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高等植物中的△12脂肪酸脱饱和酶是将油酸转化为亚油酸的酶。根据已发表的其他高等植物的FAD2基因的保守序列设计同源引物,通过RT-PCR从玉米幼胚中扩增得到一个特异的cDNA基因片段。通过生物信息学分析,从玉米幼胚cDNA和基因组中均扩增得到1164bpFAD2基因(GenBank登陆号:DQ496227),它编码387个氨基酸,含有完整的ORF框,在ORF框内无内含子。序列联配与树状分析结果表明,FAD2推导的氨基酸序列与其他物种的?12脱饱和酶基因具有同源性。它含有3个组氨酸保守域和2段很长的疏水区,是一个跨膜4次的膜结合蛋白。半定量RT-PCR分析显示FAD2基因在玉米幼胚中表达量最高,在叶、茎、根中亦有低水平表达。
Delta 12 fatty acid desaturase in higher plants is an enzyme that converts oleic acid to linoleic acid. A homologous primer was designed based on the conserved sequences of published FAD2 genes of other higher plants. A specific cDNA fragment was amplified from immature embryos by RT-PCR. Bioinformatics analysis showed that the 1164 bp FAD2 gene (GenBank accession number: DQ496227) was amplified from cDNA and genome of maize immature embryos. It encodes 387 amino acids, contains the complete ORF box and no intron in the ORF box. Sequence alignment and tree analysis showed that the deduced amino acid sequence of FAD2 shared homology with the? 12 desaturase gene of other species. It contains 3 histidine conserved domains and 2 long hydrophobic domains, which is a membrane-bound protein that transmembrane 4 times. Semi-quantitative RT-PCR analysis showed that the expression level of FAD2 gene in maize immature embryos was the highest, and it was also low in leaves, stems and roots.