Kang Xiaofei, Mikami Riho, Akita Yusuke
Department of Life Science and Green Chemistry, Graduate School of Engineering, Saitama Institute of Technology, 1690 Fusaiji, Fukaya, Saitama 369-0293, Japan.
Plant Biotechnol (Tokyo). 2021 Jun 25;38(2):263-268. doi: 10.5511/plantbiotechnology.21.0308a.
Wild cyclamen () is considered as a precious breeding material for the development of new cultivars. Malvidin 3,5-diglucoside is the main anthocyanin in the petals of , whereas the F1 progeny of the × cultivars cross contains 3,5-diglucoside-type anthocyanins as the main pigment. The anthocyanin 5--glucosyltransferase (A5GT) enzyme is responsible for the glycosylation of the A ring of anthocyanin at the 5--position, which implies that the expression of is dominant in the petals of × cultivars. Here, we isolated the complete open reading frame of the gene from (). Results of qRT-PCR revealed that shows tissue-specific expression, with strong expression in fully opened petals and weak expression in young petals. In vitro enzyme assay showed that when uridine diphosphate glucose was used as the sugar donor, recombinant Cpur5GT could catalyze the glycosylation of 3-glucoside-type anthocyanidins at the 5--position, but when uridine diphosphate galactose was served as glycosyl donor, the reaction could not be performed. These results demonstrate that Cpur5GT exhibits valid anthocyanin glucosylation activity and could be used to analyze the mechanism of A5GT-mediated flower coloration in cyclamen in future studies.
野生仙客来（）被认为是培育新品种的珍贵育种材料。锦葵色素3,5 - 二葡萄糖苷是仙客来花瓣中的主要花青素，而仙客来品种间杂交的F1后代含有3,5 - 二葡萄糖苷型花青素作为主要色素。花青素5 - 葡萄糖基转移酶（A5GT）负责花青素A环在5 - 位置的糖基化，这意味着在仙客来品种间杂交的花瓣中该基因的表达是显性的。在此，我们从仙客来（）中分离出了该基因的完整开放阅读框。qRT - PCR结果显示该基因具有组织特异性表达，在完全开放的花瓣中表达强烈，在幼嫩花瓣中表达较弱。体外酶活性测定表明，当以尿苷二磷酸葡萄糖作为糖供体时，重组Cpur5GT可以催化3 - 葡萄糖苷型花青素在5 - 位置的糖基化，但当以尿苷二磷酸半乳糖作为糖基供体时，反应无法进行。这些结果表明Cpur5GT具有有效的花青素糖基化活性，可用于未来研究分析仙客来中A5GT介导的花色形成机制。
