关键词: GA20-氧化酶, 株高, 蒺藜苜蓿, 赤霉素

Abstract: GA20-oxidase (GA20ox) is a key rate-limiting enzyme in the synthesis of gibberellic acid (GA). In order to study the function of GA20ox gene in Medicago truncatula, the amino acid sequence alignment of GA20ox of Arabidopsis thaliana and Medicago truncatula was carried out by bioinformatics methods, and the phylogenetic tree of the families was constructed. The results showed that there were three MtGA20ox, which were MtGA20ox1, MtGA20ox7 and MtGA20ox8, respectively. They had highly homologous to AtGA20ox, and each of them contained a conserved 20G-FeⅡ_Oxy domain. Further, the results of transcript analysis indicated that the expressions of MtGA20ox1, MtGA20ox7 and MtGA20ox8 were tissue specific. Meanwhile, the result of subcellular localization indicated that MtGA20ox1, MtGA20ox7 and MtGA20ox8 proteins were probably localized in nucleus and cytoplasm. In order to comprehend the function of MtGA20ox, two mutants with retrotransposon Tnt1 inserted in MtGA20ox7 and one mutant with retrotransposon Tnt1 inserted in MtGA20ox8 were obtained. The phenotypic observations and data statistics of the three mutants manifested that there were no significant changes in the plant height compared with the wild type. This might be due to the functional redundancy of the three MtGA20ox genes. Results of this study had a certain reference value for studying the function of GA20ox and the regulation of gibberellin on plant height in Medicago truncatula.

Key words: GA20-oxidase, plant height, Medicago truncatula, gibberellic acid