GENETIC STRUCTURE AND DIVERSITY AMONG SWEET CORN (su1-GERMPLASM) PROGENIES USING SSR MARKERS

Genetic structure and diversity among progenies of sweet corn using SSRs loci and a set of 15 progenies of su1 genotypes that represent the diversity available to be currently used by breeding programs was analyzed in the present study. A total of 100 primers were tested, of which 77 were found to be usable in terms of high reproducibility for all sample tested and 13 were polymorphic loci. An average of 2.61 alleles per locus, were detected. The mean gene diversity of all SSR loci is 0.5088. The larger effective number of alleles per locus and the higher gene diversity (He > 0.50) detected in 6 SSR loci suggest that 46% of the 13 SSR loci would be sufficient to the differentiation of the 15 sweet corn progenies. The global deficit of heterozygous plants was low (4.36%) for all SSR loci at S-5 generation. Excess of heterozygous plants occurred mainly in the 5 progenies. The F-ST value indicated that 65.15% of the total variance in allele frequencies at SSRs loci was due to genetic differences among the progenies. The higher H-o value (0.3385) was found in W46 progeny whereas the lowest value (0.00) was recorded in W06 progeny. The highest H-e value was 0.3368 for W28 progeny and the lowest H-e value (0.00) was recorded in W06 progeny. The analysis of genetic structure of su-1 progenies of sweet corn was important for the estimation of genetic distance or similarity among the progenies, and was especially important to identify, the SSR loci with high and low levels of heterozygosity, to identify the progenies at S-5 generation showing 100% of homozygous plants and progenies showing high heterozygosity.