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GTP环化水解酶I (GCHI)与氨基脱氧分支酸合酶(ADCS)是植物叶酸合成途径的限速酶,对叶酸的合成起着至关重要的作用。本研究利用cDNA末端快速扩增技术(RACE)结合逆转录PCR方法,克隆获得了紫花苜蓿(Medicago sativa)的GCHI和ADCS编码基因,分别命名为MsGCHI与MsADCS。序列分析结果表明,MsGCHI基因全长1 752 bp,包含1 371 bp的开放阅读框(ORF),编码456个氨基酸;MsADCS基因全长3 324 bp,ORF为2 613 bp,编码870个氨基酸。经同源比对与进化树分析,MsGCHI和Ms ADCS基因编码的氨基酸与蒺藜苜蓿(M.truncatula)的MtGCHI和MtADCS氨基酸序列具有最高的同源性,分别达到98%和96%,与其他植物的氨基酸序列相似度也均在58%以上。实时定量荧光PCR分析结果表明,MsGCHI与MsADCS基因在紫花苜蓿的根、茎、叶中均有表达,但在叶中的表达量都为最高。
GCHI and ADCS are the rate-limiting enzymes in the folic acid synthesis pathway and play a crucial role in the synthesis of folic acid. In this study, GCHI and ADCS coding genes of Medicago sativa were cloned by rapid amplification of cDNA ends (RACE) combined with reverse transcription PCR and named MsGCHI and MsADCS respectively. Sequence analysis showed that MsGCHI gene was 1 752 bp in length and contained 1 371 bp open reading frame (ORF) encoding 456 amino acids. MsADCS gene was 3 324 bp in length and ORF was 2613 bp, encoding 870 amino acids. The amino acids encoded by MsGCHI and Ms ADCS genes had the highest homologies with the MtGCHI and MtADCS amino acid sequences of M.truncatula by homology comparison and phylogenetic tree analysis, reaching 98% and 96% respectively. Compared with other plants The amino acid sequence similarities are also above 58%. Real-time quantitative PCR analysis showed that the MsGCHI and MsADCS genes were expressed in the roots, stems and leaves of alfalfa, but the highest in leaves.