中文摘要：

膨胀素（expansin）是植物生长发育过程中诱导细胞壁松弛和伸展的重要蛋白。分别采用RACE方法,克隆了小麦（Triticum aestivum）TaEXPB8的4个部分同源基因的全长cDNA,其长度分别为1180、1169、1150和1135bp,依次命名为TaEXPB8-1、TaEXPB8-2、TaEXPB8-3和TaEXPB8-4。研究发现,这些基因的启动子区域均含有预测的生长素顺式作用元件。定位结果显示,TaEXPB8-1的位置无法确定,TaEXPB8-2和TaEXPB8-3定位到同一染色体上的相邻区域,即Bin6AS（0.35～1.00）区域,TaEXPB8-4位于Bin6DS（0.99～1.00）区域。在水稻（Oryza.sativa L.）、玉米（Zeamays L.）和拟南芥（Arabidopsis）基因组的同线性区域也存在膨胀素基因的串联重复,说明TaEXPB8-2和TaEXPB8-3可能为同一基因的两个拷贝,并在双子叶和单子叶植物分化之前已经形成。表达分析结果表明,TaEXPB8基因在小麦初生根的伸长区表达丰度最高,且受外源高浓度生长素处理的抑制,推测其可能在小麦根中起重要作用。

英文摘要：

Expansins are considered to be the key regulators of cell wall extension during plant growth.In the present study,rapid amplification of cDNA （RACE） ends was used to clone the full length cDNA of TaEXPB8 homeologous genes.Four distinct cDNA sequences,with the length of 1180,1169,1150 and 1135 bp were identified and named as TaEXPB8-1,TaEXPB8-2,TaEXPB8-3 and TaEXPB8-4,respectively.Interestingly,putative auxin responsive cis-acting regulatory elements were detected in the promoter region of these four homeologous genes.Further analysis revealed that the chromosome location of TaEXPB8-1 was anonymous.but TaEXPB8-4 was located on Bin6DS （0.99～1.00）.Moreover,TaEXPB8-2 and TaEXPB8-3 were located on same chromosome region Bin6AS （0.35～1.00）,and tandem repeat of expansin genes were also detected in the linear genomic region of rice（Oryzasativa L.）,maize（Zea mays L.）and Arabidopsis.Thus,TaEXPB8-2 and TaEXPB8-3 could be originated from one ancestor gene,suggesting the possibility that these two genes were formed in wheat before the divergence of monocots and dicots.It was shown that TaEXPB8 gene was mainly expressed in elongation zone of wheat primary root,and down-regulated by high concentrations of exogenous auxin treatment,indicating that this gene it might play an important role in wheat root development,especially for root elongation.