Genetic characterization of Northern Flints and Flours maize (Zea mays L. spp. mays) with isozyme, SSR, and morphological markers

摘要

The Northern Flints and Flours (NF), one of the more important races for maize breeders and scientists, is one of the progenitors of Corn Belt Dents (CB). Despite its importance this race is not well-characterized. Therefore, an assessment of the utility of different methods for genetic characterization of the NF was conducted. Genetic variation in 40 representative germplasm accessions of the racial groups NF, CB, and Southern Dents (SD), maize from the southwestern US and northern Mexico, and maize intermediate between the NF and the other groups, were evaluated with morphological, isozyme and SSR markers. SSR loci proved to be powerful genetic markers for studying genetic diversity and divergence in maize.;As assessed by gene diversity statistics, SSR were more polymorphic (\u3eH[subscript u])1 with more alleles per locus (\u3eA), and a higher proportion of polymorphic loci (\u3eP[subscript 95%]) than isozyme markers in maize. The degree of inter-accessional and inter-racial differentiation in NF strongly support its recognition as a distinct race. The NF are characterized by a high degree of inter-accessional differentiation. The racial groups studied herein differed primarily by the frequencies of the most common isozyme and SSR alleles, rather than by diagnostic unique or rare alleles. Patterns of isozyme and SSR allelic content and phenetic analysis of marker data indicated that NF and SD are extraordinary divergent inter se.;Phenetic analyses of joint morphological, isozyme, SSR data sets yielded results more congruent with the history of these races and previous studies. Distributional patterns of isozyme and SSR alleles, results of independent phenetic analyses of morphology, isozymes, and SSRs and joint analyses support Galinat and Gunnerson\u27s (1963) hypothesis that NF originated from northwestern Mexico maize that diffused through the southwestern US to the northeastern US.