ISOZYMATIC PROFILE OF NATIVE MAIZES FROM THE TEHUANTEPEC ISTHMUS, OAXACA, MÉXICO. II. VARIATION WITHIN GROUPS

Abstract

Forty representative maize (Zea mays L.) populations were selected on the basis of information derived from a former study on morphological characterization out of 120 populations native to the Tehuantepec Isthmus, Oaxaca, México, in order to analyze their genetic diversity through polymorphisms of 19 isozyme loci. Native populations corresponded to two groups; the first one was assembled by 21 populations belonging to the Zapalote Chico race, while the second one included 19 populations locally known as Maíz Grande. Both groups were in turn subdivided into three subgroups, identified as early, intermediate, and late maturing. Estimators of genetic diversity showed high values for the group of Maíz Grande populations, with a larger number of alleles per locus, polymorphism and expected heterocigosity, as well as genetic differentiation among their populations larger than Zapalote Chico. Regarding Zapalote Chico, its late subgroup showed the lowest values for the estimators of genetic diversity and genetic differentiation among populations, while the intermediate subgroup had the highest values. In the Maíz Grande subgroups, the early subgroup had the lowest values of genetic diversity and genetic differentiation among its populations, and the late subgroup had a larger number of alleles per locus; nevertheless, the intermediate subgroup had the highest values for polymorphism, expected heterocigosity and a higher genetic differentiation value among its populations.