Genetic structure of Jatropha curcas L. in Mexico and probable centre of origin

The understanding of the genetic diversity and structure of populations of Jatropha curcas in their postulated centre of origin will permit to identify genetic material useful for future improvement of the species. Although it is estimated that Mexico is the likely centre of origin and domestication of J. curcas, so far the “true” centre of origin still has to be found. A representative set of 175 accessions of J. curcas from nine central and southeastern Mexican states (Chiapas, Veracruz, Oaxaca, Michoacán, Morelos, Yucatán, Guerrero, Hidalgo and Puebla), including toxic, non-toxic, and contrasting protein and oil content genotypes was used for diversity analysis by AFLP markers. The results indicate that Mexico has a high genetic diversity of J. curcas; molecular analysis suggests population structuring in the different states where this species is spread. The germplasm from Chiapas, where contrasting protein and oil content genotypes were detected, showed the highest genetic diversity and clearly varies from the accessions from the other states. This is probably the most comprehensive study of diversity of germplasm of J. curcas from Mexico, and together with previous reports on the genetic diversity, biochemistry, morphology and germplasm agronomics of J. curcas from Chiapas, suggest the likelihood that this area is the centre of origin for this species and that domestication took place in the states bordering the Gulf of Mexico, such as Veracruz, Hidalgo, Puebla and Yucatán, where genotypes with low or no phorbol ester content exist.