Relationships among teosinte populations (Zea spp.) from Mexico, Guatemala and Nicaragua

Teosinte populations representing all known races, species and subspecies were characterized in order to better understand their relationships and contribute to resolve the taxonomy of the genus Zea. Ninety-five teosinte accessions were grown during the summer of 2011 under greenhouse conditions at the Centro Universitario de Ciencias Biologicas y Agropecuarias (CUCBA). Eighteen morphological and physiological characters as well as 21 climatic descriptors were evaluated using Cluster Analysis and Principal Component Analysis (PCA). The combined data sets of morphological, physiological and climatic variables and the multivariate analysis helped to describe the complexity of the relationships between populations of different teosinte species and different geographical regions of Mexico and Central America. In addition to advancing the taxonomy of teosinte, the most important morphological and climatic variables defining the relationships were identified, based on the length of eigenvectors derived from PCA. The Balsas race of teosinte had the most variable morphology and adaptation. Within subsp. mexicana, the races Chalco, Nobogame and Durango are clearly differentiated. Results show that species, subspecies and race limits are as following: Zea nicaraguensis should be considered a subspecies of Zea luxurians, while Zea luxurians from Oaxaca and Zea diploperennis from Nayarit are two taxa different from the rest. Additionally, Durango is an independent race from the Mesa Central and subsp. parviglumis could be divided into two races, one including populations adapted to altitudes below 1000 m altitude, the others adapted to altitudes from 1000 to 1800 m above sea level.