利用EST-SSR、IT-ISJ分子标记研究四倍体与八倍体柳枝稷的遗传多样性

柳枝稷是重要的能源植物之一,为研究四倍体Alamo与通过秋水仙素加倍后的八倍体之间的遗传差异,本研究以65份四倍体Alamo与其诱变的八倍体为研究材料,通过EST-SSR与IT-ISJ两种分子标记进行遗传分析。结果表明,EST-SSR引物共扩增出245条带,多态性比率为99.59%,观测等位基因Na为1.9878,有效等位基因Ne为1.1718,基因多样性指数H为0.1308,Shannon信息指数I为0.2388,其中四倍体Alamo的各遗传参数(226条,88.93%,1.8816,1.1823,0.1349,0.2398)多高于八倍体Alamo(217条,92.24%,1.9184,1.1652,0.1228,0.2234)。IT-ISJ引物共扩增出165条条带,多态性比率为96.36%,观测等位基因Na为1.9878,有效等位基因Ne为1.5777,基因多样性指数H为0.3354,Shannon信息指数I为0.4999,四倍体Alamo各项指数(145条,94.55%,1.9333,1.6366,0.3602,0.5280)均高于八倍体Alamo(139条,84.24%,1.7515,1.4377,0.2573,0.3864)。通过UPGMA分析表明,65个柳枝稷材料中四倍体与八倍体没有明显区分开,表明其没有产生明显的遗传分化。通过AMOVA分析表明,EST-SSR和IT-ISJ的遗传变异分别有94.78%和80.76%发生在倍性内,有5.22%和19.24%发生在倍性间,表明柳枝稷倍性间没有明显的差异。

Genetic diversity assessment of tetraploid and octoploid switchgrass using EST-SSR and IT-ISJ molecular markers

Switchgrass is an important bioenergy plant.In this study,the genetic diversity of 65 samples of tetraploid Alamo and mutated octoploid Alamo (using colchicine)was assessed using expressed sequence tag-simple sequence repeat (EST-SSR)and intron-targeted intron-exon splice junction (IT-ISJ)markers.The results showed that EST - SSR primers amplified 245 fragments;the percentage of polymorphic loci was 99.59%,the number of alleles (Na)was 1.9878,the effective number of alleles (Ne)was 1.1718,Nei’s gene diversity (H)was 0.1308,and Shannon’s information index (I)was 0.2388.These genetic parameters for the tetraploid Alamo were as follows:226 fragments;88.93% polymorphic loci;Na,1.8816;Ne,1.1823;H, 0.1349;and I,0.2398.These values were higher than those obtained for octoploid Alamo:217 fragments;92.24% polymorphic loci;Na,1.9184;Ne,1.1652;H,0.1228;and I,0.2234.The IT-ISJ primers ampli-fied 165 fragments and the percentage of polymorphic loci was 96.36%,Na was 1.9878,Ne was 1.5777,H was 0.3354,and I was 0.4999.These parameters for tetraploid Alamo were as follows:145 fragments;94.55% polymorphic loci;Na,1.9333;Ne,1.6366;H,0.3602;and I,0.5280.These values were higher than those obtained for octoploid Alamo:139 fragments;84.24% polymorphic loci;Na,1.7515;Ne,1.4337;H,0.2573;and I,0.3864.A clustering analysis with the unweighted pair-group method with arithmetic means did not clearly separate 68 samples of tetraploid Alamo and octoploid Alamo,which had a low level of genetic differentiation.An analysis of molecular variance showed that 94.78% and 80.76% of genetic diversity occurred within ploidy levels,while 5.22% and 19.24% of genetic diversity occurred between ploidy levels.