紫蕚S-腺苷甲硫氨酸合成酶基因(HvSAMS)的克隆与表达分析

Cloning of HvSAMS gene from Hosta ventricosa flowers and its expression analysis

利用RACE结合RT-PCR技术从紫蕚花中克隆出S-腺苷甲硫氨酸合成酶基因的全长,命名为Hv SAMS。该c DNA全长1 704 bp,ORF为1 191 bp,不含内含子,编码396个氨基酸的多肽。多种植物SAMS的氨基酸序列多重比较分析表明,Hv SAMS与牛奶子、木石斛和石蒜的同源性高达95%,具有SAMS蛋白典型的保守域,且与唐菖蒲的亲缘关系最近。半定量RT-PCR分析显示,Hv SAMS在花和叶中的表达高于根,茎中表达弱;Hv SAMS表达水平在衰花期呈极显著下降,在机械伤害的叶片中迅速显著上升。因其表达变化与乙烯的释放量相关性不大,表明Hv SAMS没有参与乙烯的生物合成。

The full-length of c DNA of SAMS gene from Hosta ventricosa flowers was obtained by RACE and RT-PCR,which was designated as Hv SAMS. Its open reading frame has 1 191 bp and is not interrupted by any intron,encoding a polypeptide of 396 amino acids. Multiple alignment analysis based on the amino acids indicated that Hv SAMS had the similarity of 95% with that from Elaeagnus umbellata,Dendrobium crumenatum,and Lycoris radiata. Phylogenetic analysis showed that Hv SAMS had the closest relation with that from Gladiolus grandiflorus. The expression patterns of Hv SAMS were investigated by means of semi-quantitative RT-PCR. Hv SAMS was expressed highly in flowers and leaves,moderately in roots,but poorly in stems. Hv SAMS transcript was significantly down-regulated in senescing flowers,but significantly up-regulated in wounded leaves. Hv SAMS may not be involved with ethylene production because the changes in Hv SAMS expression were not closely related to ethylene emission.