Elucidation of modification mechanism of secondary metabolites in plant vacuoles.

在单子叶植物百子莲中发现了酰基葡萄糖依赖性葡萄糖基转移酶（AAGT）基因，拟南芥AAGT在转红叶片中对酰基修饰的具有葡萄糖基残基的花色素苷起作用，表明AAGT反应在植物界普遍存在。对羟基苄基葡萄糖（pHBG）在飞燕草花萼花色素7位的修饰中起着葡萄糖基供体的作用。花色苷violdelphin由三个糖基和两个对羟基苄基（pHBA）残基组成，糖基和pHBA残基交替串联和线性共轭。结果表明，pHBG作为酰基-葡萄糖依赖性酰基转移酶的酰基供体和葡萄糖基供体，AAGT作为Zwitter供体，在形成紫海豚素的反应中起着双重作用。鉴定了UDP-葡萄糖依赖性pHBA葡萄糖基转移酶的基因，并且该活性的丧失导致在花青素的7位上没有修饰。

Acyl-glucose dependent glucosyltransfrase (AAGT) gene was found in a monocot plant, Agapanthus, and Arabidopsis AAGT acted to acyl-modified anthocyanin with glucosyl residues in red turning leaves, indicating that AAGT reaction is common in the plant kingdom. In delphinium sepals, p-hydroxybenzyl-glucose (pHBG) acted as a glucosyl-donor at modification at the 7 position of anthocyanidin. The anthocyanin, violdelphin, consisted of three glycosyl and two p-hydroxybenzyl (pHBA)-residues, conjugated with alternately tandem and linear conjugation of glycosyl and pHBA-residues. In the reaction to form violdelphin, it was revealed that pHBG played a bi-functional role to be acyl donors and glucosyl donors for acyl-glucose dependent acyl-transferase and AAGT as Zwitter donor. The gene for UDP-glucose dependent pHBA glucosyltransferase was identified and the loss of this activity resulted not to modify at the 7 position of anthocyanidin.