The use of microsatellites for detecting DNA polymorphism, genotype identification and genetic diversity in wheat

A set of 20 wheat microsatellite markers was used with 55 elite wheat genot ypes to examine their utility ii in detecting DNA polymorphism, (2) in the identifying genotypes and (3) in estimating genetic diversity among wheat g enotypes. The 55 elite genotypes of wheat used in this study originated in 29 countries representing six continents. A total of 155 alleles were detec ted at 21 loci using the above microsatellite primer pairs (only 1 primer a mplified 2 loci; all other primers amplified I locus each). Of the 20 prime rs amplifying 21 loci, 17 primers and their corresponding 18 loci were assi gned to 13 different chromosomes (6 chromosomes of the A genome, 5 chromoso mes of the B genome and 2 chromosomes of the D genome). The number of allel es per locus ranged from to 13, with an average of 7.4 alleles per locus. T he values of average polymorphic information content (PIC) and the marker i ndex (MI) for these markers were estimated to be 0.71 and 0.70, respectivel y. The (GT)(n) microsatellites were found to be the most polymorphic. The g enetic similarity (GS) coefficient for ail possible 1485 pairs of genotypes ranged from 0.05 to 0.88 with an average elf 0.23. The dendrogram, prepare d on the basis of similarity matrix using the UPGMA algorithm, delineated t he above genotypes into two major clusters (I and II), each with two subclu sters (Ia, Ib and IIa, IIb). One of these subclusters (Tb) consisted of a s olitary genotype (E3111) from Portugal, so that it was unique and diverse w ith respect to all other genotypes belonging to cluster I and placed in sub cluster Ia. Using a set of only 12 primer pairs, we were able to distinguis h a maximum of 48 of the above 55 wheat genotypes. The results demonstrate the utility of microsatellite markers for detecting polymorphism leading to genotype identification and for estimating genetic diversity.