普通野生稻凝集素基因的克隆及序列分析

CLONING AND SEQUENCING OF LECTIN GENE FROM COMMON WILD RICE ( O.rufipogon )

以我国普通野生稻基因组 DNA为模板 ,以特异引物经聚合酶链式反应方法扩增出凝集素基因并克隆到 E.coli质粒 p Bluescript SK( +)的 Sma I位点。序列分析表明 ,克隆到的基因片段大小为 781bp,没有内含子 ,编码一条长 2 2 7个氨基酸、分子量约 2 3k D的肽链 ,其中 N-端 2 8个氨基酸是信号肽。与报道的栽培稻凝集素 c DNA序列进行顺序同源性比较 ,发现他们之间有很高的同源性 ( 99.48% ) ,其非编码区第 32位碱基缺失 ,编码区第 163、189和 5 85位各有一个碱基突变 ,但三者均为同义突变 ,并未造成氨基酸序列的变化。鉴于凝集素可能具有抗病、虫害的能力 ,普通野生稻凝集素基因的克隆及序列分析有助于进一步揭示水稻凝集素在植物防御以及其它生理活动中的功能 。

By the aid of polymerase chain reaction, the sequence coding for lectin from common wild rice was isolated and cloned into the SmaI site of pBluescript SK(+).The sequence data showed that the cloned fragment is 781bp. Like most plant lectin genes, there is no intron in the amplified sequence. The open reading frame of the fragment codes a 23kD polypeptide which contains 227 amino acid residues and there is a signal sequence with 28 amino acid residues at its NH 2 terminus.The amplified fragment is highly homologous to the overseas published cDNA sequence with an identity of 99.48%, having three base changes at 163,189 and 585 but without changing amino acids. The establishment of this expression system provides an ideal model for further studies of its biological activities in vitro, especially its defensive functions to pests and diseases, and could provide a useful material for plant genetic engineering.