Cloning and expression of AGL19 gene in two Lonicera macranthoides varieties

AGLl9 is an important regulator for flowering in plants and critical in controlling the morphogenesis of flower organs. The fulllength cDNAs of AGL19in conventional Lonicera macranthoides (Lm-AGL19) and the mutant 'Xianglei' cultivar (Lm-XL-AGL19) were obtained using rapid amplification of cDNA ends and the expression vectors for Lm-XL-AGL19were constructed to investigate the roles of AGL19 in the 'Xianglei' cultivar. Lm-AGL19 (GenBank: MK419948) and Lm-XL-AGL19 (GenBank: MK419948) were isolated from the conventional variety and 'Xianglei' cultivar of L. macranthoides, respectively. Lm-AGL19 is 1274 bp in length, whereas Lm-XL-AGL19 is 1264-bp long, and both include a 654 bp open reading frame, encoding 217 amino acids, which has a highly conserved MADS_MEF2_like domain and a moderately conserved K-box domain, belonging to the type II MADS-box family of genes. Quantitative real-time polymerase chain reaction indicated that the expression levels of these genes at different flowering stages were significantly different, and that the genes were also expressed in stems and leaves. Lm-XL-AGL19 is underexpressed at flowering period 5 that the key time node for corolla expansion and nonexpansion, while LM-AGL19 is overexpressed during this flowering period. AGL19 was speculated to be a functional gene causing different phenotypes in the two L. macranthoides varieties. The successfully constructed plant expression vector provides an experimental reference for further research on the function of this gene and the basis for the excellent phenotype of L. macranthoides 'Xianglei'.