Cloning and expression analysis of anthocyanidin 3-O-glucosyltransferase gene in Grape hyacinth

Anthocyanidin 3-O-glucosyltransferase (3GT) is the last key enzyme in the anthocyanin biosynthetic pathway, which can catalyze unstable anthocyanidin into anthocyanin. In this study, we cloned a 3GT gene (designated as Ma3GT from Muscari armeniacum) using the PCR technique. The gene’s cDNA was 1 377 bp long and encoded an open reading frame of 458 aminoacids. Ma3GT showed 55%~64% similarity with the other 3GTs. Phylogenetic analysis indicated that Ma3GT was classified into monocot subgroups of 3GTs, and had the closest relationship with the 3GTs of Freesia hybrid and Iris hollandica. QRT-PCR analysis detected transcripts of Ma3GT in different organs of M. armeniacum. The expression level of this gene was high in the fully opened petals (stage S4), very low in the leaves, and almost zero in the roots and bulbs of M. armeniacum. Andit almost had no expression in all the organs of M. aucheri ‘White Beauty’ and M. armeniacum‘Pink Surprise’. The gene expression was related to the floral developmental stages in M. armeniacum. The transcript level was rarely detectablein the unpigmented buds (stage S1), but increased during the pigment accumulation stages and peaked in the fully opened petals (S4). The expression had significant differences in three cultivars of different colors. The expression level was high in the petals of M. armeniacum, and rarely detectable in the petals of ‘White Beauty’ and ‘Pink Surprise.’ This research will provide informationand theoretical support for the functional study of the Ma3GT gene.