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色素苷的合成是红色芒果果实着色的主要代谢途径,黄烷酮3-羟化酶(F3H)基因是花色素代谢途径上的关键酶,属于依赖型2-酮戊二酸的双加氧酶(2-ODD)家族,反应需要2-酮戊二酸、分子氧、铁和抗坏血酸,作用是催化柚皮素C3位羟基化,生成二氢山奈素(dhiydorkaempeforl,DHK)。本研究根据已经报道的F3H基因的序列设计兼并引物,采用RACE方法从芒果的果实中,克隆得到了一个F3H基因,其全长cDNA序列为1 182 bp,开放阅读框为1 092 bp,编码363个氨基酸,分子重量为40.82 k D,等电点为4.88。通过在线软件对其二级结构和三级结构进行了预测。对不同着色芒果品种中的F3H基因的表达进行分析发现:红色的贵妃品种中表达量较高,而绿色的桂七品种中表达量较低。通过系统进化树分析发现芒果中黄烷酮3-羟化酶(F3H)基因编码的蛋白与荔枝、可可、柚子等植物的亲缘关系比较近。
The synthesis of biosynthesis is the main metabolic pathway of red mango fruit coloring. The flavanone 3-hydroxylase (F3H) gene is a key enzyme in anthocyanidin biosynthesis pathway and belongs to the dependent 2-oxoglutarate dioxygenase (2-ODD) family. The reaction requires 2-ketoglutaric acid, molecular oxygen, iron and ascorbic acid to catalyze the hydroxylation of naringenin at position C3 to form dhiydorkaempeforl (DHK). In this study, we designed a pair of primers based on the sequence of F3H gene reported in this paper. A F3H gene was cloned from the mango fruits by RACE method. The full-length cDNA sequence of the F3H gene was 1 182 bp with an open reading frame of 1 092 bp encoding 363 Amino acids, the molecular weight of 40.82 k D, isoelectric point of 4.88. Its secondary and tertiary structures are predicted by online software. The expression of F3H gene in different colored mango cultivars was analyzed. The results showed that the expression of F3H gene in red colored cabbage was higher than that in green cultivars. Phylogenetic tree analysis revealed that the protein encoded by the flavanone 3-hydroxylase (F3H) gene in mango is more closely related to plants such as lychee, cocoa and grapefruit.