柑橘CHS基因序列多态性及表达水平对类黄酮生物合成的影响

查尔酮的合成是类黄酮生物合成途径中的一个关键节点。从10个柑橘种质中克隆了查尔酮合成酶(chalcone synthase,CHS)基因,并对其不同时期的果实和叶片中的类黄酮含量进行了测定,分析了CHS基因的序列多态性与类黄酮含量之间的关系;同时通过qRT-PCR检测了CHS基因在不同种质之间以及同一种质的不同组织间的表达差异。结果表明,柑橘CHS基因的核苷酸序列高度保守,相似度达98%以上。聚类分析表明,CHS氨基酸序列的多态性有物种特异性,而且与类黄酮含量有一定的相关性。CHS基因的表达水平在不同种质、部位及生长发育时期有显著差异,这些差异与类黄酮的含量有显著的相关性,说明CHS基因对类黄酮的生物合成有明显影响。

Polymorphism and Expression of Chalcone Synthase Gene in Citrus Related to the Flavonoids Content

Chalcone synthase is one of the most important enzymes in flavonoids biosynthesis pathway. In this study，the CHS genes encoding chalcone synthase were isolated from 10 citrus species. Their expressions in different parts of plant and different time of the development were analysed by qRT-PCR. The flavonoids content at different development stages of fruits and leaves were investigated. The results indicated that in different citrus species，the CHS genes are very conservative with a high level of similarity at 98%. However，polymorphism on amino acid sequence of CHS was found among different citrus species，which demonstrated certain relationship with flavonoids content. The study reveals that expression level of CHS genes significantly different among different species，part of plant and development stages，indicating the CHS gene plays an important role in the biosynthesis of flavonoids in citrus.