成熟砂梨果实木葡聚糖转移酶基因PpXTH1的克隆及其在夏季货架期的表达规律

木葡聚糖内糖基转移酶(XTH)通过降解细胞壁中半纤维的主要成分木葡聚糖在果实的软化过程中发挥重要作用。为探明XTH基因与砂梨品种翠冠果实软化之间的关系,本研究以翠冠果肉cDNA为模板,采用RT-PCR和RACE方法,克隆获得了编码砂梨XTH基因的全长cDNA序列(PpXTH1,1 300 bp)。序列分析表明,PpXTH1的5′端和3′端非翻译区分别为125 bp和293 bp,它的开放阅读框为882 bp,编码294个氨基酸,推导的PpXTH1蛋白序列含有XTH蛋白的催化活性部位DEIDFEFL。砂梨PpXTH1与其他植物果实中的XTH蛋白具有较高的同源性,其中与苹果MdXTH1的同源性为98.0%;与猕猴桃AdXTH5的同源性为85.0%;与番茄LeXTH4的同源性为67.6%。分子进化树分析表明,PpXTH1与MdXTH1、PcXTH1、AdXTH5、PtrXTH16A同分在一组,而这些XTH蛋白与果实成熟和细胞壁的次生结构代谢密切相关。在夏季货架期,28~32℃条件下,翠冠果肉中PpXTH1的表达量持续上升,贮藏8 d时其表达量最高,之后缓慢下降,1-MCP对PpXTH1的表达起延缓作用。以上结果说明...

Cloning of an Xyloglucan Endotransglycosylase/Hydrolase Gene (PpXTH1) from Mature Sandy Pear Fruit and Its Expression Characteristics during Summer Shelf Life

Xyloglucan endotransglycosylase/hydrolase(XTH) plays an important role in fruit softening through degrading xyloglucan which is the predominant hemicellulose of cell wall.To reveal the relationship between fruit softening and XTH gene during sandy pear(Pyrus pyrifolia Nakai cv.Cui Guan) fruit ripening,a full length cDNA(1 300 bp) of PpXTH1 was isolated from mature sandy pear fruit using RT-PCR and RACE(rapid amplification of cDNA ends) methods.Sequence analysis showed that the isolated cDNA contained a 125 ...