西南地区白玉米地方种质资源分布及遗传多样性

Genetic diversity analysis and germplasm resource distribution of white maize landraces in Southwestern China

通过表型性状结合的主成分分析,SSR标记分析和群体结构分析,对50个西南地区白玉米地方品种的种质资源分布及遗传多样性进行了研究。结果表明,白玉米地方品种农艺性状表现出很大差异,主成分聚类将其分为7个类群,大部分品种聚在一个群内,但也有少数品种单独成类;利用筛选出来的51对扩增条带清晰,具有明显多态性的SSR引物,共检测到515个多态性位点,SSR位点的平均多态性位点数为10.1个,每个位点的等位基因数为5～19个,平均为12个,多态信息量(PIC)分布范围为0.764～0.958,平均为0.885,遗传相似系数变幅在0.574～0.840,平均为0.684,标记索引指数(MI)分布范围为3.820～18.208,平均值为9.775。SSR分析将所选品种分为8类,且84%的组合集中在前三大类。从地方品种来源地分析来看,地理位置相似或接近的地方品种大多两两成类,遗传相似系数很高,而群体结构分析显示,白玉米地方品种的群体结构受其地理环境气候的影响。少数地方品种较独立,可以进一步从种质资源方面研究利用。

Characterization of genetic diversity of maize （Zea mays） germplasm is of great importance in maize breeding. The objectives of this study were to investigate genetic diversity and germplasm resource distribution of white maize landraces in Southwest China with phenotype, SSR data and population structure. These maize germplasms varied significantly in all of the measured morphological traits. Principal components cluster analysis showed the 50 accessions were divided into 7 groups, and most of the landraces were clustered into one group. However, a few varieties could be clustered into another single group. Genetic diversity of 50 white maize landraces was tested using bulk DNA samples and 51 microsatellite （SSR） loci distributed on 10 chromo- somes of maize. A total of 515 alleles were detected among the landraces. At each locus, the number of alleles varied from 5 to 19, with an average of 12. Genetic similarity coefficients ranged from 0. 574 to 0. 840, with an average of 0. 684. On the basis of the genetic similarity coefficients, clustering analysis separated the landraces into 8 groups. The landraces collected from the same region were mostly grouped together based the origin data. The population structure indicated that the germplasm resource distribution was related to the geographic information and climatic condition. The results also showed that the genetic resource of those landraces is narrow and single, the genetic diversity is low, and only a few landraces were divided into single groups. So it was important to expand the maize germplasm and the improvement and conservation of maize landrace should be made.