GENE EXPRESSION AND INTERNAL FEEDBACK REGULATION OF ETHYLENE BIOSYNTHESIS IN RIPENING FRUITS

研究了香蕉和番茄果实成熟过程中乙烯生物合成相关基因的表达和内反馈调控，发现香蕉果实中与成熟过程相关的基因MA-ACS 1可被外源乙烯诱导。进入跃变期后，乙烯释放量急剧增加，并出现一个峰值，同时MA-ACS 1 mRNA的积累也随之增加，随后迅速下降。这种乙烯产生的尖峰伴随着体内ACC氧化酶活性的尖峰。然而，MA-ACO 1转录本的水平仍然很高，从更年期的发病到完全成熟的阶段。ACC氧化酶的酶活性和基因表达之间的这种差异，至少部分，由于减少的抗坏血酸和亚铁，酶的辅因子，在ripening.We研究ACC合成酶的提取方法从香蕉果肉使用聚乙二醇添加缓冲液，然后丙酮洗涤。将乙烯信号转导的下游基因LE-EIL基因导入番茄，获得了转基因番茄植株。

Expression and internal feedback regulation of the genes related to ethylene biosynthesis during ripening in banana and tomato fruits were investigated.MA-ACS1 was the gene in banana fruit related to the ripening process and was inducible by exogenous ethylene. At the onset of climacteric, ethylene production increased greatly with a sharp peak concomitant with an increase in the accumulation of MA-ACS1 mRNA and then decreased rapidly. This sharp peak of ethylene production was accompanying a sharp peak of in vivo ACC oxidase activity. However, the level of MA-ACO1 transcripts remained high from the onset of climacteric to the fully ripe stage. This discrepancy between enzyme activity and gene expression of ACC oxidase was, at leastin part, due to reduced contents of ascorbate and ferrous, cofactors of the enzyme, during ripening.We examined extraction method for ACC synthase from banana pulp using polyethyleneglycol added buffer followed by acetone washing. The method gave a high ACC synthase activity in accordance with ethylene production throughout fruit ripening.A trasgenic tomato plants were obtained in which LE-EIL genes, a most down stream gene in ethylene signalings, were introduced into the plants.