关键词: 蒺藜苜蓿, SE1, 糖基转移酶, 类黄酮合成, 叶绿素合成

Abstract: Glycosyltransferases play an important role in the flavonoid metabolism, which is important for plant development and plant-environment interplay. In order to study the biological function of glycosyltransferase in Medicago truncatula, a series of small and emerald1 (se1) mutants with short plant and dark green leaves by directional screening Tnt1 retrotransposon-tagged lines of M. truncatula was isolated and characterized. The SE1 gene was cloned by PCR-based genotyping of flanking sequence tags (FST) in segregating populations. SE1 encoded a glycosyltransferase that had 52.8% homology with AtUGT84A1, which regulated flavonoid biosynthesis in Arabidopsis. Flavonoid analysis showed that the content of total flavonoids was significantly reduced in the se1 mutants. qRT-PCR analysis revealed that the expression of CHS, F3H and F3’H, key genes of flavonoids synthesis pathway, were down-regulated in the se1 mutants. Subcellular localization showed that SE1 might fulfill its functions in both cytoplasm and nucleus. These data together demonstrated that the glycoltransferase gene SE1 might be involved in the regulation of flavonoid metabolism in M. truncatula, thus influencing M. truncatula growth and development. In addition, the study also revealed that the SE1 gene could negatively regulate M. truncatula chlorophyll biosynthesis.

Key words: Medicago truncatula, SE1, glycosyltransferase, flavonoid biosynthesis, chlorophyll biosynthesis