Characterization of the genetic structure and diversity of maize (Zea mays L) landrace populations from Mexico

Maize (Zea mays L) is a globally important crop. In Mexico, its center of origin and diversity, it forms part of the culture and staple diet of present-day towns. This condition has allowed the development of a large number of maize landraces. In southern Mexico, in the states of Yucatán, Quintana Roo, Campeche and Chiapas, little attention has been given to the diversity potential that landraces represent in order to make best use of them. This work therefore characterized the genetic structure and diversity of 16 maize landrace populations from the southern region of Mexico using ISSR markers. A total of 69 loci were generated with 100% polymorphism. The analysis revealed the formation of two groups with geographical and genetic origins in the Yucatán Peninsula and the state of Chiapas. Wide genetic diversity was found for the entire sample of assessed populations (He = 0.40 and I = 0.54), as well as in the groups formed (He = 0.36, I = 0.52 and He = 0.35, I = 0.50 respectively). At the population level within each group, the populations that formed the Yucatán Peninsula group had greater mean diversity values than in the Chiapas group (He = 0.33, I = 0.36 and He = 0.32, I = 0.35 respectively). Based on this information, it is recommended to develop in-situ conservation programs and to increase the existing ex-situ collections in the region that allow us to enhance the germplasm of the maize landraces of Mexico in breeding programs