Teosintes

Teosintes are several wild grasses in the genus Zea, native to the highlands and valleys of Mesoamerica. They are the closest wild relatives of cultivated maize (Zea mays). The best-known taxa are Zea mays ssp. parviglumis (Balsas teosinte) and Zea mays ssp. mexicana (Mexican teosinte).

Teosintes are annual grasses with multiple branched inflorescences and small ears located on the upper parts of the plant. The ears contain a few kernels enclosed by tough glumes, and the seeds shatter easily at maturity, aiding dispersion. Maize, in contrast, bears a large central ear with many kernels that typically stay on the cob.

They occur across a range of elevations in Mexico and adjacent Central America, from valleys to montane slopes, and are adapted to diverse moisture conditions. They are wind-pollinated and readily cross with maize, which has facilitated gene flow between cultivated and wild populations.

Domestication of maize from teosinte began around 9,000 years ago in the Balsas River Basin of southwestern Mexico. Selection led to loss of seed shattering, larger and more prevalent ears, and changes in plant architecture. Key domestication genes include tb1, which reduces branching, and tga1, which alters kernel casing, forming the maize phenotype known today.

Teosintes remain important as genetic resources for maize breeding, providing diversity for disease resistance, drought tolerance, and other traits. They also serve as a model system for studying crop domestication and genome evolution. Conservation of wild teosinte populations is increasingly emphasized to preserve this genetic reservoir.