Genetic variability among Turkish pop, flint and dent corn (Zea mays L. spp. Mays) races: Enzyme polymorphism

To determine magnitude and pattern of genetic variation, 32 Turkish corn ac cessions available from the USDA/ARS North Central T-Regional Plant Introdu ction Station (NCRPIS) collections (Ames, Iowa), representing pop, flint an d dent corn races, different climatic, geographic and topographic areas in Turkey, were identified and, 19 isozyme systems were studied. Thirty-nine a lleles were detected by 19 isozyme loci in 32 accessions. The PGD-2, Mmm-1, GOT-3 and IDH-1 loci were found to be monomorphic in all accessions. Mean number of alleles per locus varied between 1.2 in Balikesir-167949 accessio n to 1.7 in Ankara-177600, Trabzon-185062, Eskisehir-204822 and Samsun-2395 73 accessions. The proportion of polymorphic loci ranged from as low as 15. 8% in Balikesir-167949 to as high as 57.9% in Trabzon-185049 accession. Obs erved heterozygosity was the highest in Adana-183779 and the lowest in Anka ra-204800 accession. Genetic identities ranged from 0.823 for 170881-Kocael i and 167949-Balikesir pair to 0.997 for 182327-Igdir and 168008-Kirklareli pair. Dendrogram constructed by using Nei's genetic distances (1978) revea led three clustering groups, though one of the clusters included only 17088 1-Kocaeli accession. It is concluded that 170881-Kocaeli accession must hav e experienced with intensive selection, inbreeding and/or bottleneck effect s in the past. Corn germplasm managers and breeders could use the results o f the present studies for monitoring genetic resources, accession identific ation, and sampling genetic diversity, but agronomic characteristics of the se corn accessions are also needed for a better utlization of Turkish corn landraces evolved over the years.