ABA对甜瓜果实成熟和软化的调节

以甜瓜为材料,分析了果实发育成熟过程中生理生化变化,克隆了ABA生物合成关键酶9-顺环氧类胡萝卜素双加氧酶基因NCED的保守序列并进行表达分析,研究了ABA,NDGA、1-MCP及1-MCP+ABA对果实成熟软化的影响.结果表明:NCED基因在甜瓜果实始熟期大量表达,内源ABA高峰出现在此之后.乙烯释放量,ACC含量和ACO活性在果实成熟初期极低,其各自峰值的出现迟于ABA高峰10 d左右.外源ABA处理显著促进果实成熟和软化,各项成熟指标比对照提前8 d.NDGA处理效果相反;1-MCP和1-MCP+ABA处理与NDGA处理相似,但效果较小.ABA启动了甜瓜果实成熟,它通过诱导乙烯合成相关酶基因的表达而参与了成熟与软化过程,乙烯则主要在成熟后期,尤其是在果实固有风味形成过程中起主导作用.

Effect of abscisic acid(ABA) on melon fruit ripening and softening

The physiological and biochemical changes during melon fruit development and ripening were analyzed,a key enzyme in ABA biosynthesis,9 - cis-epoxycarotenoid dioxygenase gene(NCED),was cloned.Its expression pattern was analyzed.Efffect of ABA,NDGA(nordihydroguaiaretic acid),1-MCP(1-methylcyclopropene) and 1-MCP + ABA on fruit ripening and softening is also investigated.The results showed that NCED gene of melon fruit expressed strongly during early-maturity period.The content of endogenous ABA peaked after NCED gene expression,and then continued to decline.Ethylene production,ACC(1-aminocylopropane-1-carboxylic acid) content and ACO(ACC oxidase) activity in the early fruit maturity is very low,their maximum value is about 10 days late than of endogenous ABA.Exogenous ABA treatment significantly enhanced fruit ripening and softening.Those ripening-relation indexes were eight days earlier than that of the control.On the contrary,the NDGA treatment delayed the ripening-relation index.The effect of 1-MCP and 1-MCP + ABA treatments were similar to that of NDGA,but less effective.ABA initiated the melon fruit ripening,involved in the process of ripening and softening by inducing the expression of genes related to enzymes of ethylene production.Ethylene mainly played a major role in late-ripening period,especially in forming of fruit flavor inherent material.