SSR analysis of soybean (Glycine max (L.) Merr.) genetic relationship and variety identification in Thailand

摘要

Simple sequence repeat (SSR) analysis was used to determine the genetic diversity and relatedness among 25 soybean (Glycine max (L.) Merr.) genotypes (15 certified varieties, 8 breeding lines and 2 plant introductions) in Thailand. Eleven SSR primer pairs could amplify polymorphic SSRs from all of these genotypes. A total of 53 alleles with an average of 4.82 alleles per locus were detected. The polymorphic information content (PIC) among genotypes varied from 0.13 (Soy satt 285) to 0.88 (Soy satt 173) with an average of 0.60. Pairwise coefficients of genetic similarity between all genotypes ranged from 0.73 to 1.00 with an average of 0.88. These eleven SSR markers successfully distinguished 23 of the 25 soybean genotypes, with the exception of a pair of closely related breeding lines from the same cross. Allelic variation was observed at the two SSR loci associated with agronomic traits. In addition, only the five most polymorphic SSR markers were able to clearly identify all 15 certified varieties and would be useful for DNA fingerprinting. Unweighted pair-group method arithmetic average (UPGMA) analysis allocated the genotypes in 4 major clusters containing 19, 2, 2 and 2 genotypes, respectively. The largest cluster (I) was divided into subclusters Ia and Ib consisting of 13 and 6 genotypes, respectively. The genetic relationships among genotypes generally agreed with known pedigrees. Principal coordinate analysis (PCoA) confirmed the separation of soybean genotypes into four groups comparable to those from UPGMA analysis. However, genotypes in subclusters Ia and Ib were more clearly separated. These results suggest that SSR markers are efficient for measuring genetic diversity and relatedness as well as identifying varieties of soybeans. Genetic diversity and relationship assessments among soybean genotypes in Thailand could provide useful information for efficient utilization of these materials, especially for genetic improvement. ___________________________________________________________________________ .