【摘要】 β-1,3-葡聚糖酶是植物重要的防卫蛋白之一。采用同源克隆法,从16个紫花苜蓿品种的集群DNA中分离到3个苜蓿β-1,3-葡聚糖酶基因的部分基因组编码序列,分别对应于蒺藜苜蓿3个不同的β-1,3-葡聚糖酶基因,并命名为β-1,3-葡聚糖酶基因1、β-1,3-葡聚糖酶基因2和β-1,3-葡聚糖酶基因3。其中,β-1,3-葡聚糖酶基因2和苜蓿β-1,3-葡聚糖酶基因3及其蒺藜苜蓿对应基因与包括β-1,3-葡聚糖酶基因1在内的其他豆科同类基因遗传距离较大。序列变异分析显示,β-1,3-葡聚糖酶基因2的SNP位点间平均距离为255bp,DNA和氨基酸序列均非常保守,表明其在进化中受到了强烈的选择压力。β-1,3-葡聚糖酶基因1的SNP位点间平均距离虽然较小（31bp）,但其全部21个SNP位点均为同义SNP,同时,测序片段仅发现了10个单倍型,远远小于其理论单倍型数目(2²¹)。这表明β-1,3-葡聚糖酶基因1的氨基酸序列高度保守,在功能上非常重要,少量单倍型的存在是为了调节其表达,以使苜蓿适应多种内、外部环境条件。更多还原

【Abstract】 Beta-1,3-glucanase genes are one of the most important defensive proteins in plant.This study aimed to isolate the genomic coding sequences of beta-1,3-glucanase genes by a homology-based cloning method using the bulked DNA from 16 cultivars as materials in alfalfa（Medicago sativa）.Consequently,the part genomic coding sequences of a total of 3 beta-1,3-glucanase genes were isolated,and each of these 3 genes had a corresponding homologous beta-1,3-glucanase gene from Medicago truncatula.They were named as beta-1,3-glucanase gene 1,beta-1,3-glucanase gene 2 and beta-1,3-glucanase gene 3,respectively.Cluster analysis showed that beta-1,3-glucanase gene 2,beta-1,3-glucanase gene 3,and the corresponding genes of these two genes in Medicago truncatula clearly diverged from beta-1,3-glucanase genes from other Fabaceae plants and beta-1,3-glucanase gene 1 found.Sequence vibration analysis showed beta-1,3-glucanase gene 2 had an high average inter-SNP distance with a value of 225 bp,indicating this gene was very conserved and thus suffered from a strong evolutionary selection pressure.beta-1,3-glucanase gene 1 possessed an low average inter-SNP distance with a value of 31 bp,but all of 21 SNP sites from this gene were synonymous.Furthermore,only a total of 10 haplotypes were detected for the fragment sequenced from beta-1,3-glucanase gene 1,which was far less the theoretical haplotype number(2²¹).This indicated that beta-1,3-glucanase gene 1 also was very conservative and had a very important function in alfalfa genome.Preserving a little of haplotypes could help to regulate the expression of this gene,therefore enhance the adaptability of alfalfa to a variety of internal and external environmental conditions.更多还原