USING GENETIC DIVERSITY OF IMPROVE QUANTITATIVE DISEASE RESISTANCE AND AGRONOMIC TRAITS OF CORN
Location: Plant Science Research
Title: Three New Teosintes (Zea spp., Poaceae) From Mexico
| Sanchez-Gonzales, J - |
| DE La Cruz, L - |
| Vidal, V - |
| Parra, R - |
| Taba, S - |
| Santacruz, F - |
| Sood, S - |
| Ruiz, J - |
| Carvajal, S - |
| Aragon, F - |
| Chavez, V - |
| Morales, M - |
| Barba, R - |
Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 15, 2011
Publication Date: September 1, 2011
Citation: Sanchez-Gonzales, J.J., De La Cruz, L., Vidal, V.A., Parra, R.J., Taba, S., Santacruz, F., Sood, S., Holland, J.B., Ruiz, J.A., Carvajal, S., Aragon, F., Chavez, V.H., Morales, M.M., Barba, R. 2011. Three New Teosintes (Zea spp., Poaceae) From Mexico. American Journal of Botany. 98:1537-1548.
Interpretive Summary: Maize was domesticated more than 5000 years ago in Southern Mexico from an ancestor that looked much more like a bunch of grass than modern corn. The closest living relatives of maize are the teosintes, grass species restricted to Mexico and Central America that represent the modern remnants of the ancestral gene pool from which maize was domesticated. Different teosinte species have been identified and classified in the past 100 years, and all are grouped in the same genus as modern corn, Zea. New populations of teosinte were discovered in Mexico that appeared similar to previously identified Zea species but with some unusual plant characteristics and climate adaptations. These new populations were compared to previously named species on the basis of their growth habit, size, leaf shape, and seed type; their ecological adaptation; and their DNA fingerprints. These comparisons all indicate that the new populations are distinct from previously named Zea species, therefore they were named as new species. These species are rare and will require careful conservation efforts to maintain their populations in the wild.
The discovery of new species of teosinte from México motivated the comparative study of populations from México, Guatemala and Nicaragua through detailed ecogeographic, morphologic, cytogenetic and molecular characterization. The study involved a comparative analysis of morphological, ecogeographic, cytological and molecular characteristics. Phenetic and phylogenetic analyses were performed using morphological and molecular data respectively. Zea huajicoriensis is a perennial diploid species (2n = 20) distinguished primarily by short and early maturity plants, male inflorescences with few or no tassel branches and long spikelets. Zea tabae is a perennial tetraploid species (2n = 40) characterized by tall and late plants, male inflorescences with the highest number of tassel branches and glumes and the lowest number of veins within the perennials. Zea oaxacaensis is an annual diploid species (2n = 20) characterized by male inflorescences with fewer branches, shorter branching space, and longer spikelets than Z. luxurians and Z. nicaraguensis; very tall plants with high thermal requirements for flowering; and very deep seed dormancy. Evidence from multiple independent sources supports the taxonomic separation of three new species from the rest of taxa within the genus Zea. All the new teosinte species are rare and endemic to very small areas; based on observations over the last five years, all populations are threatened and should be subject to special protection.