Detection of genetic diversity of seven maize races from the high central valleys of Mexico using microsatellites


In Mexico there is a broad diversity of maize. To design schemes of genetic improvement and germplasm con¬servation, this diversity must first be assessed. In this context, an analysis of microsatellites was conducted to estimate the degree of variation and to analyze the structure and genetic diversity of seven maize (Zea mays L) landraces from the High Central Valleys of Mexico (Arrocillo Amarillo, Cacahuacintle, Chalqueño, Cónico, Elotes Cónicos, Palomero Toluqueño and Purépecha) as well as the teosinte races Chalco [Zea mays ssp. mexicana (Schrader) Iltis] and Balsas [Zea mays ssp. parviglumis (Iltis and Doebley)]. Seed from 107 accessions kept in Mexican germplasm banks was used. We analyzed 31 SSR loci to estimate genetic variation based on the number of alleles per locus, proportion of polymorphic loci and index of expected heterozygosity, and genetic structure using Wright F statistics. Races were grouped based on principal component and cluster analyses. A total of 636 alleles were identified, averaging 20.52 alleles per locus, 92.75% of which were polymorphic loci. Also found were 100 alleles exclusive of some of the studied populations. Occurrence of these alleles was low, representing 16% of the total alleles found. It was determined that 76.3% of the genetic diversity of the cultivated landraces of the High Valleys of Mexico resides within populations and the remaining 23.7% is between populations. Well-defined groups of the races Cacahuacintle and Purépecha, as well as two groups of the Chalqueño race, were observed. The Purépecha race formed a compact group separate from the rest, while a large sample of the Elotes Cónicos race group was placed intermediately among one of the groups of the Chalqueño race.


Zea mays L; plant genetic resources; germplasm; molecular markers