4 races firstly upregulated,and then down-regulated.The MaMDH expression by chilling stress down-regulated firstly,and then upregulated.Under the drought stress and wounding stress,the expression of MaMDH did not change significantly.