论文部分内容阅读
柿子通常被归类为呼吸跃变型果实.然而,与典型的跃变型果实不同,它表现出独特的跃变特性,即越早期采下的果实,乙烯产生量越大.为了弄清柿离体幼果的乙烯生成及诱导机制,从果萼中克隆了1个编码ABA生物合成关键酶基因(DK-NCED1)的cDNA片段,并分析其在离体幼果中的表达及其产物ABA对乙烯生成的影响.结果显示,幼果采后置于室温下,萼片首先失水,其DK-NCED1基因于采后第1天开始表达,并伴随着ABA的快速积累,ABA在采后第2天达到峰值,然后下降.果萼中DK-ACS2和DK-ACO1基因从采后第2天开始表达,乙烯随即诱导产生,并于第3天达到峰值.果实中也存在上述变化模式,但各项指标均比果萼晚1d,且果肉硬度从采后第4天急速下降,并于第6天完全软化.外源ABA或NDGA(一种NCED酶抑制剂)对离体幼果DK-NCED1基因的表达无影响,但却促进或抑制了果实中乙烯合成酶基因DK-ACS2及氧化酶基因DK-ACO1的表达及其乙烯的生成,促进或延迟了幼果的软化.结果表明,柿幼果采后,失水胁迫诱导了果萼中DK-NCED1基因的表达,并诱导ABA的快速积累;ABA达到一定值后触发乙烯生物合成酶基因DK-ACS2和氧化酶基因DK-ACO1基因的表达,乙烯随即生成并扩散至果肉,作为二级信号刺激果肉中乙烯的合成,并引发乙烯的跃变,使果实软化.
Persimmon is generally classified as a climacteric fruit, however, unlike typical climacteric fruits, it exhibits a unique jump characteristic, ie, the earlier the fruit is taken, the greater the amount of ethylene produced.In order to understand persimmon A new cDNA encoding the key enzyme gene of ABA biosynthesis (DK-NCED1) was cloned from the calyx and analyzed for its expression in isolated young fruit and its product ABA to ethylene The results showed that semen was first dehydrated after young fruits were harvested at room temperature. The DK-NCED1 gene began to express on the first day post-harvest and was accompanied by the rapid accumulation of ABA. On the second day after harvest, Reached its peak and then decreased.The expression of DK-ACS2 and DK-ACO1 genes in calyxes began at the second day after harvest and ethylene was induced and peaked on the third day.The above pattern of changes also existed in fruits, The indexes were all lower than that of the calyxes for 1 day, and the firmness of fruit declined rapidly from the 4th day after harvest and completely softened on the 6th day. Exogenous ABA or NDGA, an NCED enzyme inhibitor, , But it promoted or inhibited the expression of ethylene synthase gene DK-ACS2 and oxidase DK-ACO 1 expression and ethylene production promoted or delayed the softening of young fruits.The results showed that the dehydration stress induced the expression of DK-NCED1 gene in calyx and induced the rapid accumulation of ABA. After reaching a certain value, ethylene biosynthesis enzyme gene DK-ACS2 and oxidase gene DK-ACO1 gene expression are triggered. Ethylene is then generated and diffused into the pulp, which acts as a secondary signal to stimulate the synthesis of ethylene in the pulp and initiates the transition of ethylene. Soften the fruit.