根据植物中CAD基因保守序列设计引物，以尾叶桉GLU4嫩茎为材料克隆到其CAD基因，命名为EuCAD。序列分析结果表明，该基因gDNA长2200 bp， cDNA长1102 bp，开放阅读区编码356个氨基酸。EuCAD编码的蛋白质序列分析显示，序列中具有完整CAD1保守结构域，并包含NADP结合位点以及2个Zn结合位点。同源性分析结果显示， EuCAD核酸序列与其他5种桉属植物CAD基因同源性达到97％以上， EuCAD编码蛋白与碧桃等植物中CAD蛋白同源性也在79％以上。对EuCAD编码蛋白进行理化性质及结构的生物信息学分析结果显示，该蛋白为一种无信号肽、无跨膜区的酸性蛋白质，二级结构包含典型的α-螺旋和β-折叠，三级结构同源建模显示与拟南芥的AtCAD4同源性极高。系统进化树分析结果显示，该蛋白与桉属、杨属植物亲缘关系较近，与杉科植物较远。%A CAD gene was cloned from the young stem of Eucalyptus urophylla clone GLU4 and named EuCAD by using specific primers based on the highly conserved sequences of plant CAD.Sequence analysis indicated that its gDNA and cDNA sequence were 2 200 bp and 1 102 bp respectively , which open reading frame encoding 356 ami-no acid residues .EuCAD encoding sequence was analyzed , and the result showed it has an entire CAD 1 domain, a NADP binding site and two Zn binding sites .The results of homology analysis showed that EuCAD nucleotide se-quence had more than 97%sequence homology with that of other 5 Eucalyptus, and EuCAD encoding protein had more than 79 %homology with that of Prunus persica and others.The physicochemical property and structure of EuCAD encoding protein were analyzed using bioinformatics tools .The result showed it was an acidic protein with-out signal peptide or transmembrane domain , and its secondary structure has typical α-helix and β-sheet.Tertiary structure modeling showed it was most similar to AtCAD 4 in Arabidopsis thaliana.Phylogenetic analysis showed that it has close relative relation with Eucalyptus and Populus, but distant relation with Taxodiaceae .
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