Isozyme analysis of 18 Northern Flint populations supports the previously published hypothesis that Northern Flint was derived from maize races of the southwestern U.S. and northwestern Mexico. Isozyme data also show that during its short evolutionary history (approx. 1,000 yr) Northern Flint obtained a degree of genetic differentiation from other North American maize landraces more typical of a separate species than of landraces of the same cultigen. Genetic drift, changes in selection pressure associated with movement into a new environment, and reproductive isolation from other maize races may have contributed to the genetic dissimilarity of Northern Flint.
Twelve plants each of 94 collections of maize (Zea mays L. subsp. mays) representing 34 races from Mexico were analyzed for 13 enzyme systems encoded by 23 loci. This analysis revealed an exceptionally high level of variation within and among the races. We recorded an average of 7.09 alleles/locus and an expected heterozygosity of 0.182. Seventy‐two percent of the isozyme variation resided within collections, and 27% among collections. Races from northern and northwestern Mexico tend to possess higher levels of variation than those from the south. Variation for some isozyme alleles is strongly correlated with altitude. Maize is among the most variable species that have been studied isoenzymatically. Maize has levels of variation comparable to those found in its wild relatives, the teosintes. Principal component and cluster analyses showed continuous variation among the races with no well‐defined racial complexes; however, three weakly differentiated groups were apparent: 1) the high‐elevation Mexican pyramidal races, 2) the northern and northwestern races, and 3) most remaining races including the southern and western low‐elevation dent and flour corns.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.