利用荧光SSR分析中国糜子的遗传多样性和群体遗传结构

【目的】利用荧光SSR研究中国糜子的遗传多样性与群体遗传结构,为糜子品种改良、种质创新和资源利用提供依据。【方法】用不同地理来源且表型差异较大的6份糜子材料对SSR引物进行筛选,通过变性聚丙烯酰胺凝胶电泳获得条带清晰、稳定性好、多态性高的糜子SSR引物,对筛选出的引物5′末端进行6-FAM、HEX、ROX和TAMRA荧光标记,利用基因分析仪检测不同等位变异的扩增片段大小,并以此来分析131份糜子材料的遗传多样性和群体结构。【结果】从202对SSR引物中共筛选出22对扩增稳定、多态性好的SSR引物,能同时适用于传统变性PAGE胶电泳和荧光SSR标记-全自动分析检测技术。22对SSR引物共检测出128个主要等位变异,平均每个位点5.82个;基因多样性指数变化范围为0.3572—0.8132,平均0.6284;多态性信息含量为0.2934—0.8150,平均0.5874;Shannon多样性指数为0.5427—1.7681,平均1.2062。不同生态区糜子种质间遗传距离的变化范围为0.0764—0.7251,平均0.3121,遗传一致度的变化范围为0.4843—0.9265,平均0.7465。其中,北方春糜子区和黄土高原春夏糜子区的遗传距离最小,遗传一致度最高,亲缘关系较近。UPGMA聚类分析显示,北方春糜子区和黄土高原春夏糜子区的材料聚为一类,个体间聚类,东北春糜子区的育成品种和农家种聚类结果一致,黄土高原春夏糜子区的育成品种在多个组群中都有出现。通过绘制K与△K的关系图,K=4时,△K最大,据此将131份糜子材料划分为4个类群,类群Ⅰ代表北方春糜子区;类群Ⅱ主要来自东北春糜子区;类群Ⅲ主要是北方春糜子区,群组Ⅳ主要是黄土高原春夏糜子区。各群体中大部分品种亲缘关系单一,少数品种含有其他组群的遗传成分。基于遗传距离的聚类分析与群体遗传结构分析结果基本一致,表明糜子的遗传差异与地理来源相关。【结论】北方春糜子区和黄土高原春夏糜子区的遗传多样性比较丰富,东北春糜子区的育成品种主要以农家种为遗传背景选育而来,黄土高原春夏糜子区在育种过程中引种资源广泛,与其他生态区存在基因交流。

Genetic Diversity and Population Structure of Broomcorn Millet in China Based on Fluorescently Labeled SSR

【Objective】Genetic diversity and population genetic structure of 131 broomcorn millet accessions in China were analyzed based on fluorescently labeled SSR markers for variety improvement and germplasm innovation as well as effective utilization of broomcorn millet germplasm.【Method】Six broomcorn millet accessions with phenotypical diversity from different geographical origins were used to select SSR markers with highly polymorphism by denaturing polyacrylamide gel electrophoresis. The polymorphic markers were labeled with four fluorescent dyes: 6-FAM, HEX, ROX and TAMRA at the 5' end of forward primers which used in subsequent analyses. The size of each allele locus was determined by DNA Analyzer to estimate the genetic diversity and genetic population structure of the tested accessions. 【Result】 Twenty-two polymorphic and stably amplifying markers were selected for both traditional denaturing PAGE electrophoresis detection and fluorescent SSR labeling-automatic analysis technology. A total of 128 alleles were detected with an average of 5.82 alleles per locus, the gene diversity index, polymorphism information content and Shannon's information index ranged from 0.3572 to 0.8132, 0.2934 to 0.8150 and 0.5427 to 1.7681, respectively, with an average of 0.6284, 0.5874 and 1.2062 respectively. Genetic distance and genetic identity of accessions from different ecotypes were 0.0764-0.7251 (average value is 0.3121) and 0.4843-0.9265 (average value is 0.7465), respectively, the smallest genetic distance was found between NSP ecotype and LPSS ecotype. UPGMA cluster analysis showed that NSP ecotype and LPSS ecotype were clustered into one group. The clustering result of the cultivars and landraces from NES ecotype was consistent, the cultivars from LPSS ecotype were divided into different groups. By plotting the relationship between K and ΔK, ΔK is the largest when K=4. Based on K and △K values, 131 broomcorn millet accessions were grouped four genotypes by the population genetic structure analysis. Group Ⅰ is composed of NSP ecotype. Group Ⅱ consist of NES ecotype. Most accessions of group Ⅲ are from NSP ecotype. Group Ⅳ mainly contain LPSS ecotype. Most of the accessions in same group have same genetic component while only a few accessions contained genetic component of other groups. The analysis result of population genetic structure was consistent with the UPGMA clustering, indicating that the genetic diversity is related to geographical region. 【Conclusion】 There have more abundant genetic diversity in NSP and LPSS ecotype than other regions. The cultivars of NES ecotype were bred mainly from the landraces. The cultivars of LPSS ecotype were introduced from a wide range of resources during the breeding process, harboring genetic exchanges with other ecological regions.