ABSTRACT
Anthocyanidin reductase (ANR) is one of the key enzyme in the flavonoid biosynthetic pathway, and its catalytic activity is important for the synthesis of plant anthocyanin. In this study, specific primers were designed according to the transcriptome data of Lonicera japonica Thunb., and the CDS, gDNA and promoter sequences of ANR genes from Lonicera japonica Thunb. and Lonicera japonica Thunb. var. chinensis (Wats.) Bak. were cloned. The results showed that the CDS sequences of LjANR and rLjANR were 1 002 bp, the gDNA sequences were 2 017 and 2 026 bp respectively, and the promoter sequences were 1 170 and 1 164 bp respectively. LjANR and rLjANR both contain 6 exons and 5 introns, which have the same length of exons and large differences in introns. The promoter sequences both contain a large number of light response, hormone response and abiotic stress response elements. Bioinformatics analysis showed that both LjANR and rLjANR encoded 333 amino acids and were predicted to be stable hydrophobic proteins without transmembrane segments and signal peptides. The secondary structures of LjANR and rLjANR were predicted to be mainly consisted of α-helix and random coil. Sequence alignment and phylogenetic analysis showed that LjANR and rLjANR had high homology with Actinidia chinensis var. chinensis, Camellia sinensis and Camellia oleifera, and were closely related to them. The expression levels of LjANR and rLjANR were the highest in flower buds and the lowest in roots. The expression patterns at different flowering stages were similar, with higher expression levels in S1 and S2 stages and then gradually decreased until reaching the lowest level in S4 stage, after a slow increase in S5 stage, the expression levels decreased again. The expression levels of ANR genes in the two varieties showed significant differences in roots, S2 and S5 stages, while the differences in stems, flower buds, S1, S3 and S6 stages were extremely significant. The prokaryotic expression vector pET-32a-LjANR was constructed for protein expression. The target protein was successfully expressed of about 59 kD. This study lays a foundation for further study on the function of ANR gene and provides theoretical guidance for breeding new varieties of Lonicera japonica Thunb.
ABSTRACT
UDP-glucose: flavonoid 3-O-glucosyltransferase (UF3GT) uses flavones, dihydroflavonol or anthocyanin as the acceptor and uridine 5′-diphosphate-sugar as the donor to catalyze the production of flavonoid 3-O-glycoside compounds. Based on sequence homology and transcriptome data, we screened and cloned a UF3GT gene named CtUF3GT (GenBank No. OM948976) from safflower. Biological information analysis demonstrate that CtUF3GT has highly conserved PSPG motif. The open reading frame of CtUF3GT is 1 446 bp, encoding 481 amino acids, with a presumed molecular weight of 52.36 kD and a theoretical isoelectric point of 5.33. Multiple sequence alignment indicate that CtUF3GT has a high homology with UF3GT from Asteraceae, and phylogenetic analysis showed that CtUF3GT clusters with functional identified UF3GTs from other species. The purified recombinant protein glucosylated kaempferol and quercetin to biosynthesis of kaempferol 3-O-glucoside and quercetin 3-O-glucoside, respectively. And CtUF3GT prefered to use kaempferol as substrate. qRT-PCR analysis showed that the UF3GT gene was most highly expressed in flowers, followed by leaves, with very low expression in bracts and stems, and no expression in roots. The expression of UF3GT gene showed a trend of increasing and then decreasing at different stages of flower development. The expression of CtUF3GT gene in safflower with different flower color was highly significant (P < 0.01) at S1, S2, S5, S6 and S7 stages of flower development, in which the expression of CtUF3GT in white safflower was 5.3 and 3.1 times higher than that in red safflower at S6 and S7 stages. This study lays the foundation for further exploring the role of CtUF3GT in the mechanism of safflower flavonoid secondary metabolite biosynthesis and accumulation.