Cloning and tissue expression of ABA metabolism enzyme genes of ’Gold Nijisseiki’ pear fruit | ‘金二十世纪’梨果实ABA代谢酶基因克隆及其表达分析

Chinese. 为了解ABA对‘金二十世纪’梨果实成熟的调控作用,本研究采用高效液相色谱法（HPLC）分析测定了果实成熟过程中果皮、果肉和种子内源ABA含量变化,采用RT-PCR和RACE技术从该梨果实中克隆得到了2个ABA关键合成酶（NCED）和1个关键降解酶（CYP707A）基因,分别命名为PpNCED1、PpNCED2和PpCYP707A1,并对其进行了表达分析。结果显示：随着果实成熟,果皮中ABA含量持续增加,果肉和种子中ABA含量于采收前10d达到峰值后下降。果皮和果肉中,PpNCED2表达量显著高于PpNCED1,且与ABA含量变化趋势一致,是果皮和果肉中ABA生物合成的主效基因。种子中,PpNCED1和PpNCED2表达量均很高,是种子中ABA生物合成的主效基因。果皮、果肉和种子中PpCYP707A1表达模式与ABA含量变化趋势相反,是ABA含量变化的主要负调控基因。综上,ABA可能调控‘金二十世纪’梨果实成熟进程,而ABA含量水平是由合成酶和降解酶基因共同调控的,且不同组织中ABA生物合成的主效基因存在差异。

English. To investigate the effect of endogenous hormone abscisic acid（ABA） on the maturation of ’Gold Nijisseiki’ pear fruit,we determined the content of ABA in the peel,pulp and seed with HPLC.The ABA content in the peel was continuously accumulated with fruit maturation,while the ABA content in pulp and seed reached to peak at 10 days before harvest and then declined.Two synthetase genes（PpNCED1,PpNCED2） and one catabolic enzyme gene（PpCYP707A1） were isolated from the pear fruits.Real time RT-PCR analysis revealed that PpNCED2 in the peel and pulp was the major gene for ABA synthesis,whereas both PpNCED1and PpNCED2 which were the major genes in the seed had high expression.The PpCYP707A1 was the negative regulation gene for ABA content.Our results thus suggested that the peel,pulp and seed all could synthesize the endogenous ABA which might regulate the maturation of ’Gold Nijisseiki’ pear fruit.