植物凝集素是一类能高度特异可逆结合到单糖或寡糖上的蛋白,含有至少一个非催化结构域,近年来在农作物抗虫工程中得到了广泛关注.本文从豆科植物国槐中克隆得到了一个新的凝集素基因SjLectin并初步研究了其对小菜蛾的抗性功能.从国槐幼叶中提取总RNA,采用RT-PCR法分离克隆出SjLectin基因的cDNA片段,该基因在GenBank中登录号为KC140286.1.SjLectin基因全长837 bp,编码279个氨基酸组成的蛋白.该蛋白与其他豆科凝集素的同源性均高达66％以上,属于豆科凝集素家族中的一员.在35S启动子控制下,利用根癌农杆菌介导法转化烟草品种W38,获得了该基因的抗卡那霉素植株.通过PCR和RT-PCR法筛选阳性转基因植株,证明SjLectin基因已经转化到烟草基因组中并在转录水平上得到了有效表达.接虫试验证明,阳性植株对小菜蛾的抑制率平均达62.2％.%Plant lectins can reversibly bind to specific monosaccharides or oligosaccharides and contain at least one non-catalytic domain structure, which have attracted more attention in insect-resistant crop genetic engineering in recent years. In this study, a new plant lectin gene was successfully cloned from Sohora japonica, a member of Leguminosae, and its function of resistance to Plutella xylostella was preliminarily investigated. Total RNA was extracted from young leaves of S. japonica, and a cDNA fragment containing SjLectin gene was cloned and amplified by means of RT-PCR. The gene sequence was accepted and released by GenBank with accession number KC140286.1. Sequence analysis showed that this gene has an open reading frame of 837 bp and encodes a protein of 279 amino acids with 66％ homology to other Legume lectins, indicating that it belongs to the leguminous lectin superfamily. Under the control of the 35 S promoter, the gene was transformed into Tobacco W38 plants by Agrobacterium tumefaciens mediation. Positive transgenic plants were screened by PCR and RT-PCR and SjLectin gene could be effectively expressed at the transcription level. Anti-pest bioassay showed that the control efficacy of positive plants on P. xylostella was 62.2％ on average.
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