Cotton genetic resources in the western states of Mexico:: in situ conservation status and germplasm collection for ex situ preservation

The Gossypium hirsutum gene pool from Mexico is one of the primary sources for improvement of most of the Acala and Upland cotton growing in the world today. Mexico is also the center of diversity of the Gossypium genus with 11 of the 13 known diploid Gossypium species of the Western Hemisphere endemic to its boundaries. In 2002 and 2003, the current status of these important genetic resources was surveyed, and germplasm was collected in the western states of Mexico. Information was collected to verify current status and circumscription of the endemic Gossypium species. Sixty years after the first in-depth studies of Gossypium in Mexico, increasing human population, modernization and urbanization have severely reduced the survival of G. hirsutum landraces. Representatives of cotton landraces evidently survive only as curiosities in garden plots or dooryards, or as occasional feral plants. Populations of seven known species, G. aridum, G. barbadense, G. gossypioides, G. hirsutum, G. laxum, G. lobatum, and G. schwendimanii, and one undescribed wild diploid Gossypium taxon were located during the survey. In situ conservation of some of these species is threatened. Samples of the collected germplasm were deposited in the Cotton Collection of the US National Plant Germplasm System where they will be available to scientists worldwide for research, breeding, and education. Additionally, a Gossypium species nursery is being established by the Mexican government for the preservation, and as a working legacy, of this resource. Knowledge of the diversity and, consequently, utilization of the genetic resources in these species cannot be fully realized in situ under current conditions.