论文部分内容阅读
猕猴桃(Actinidia chinensis)具有很高的营养和保健功能,然而其果实贮藏过程中容易软化从而影响其商品品质。多聚半乳糖醛酸酶(polygalacturonase,PG)参与果胶的降解,与果实软化密切相关。为了解猕猴桃贮藏过程中果实软化的分子机理,本研究以米良一号猕猴桃果实为材料,研究室温、低温和脱落酸(abscisic acid,ABA)处理下猕猴桃果实硬度、可滴定酸、可溶性固形物和维生素C等生理指标变化,同时对其多聚半乳糖醛酸酶基因(AcPG)进行克隆(Gen Bank登录号:KY 129958)、生物信息学和表达分析。结果表明,在贮藏过程中,猕猴桃果实硬度和可滴定酸含量总体呈下降趋势,而可溶性固形物和维生素C含量逐步上升,其中ABA处理加快了猕猴桃果实软化,而低温贮藏可减缓猕猴桃硬度下降;克隆获得猕猴桃AcPG开放阅读框1 545 bp,编码514个氨基酸;生物信息学分析发现,AcPG属于不稳定蛋白,含有信号肽、跨膜螺旋结构、多聚半乳糖醛酸酶保守结构域和多个磷酸化位点,亚细胞可能定位于细胞壁上,进化上AcPG与其他物种的亲缘关系较远;qRT-PCR分析发现,室温和低温贮藏过程中猕猴桃软化后,AcPG的相对表达量也相应降低,但AcPG能够明显响应ABA诱导。研究认为,低温贮藏有利于猕猴桃采后保鲜和化学品质保持,且AcPG参与了猕猴桃果实软化过程。实验结果为进一步利用分子生物学技术研究猕猴桃果实软化提供了理论依据。
Actinidia chinensis has high nutritional and health care functions, however, its fruits are easily softened during storage to affect the quality of their products. Polygalacturonase (PG) is involved in the degradation of pectin, which is closely related to fruit softening. In order to understand the molecular mechanism of fruit softening during the storage of Actinidia deliciosa, we studied the effects of room temperature, low temperature and abscisic acid (ABA) on the fruit firmness, titratable acidity, soluble solids, Vitamin C and other physiological changes, at the same time its polygalacturonase gene (AcPG) was cloned (Gen Bank accession number: KY 129958), bioinformatics and expression analysis. The results showed that during storage, the firmness and titratable acid content of Actinidia chinensis decreased while the contents of soluble solids and vitamin C increased gradually. The ABA treatment accelerated the softening of Kiwifruit fruit, while the low temperature storage decreased the hardness of Kiwifruit. Cloning of the Kiwi fruit AcPG open reading frame 1 545 bp, encoding 514 amino acids; bioinformatics analysis found that AcPG is unstable protein, containing the signal peptide, transmembrane helix structure, polygalacturonase conserved domains and multiple At the phosphorylation site, the subcellular localization of AcPG in the cell wall may occur. AcPG is evolutionarily distantly related to other species. The qRT-PCR analysis showed that the relative expression of AcPG in the softened kiwifruit at room temperature and low temperature also decreased, However, AcPG was able to respond significantly to ABA induction. Studies suggest that low temperature storage is conducive to post-harvest preservation and chemical quality of kiwifruit, and AcPG is involved in the softening process of kiwifruit. The experimental results provide the theoretical basis for the further use of molecular biology techniques to study the fruit softening of kiwifruit.