牛枝子为胡枝子属中最具耐旱特性的灌木树种,是研究基于单核苷酸多态性(SNP)水平的植物个体间耐旱差异机制的重要材料.以5个种源的天然牛枝子为材料,利用染色体步移技术克隆牛枝子抗旱候选基因LpDREB的全长序列,对LpDREB基因的结构和系统进化进行分析,研究LpDRB基因的组织及诱导表达规律,分析LpDREB基因的SNP分布和类型.研究结果表明:克隆的牛枝子LpDREB基因cDNA片段全长为1 611 bp,具有937 bp的开放阅读框,编码318个氨基酸,包含DREB基因所特有的DREBP/AP2保守区域.LpDREB基因同大豆GmDREB3基因的进化关系最近,但2个基因除保守区域外的其他区域相似性不高.牛枝子LpDREB基因受干旱胁迫诱导表达,在组织器官中的根部表达量最大,其次为叶片,茎中的表达量最少.在天然牛枝子群体中共检测到23个SNP位点,其中启动子及5'端非编码区4个,编码区17个,3'端非编码区2个；23个SNP中,12个属于转换,11个属于颠换；编码区内的17个SNPs位点中,9个属于同义突变,8个为非同义突变,同义突变与非同义突变的比值为1.1.研究结果为基于SNP水平的牛枝子抗旱候选基因的关联分析奠定基础.%Lespedeza potaninii is one of the most drought tolerant Lespedeza species and widely distributed in arid, semi-arid and desert grassland. It is an ideal model plant used for the investigating the individual variation of drought tolerant at single nucleotide polymorphisms (SNP) level. In the present study, the drought tolerant candidate gene LpDREB was cloned from five provenances of L. potaninii by chromosome walking method. The organ- and inducible-expression patterns of the LpDREB gene were also investigated. Furthermore, the gene structure and phylogeny, and SNP type and distribution were characterized. The results indicated that the full length cDNA sequence of LpDREB gene was 1 611 bp containing a 957 bp open reading frame (ORF) which encodes a 318 amino acid residues with a highly conserved DREBP/AP2 domain. Phylogeny analysis revealed that the LpDREB gene had a closest evolutionary relationship with soybean GmDREBS gene in terms of high similarity in the common conserved region. Expression of the LpDREB gene was induced by drought stress and varied in different organs with the highest expression level in roots followed by leaves and stems. In the L. potaninii populations, 23 SNPs were detected. Among them four located in promoter and 5' non-coding regions, and 17 were distributed in the coding region, and two in 3' non-coding region. A total of 12 SNPs were in transitions, while 11 SNPs were in trans versions. For 17 SNPs in the coding region, 9 were synonymous mutation and 8 were non-synonymous mutations, with a ratio of 1. 1. This study paved a foundation for association analysis with drought tolerant candidate genes in L. potaninii at SNP level.
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