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

水果和蔬菜中乙烯生物合成的基因表达和内部反馈调节

基本信息

批准号：
08456020
负责人：
INABA Akitsugu
金额：
$ 4.93万
依托单位：
OKAYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

. Expression and internal feedback regulation of the genes related to ethylene biosynthesis during development and ripening in several fruits were investigated.In tomato fruit, the preclimacteric system 1 ethylene was possibly mediated via constitutively expressed LE-ACS1A and LE-ACS3 and negatively feedback-regulated LE-ACS6 genes with preexisting LE-ACO1 and LE-ACO4 mRNAs, At the onset of the cimacteric stage, it may shift to system 2 ethylene, with a large accumulation of LE-ACS2, LE-ACS4, LE-ACO1, and LE-ACO4 mRNAs as a result of a positive feedback regulation. This transition from system 1 to system 2 ethylene production might be related to the accumulated level of NR mRNA.Five cDNA fragments encoding ACC synthase or ACC oxidase were cloned from cucumber fruit, a nonclimacteric type. Nevertheless., these were highly homologous in nucleotide sequences to the corresponding genes in melon fruit, a climacteric type, CS-ACS1 gene was not expressed in the ripening cucumber fruit. CS-ACS1 was a wound-inducible gene and CS.ACS3 was an auxin-inducible one. In melon fruit, the difference in the ethylene-forming capability among cultivars resulted from the expression of CMe-ACS1 mRNA during natural fruit ripening and in response to exogenous ethylene.MA-ACS1 was the gene in banana fruit related to the ripening process and was inducible by exogenous ethylene. At the onset of cimacteric, 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 AGO 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 AGO oxidase was, at least in part, due to reduced contents of ascorbate and ferrous, cofactors of the enzyme, during ripening.

.对番茄果实发育成熟过程中乙烯生物合成相关基因的表达和内反馈调控进行了研究，结果表明：番茄果实中乙烯生物合成相关基因LE-ACS 1A和LE-ACS 3组成型表达，LE-ACS 6基因与LE-ACO 1和LE-ACO 4基因负反馈调控，在果实发育成熟过程中，它可能转移到系统2乙烯，由于正反馈调节，LE-ACS 2、LE-ACS 4、LE-ACO 1和LE-ACO 4 mRNA大量积累。从非跃变型黄瓜果实中克隆了5个编码ACC合成酶或ACC氧化酶的cDNA片段。尽管如此，这些基因与跃变型甜瓜果实中相应基因的核苷酸序列高度同源，CS-ACS 1基因在成熟黄瓜果实中不表达。CS-ACS 1是一个创伤诱导基因，CS.ACS3是一个生长素诱导基因。甜瓜果实中乙烯形成能力的品种间差异主要是由CMe-ACS 1 mRNA在果实自然成熟过程中的表达和对外源乙烯的反应引起的，而MA-ACS 1是香蕉果实中与成熟过程相关的基因，受外源乙烯诱导。在环动素期开始时，乙烯产生量急剧增加，并伴随着MA-ACS 1 mRNA积累的增加而出现一个尖锐的峰值，然后迅速下降。乙烯产生的尖峰伴随着体内AGO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。AGO氧化酶的酶活性和基因表达之间的这种差异是，至少部分地，由于抗坏血酸和亚铁，酶的辅因子，在成熟过程中的含量减少。