Expression analysis of structural genes related to anthocyanin synthesis in a mutant of ‘Hongyang' kiwifruit

【Objective】The aim of this study was to explore the role of related structural genes in the anthocyanin synthesis in red-fleshed kiwifruit. 【Method】The outer and inner pericarp in a single fruit of ‘HY-09' kiwifruit, a mutant of ‘Hongyang'(Actinidia chinensis Planch. var. rufopulpa C. F. Liang et A. R. Ferguson) with stable red coloration were selected as materials. During the fruit development, the anthocyanin content was determined by pH differential method and the expression of anthocyanin-synthesisrelated structural genes were respectively analysed by qPCR(quantitative PCR) technique. 【Result】The results showed that the anthocyanin can not be detected in outer pericarp during the whole fruit development. However, the anthocyanin was first detected at 67 day after full bloom(DAFB) in inner pericarp and then the anthocyanin content significantly increased along with the fruit development and peaked at 122 DAFB, but then decreased before harvest. Q-PCR analysis of structural genes showed that the level of gene expression in outer pericarp was very low except at 47 day DAFB during the fruit development. In inner pericarp, the expression levels of CHS2, CHI, F3'H1, DFR2, ANS4, F3GGT1 were higher in young fruit period, but then decreased until kiwifruit.harvested The expression level of F3H2 and F3GT1 was highest at 67 day DAFB and remained high during the latter fruit development. Hierarchical clustering analysis suggested F3H2 and F3GT1 clustered together and separated from other genes significantly. 【Conclusion】 The anthocyanin was accumulated only in inner pericarp and the anthocyanin-synthesisrelated structural genes had higher expression level than in the outer pericarp respectively. We suggested that F3H2 and F3GT1 might play important roles in the anthocyanin synthesis process, and it was likely to be key genes of anthocyanin synthesis in kiwifruit.