Linoleic acid produced in seeds of Verniciafordii is the direct material for synthesize eleostearic acid through catalysis of FAD2, the researches on FAD2 gene in seed from V. fordii has practical significance on improving yield of eleostearic acid. Taking 16 FAD2 clones in cDNA library of nearly mature V. fordii 'Duinian tung' seeds as materials, CAP3 splicing, BLAST alignment and DNAMAN analysis were carried on. The results showed that the cloned gene sequence was FAD2 full-length cDNA sequence, its length was 1 537 bp. The sequence contained a complete coding sequence, length of 1 146 bp (106-1 255 bp), encoding 383 amino acids. The relative molecular mass of the enzyme protein was 44 144.4 u, jsoelectric point was 8.57. The N end of amino acid sequence had a signal peptide sequence of 6 residues, 5 transmembrane domains, 3 strong hydrophilic sequences existed at the N end, C end and intermediate part, respectively, and the activity center of enzyme was 3 conserved histidine clusters. In system evolution, FAD2 gene in V. fordii had a nearest phylogenetic relationship with V. montana, nearer relationship with Euphorbiaceae plants such as Ricinus communis, Triadica sebifrea, Hevea brasiliensis, Jatropha curcas, and far relationship with Olea europaea, Arachis hypogaea, Sesamum indicum, further relationship with Camelia oleifera.%油桐种子中FAD2催化形成的亚油酸是合成桐油酸的直接原料,研究油桐种子中的FAD2基因对提高桐油酸的产量具有实际意义.将油桐对年桐近成熟种子cDNA文库中的16个FAD2克隆子进行CAP3拼接,再进行BLAST比对,并进行DNAMAN分析,结果表明所克隆的基因序列为FAD2全长cDNA序列,其长度为1 537 bp,含有1个完整的编码序列,长度为1 146 bp( 106～1 255 bp),编码383个氨基酸.酶蛋白相对分子质量44 144.4 u,等电点为8.57,氨基酸序列N端有6个残基的信号肽序列,有5个跨膜结构域,N端、C端及中间各有一段表现为强亲水性,酶活性中心为3个保守的组氨酸簇.在系统进化上,油桐FAD2基因与千年桐的亲缘最近,与蓖麻、乌桕、橡胶树、麻疯树等大戟科植物的亲缘关系较近,与油橄榄、花生、芝麻等植物的亲缘较远,与油茶的亲缘关系更远.
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