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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。
In order to understand the regulatory effect of ABA on the ripening of pear in the golden twentieth century, the content of endogenous ABA in peel, pulp and seed during fruit ripening was determined by high performance liquid chromatography (HPLC) And RACE technique, two ABA key synthase (NCED) and one key degrading enzyme (CYP707A) genes were cloned from the pear fruit and named as PpNCED1, PpNCED2 and PpCYP707A1 respectively, and their expression analysis was carried out. The results showed that the content of ABA in the peel continued to increase with the ripening of fruit, and the content of ABA in pulp and fruit decreased after 10 days before harvest. In the pericarp and flesh, the expression level of PpNCED2 was significantly higher than that of PpNCED1, and consistent with the trend of ABA content. It was the main gene of ABA biosynthesis in pericarp and pulp. Among the seeds, both PpNCED1 and PpNCED2 are highly expressed, which is the main gene of ABA biosynthesis in seeds. The expression pattern of PpCYP707A1 in peel, pulp and seed was opposite to that of ABA, which was the main negative regulator of ABA content. In summary, ABA may regulate the ripening process of pear fruit in the golden twentieth century, while the content of ABA is regulated by synthase and degrading enzyme genes, and there are differences in the major genes of ABA biosynthesis in different tissues.