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

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 chromosomes 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.