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本研究以杨树和拟南芥α微管蛋白氨基酸序列为探针,利用本地化BLAST工具搜索柳树全基因组数据库,根据搜索所获序列克隆旱柳和龙爪柳α微管蛋白基因。通过q RT-PCR技术分析不同柳树组织中α微管蛋白基因的表达水平,并利用Bio Edit和MEGA5软件分别进行序列相似性和系统发育分析。结果显示,两种柳树各有8个α微管蛋白基因。柳树种内两两基因间核苷酸和氨基酸序列相似性分别在78.3%和88.4%以上,种间α微管蛋白氨基酸序列相似性在88.2%以上,而柳树与其它植物间的α微管蛋白氨基酸序列相似性在85.1%以上。我们还发现,半数α微管蛋白都包含一个C末端甲硫氨酸、亮氨酸、谷氨酸或谷氨酰胺,而不是更为典型的酪氨酸。在系统发育分析中α微管蛋白分为两类,说明这些基因可能起源于不同的祖先。C末端为Y型的TUA1基因在柳树一年生枝条基部、中段、伸长区和茎尖中高度表达,据此推测它们可能参与柳树木质部的发育过程。柳树TUA基因家族高度的序列相似性、C末端多样性和不同的表达模式可能赋予了细胞壁形成的灵活性,这对多年生木本植物的适应性具有重要意义。
In this study, the amino acid sequences of the α-tubulin of poplar and Arabidopsis were used as probes to search the willow genome-wide database by using the BLAST tool. The α-tubulin genes of A.sinensis and A.sinensis were cloned according to the search sequence. The q-RT-PCR technique was used to analyze the expression of α-tubulin gene in different willow tissues. Sequence alignment and phylogenetic analysis were performed using Bio Edit and MEGA5 software. The results showed that the two willow trees each have eight α-tubulin genes. The nucleotide and amino acid sequence identities of the two genes within the willow species were 78.3% and 88.4%, respectively. The similarity of the amino acid sequence of the α-tubulin in the interspecific hybrid was over 88.2%, while the α-tubulin Amino acid sequence similarity of 85.1%. We also found that half of the alpha tubulin contains a C-terminal methionine, leucine, glutamate, or glutamine rather than the more typical tyrosine. In phylogenetic analysis, α-tubulin is divided into two groups, indicating that these genes may originate from different ancestors. The C-terminal TUA1 gene was highly expressed in the base, middle, elongation and shoot tips of annual branches of willow, suggesting that they may be involved in the development of the xylem of willow. The high degree of sequence similarity, C-terminal diversity and different expression patterns of the willow TUA gene family may confer flexibility to cell wall formation, which is of great importance to the adaptability of perennial woody plants.