Cloning and Functional Characterization of a Flavonoid Transport-Related MATE Gene in Asiatic Hybrid Lilies (Lilium spp.)

Abstract

Previous studies have suggested that multidrug and toxic compound extrusion (MATE) proteins might be involved in flavonoid transportation. However, whether MATE proteins are involved in anthocyanin accumulation in Lilium is unclear. Here, a flavonoid transport-related MATE candidate gene, LhDTX35, was cloned from the Asiatic hybrid lily cultivar ‘Tiny Padhye’ by rapid amplification of 5’ and 3’ cDNA ends (RACE) and found to encode 507 amino acids. BLASTx results indicated that LhDTX35 showed high homology to the DTX35 genes of other species. Bioinformatics analysis predicted that the protein encoded by LhDTX35 possessed 12 typical transmembrane segments and had functional domains typical of the MATE-like superfamily. Phylogenetic analysis grouped LhDTX35 in the same clade as the DTX35 of other species. Notably, the expression pattern of LhDTX35 was positively correlated with floral anthocyanin accumulation in ‘Tiny Padhye’. A subcellular localization assay showed that the protein encoded by LhDTX35 was plasmalemma localized but not nuclear, indicating that the LhDTX35 gene may function as a carrier protein to transport anthocyanins in Lilium. Functional complementation of the Arabidopsis DTX35 gene demonstrated that LhDTX35 could restore silique-infertility and the anthocyaninless phenotype of an Arabidopsis DTX35 mutant. These results indicated that LhDTX35 might be involved in anthocyanin accumulation in Lilium.