关键词: 苹果, MdMYB10, 过表达, 病毒诱导的基因沉默, 苯丙氨酸代谢

Abstract: MdMYB10 gene plays crucial roles on anthocyanin biosynthesis in apple fruits（Malus × domestica）. However，the effects of MdMYB10 on other polyphenols biosynthesis in phenylalanine metabolism pathway are still unclear. In this study，MdMYB10 was cloned from the peel of‘Pink Lady’apple fruit. The overexpression vector pCAMBIA2301-MdMYB10 and interference vector pTRV-MdMYB10 were constructed respectively to verify the function of MdMYB10. In order to analyze the effect of MdMYB10 on phenylalanine metabolism in the peel of unbagged apple fruit，the overexpression and silence of MdMYB10 was induced by Agrobacterium tumefaciens injection. The results indicated that in the MdMYB10 overexpression apple fruit peel，MdMYB10 expression level was raised 19.62 times，and the expressions of MdPAL，MdCHS，MdF3H，MdDFR，MdANS，MdUFGT，MdFLS and MdANR were up-regulated with varying degrees，but no significant change was found for the MdLAR expression. In the MdMYB10 silenced apple fruit peel，the expression of MdMYB10 was down-regulated by 87%，and the expressions of MdCHS，MdF3H，MdDFR，MdANS and MdUFGT were suppressed in different degrees. Among them，the expression of MdANS and MdUFGT decreased most，with 83% and 82%，respectively. In addition，anthocyanins accumulation in the peel of apple fruits with overexpression vector increased 3.05 times. The content of quercetin-3-O-galactoside，epicatechin，procyanidins B2，chlorogenic acid and coumaric acid increased with varying degrees，and phlorizins concentration did not show significant change. In MdMYB10 silenced apple peel，anthocyanins accumulation decreased by 83%，and quercetin-3-O-galactoside and epicatechin content decreased by 58% and 52%，respectively. Procyanidins B2 and phlorizin concentration did not show significant change. By contrast，chlorogenic acid and coumaric acid content increased by 24% and 21%，respectively. Therefore，MdMYB10 gene not only regulates anthocyanin biosynthesis in apple fruit peel，but also regulates the chlorogenic acid，coumaric acid，quercetin-3-O-galactoside，epicatechin and procyanidins B2 biosynthesis in phenylalanine metabolism. However，no obvious effect was shown on phlorizin biosynthesis.

Key words: apple, MdMYB10, overexpression, VIGS, phenylalanine metabolism