关键词: 香蕉, 泛素结合酶, 基因, 克隆, 表达分析, 实时定量PCR, 果实成熟

Abstract: A UCE gene, encoding ubiquitin conjugating enzyme was isolated from banana fruit（Musa acuminate L. AAA group‘Brazilian’）and designated MaUCE1. The full length of MaUCE1 cDNA is 890 bp encoding 152 amino acids that shared high identities with the UCE from Nicotiana tabacum, Triticum aestivum, Solanum tuberosum, Arabidopsis thaliana（95.39%, 95.39%, 92.11% and 90.79%）. Amino acid alignment indicated MaUCE1 exists an enzyme activity site of E2 and a conserved cysteine, which is considered to catalyze formation of thioester bond. RT-PCR analysis showed that MaUCE1 is ubiquitously expressed in roots, stems, leaves, flowers and fruits, but the expression level is higher in fruit and flower than those of other organs. During the process of banana fruit postharvest ripening, the mRNA accumulation of MaUCE1 increased in evening of fruit ripening, which is in line with the change of starch phosphorylase activity but negative correlated with change of starch content in this period, suggesting thatMaUCE1 might involve in the catabolism during the process of banana ripening，rather than trigger the fruit ripening.

Key words: banana, ubiquitin conjugating enzyme, gene, cloning, expression analysis, real-time quantitative PCR, ripening