Wednesday, November 7, 2007
279-8

Molecular Characterization of Maize Landraces and Various Subspecies of Teosinte from Mexico and Central America.

Susanne Dreisigacker1, Sukitoshi Taba1, Claudia Bedoya1, Jorge Franco2, Alain Charcosset3, Celine Mir3, Shihuang Zhang4, Chaun-Xiao Xie4, B.M. Prasanna5, Sarah Hearne6, Zachary Muthamia7, Mohamad Yunus8, Chaba Jampatong9, Bui Mahn Cuong10, and Marilyn Warburton1. (1) CIMMYT, CIMMYT Apartado #370, PO Box 60326, Houston, TX 77205, (2) Facultad de Agronomia, Universidad de la Republica, Ave. Garzon 780, Montevideo, Uruguay, (3) INRA-CNRS-UPS-INAPG, Station de Génétique Végétale, Gif sur Yvette, Ferme du Moulon,, France, (4) Institute of Crop Breeding and Cultivation, Chinese Academy of Agricultural Sciences, 30 Baishiqiao Road,, Beijing, China, (5) Division of Genetics, Indian Agricultural Research Institute, New Delhi, India, (6) IITA, P.O. Box 30709, Nairobi, Kenya, (7) National Genebank, Kenyan Agriculture Research Institute, PO Box 30148, Nairobi, Kenya, (8) Agency for Agriculture Research and Development, Indonesian Department of Agriculture, Jl Tentara Pelajar 3A, Bogor, Indonesia, (9) National Corn and Sorghum Research Center, Bangkok, Thailand, (10) Phung town,Danphuong dist, National Maize Research Institute of Vietnam, Hatay, Vietnam

Teosinte (Zea sp.) is the closest related species to maize, (Zea mays mays), and includes maize’s progenitor, Zea mays ssp. parviglumus.  Previous characterization studies generally compare subspecies of teosinte, or maize with few subspecies of teosinte. Diversity within maize landraces may be influenced by selection, drift, and post domestication gene flow where maize is sympatric with different teosinte subspecies (Mexico and Central America).  This study was undertaken to compare the diversity of 20 teosinte populations (representing 7 subspecies) with the diversity of 10 maize landraces from sympatric countries and 10 maize landraces from Asia, that have been separated from teosinte growing regions for several centuries.  Twenty-five SSR markers were used to characterize 15 individuals per teosinte or maize population, using a bulking strategy to calculate allele frequencies in each population.  The relationships between the teosinte species in this study were in agreement with previously published results, with the addition of some subspecies not previously studied now located on the dendrogram.  The majority of the maize landraces clustered closest to one parviglumus population, as predicted, but not all.   The diversity within the cultivated maize landraces was extensive, even compared to the diversity in the wild species.  Of a total of 386 alleles identified in the data set, 138 (36%) were unique to the teosinte species, and 38 (1%) were unique to maize.  Of these, 33 alleles were present only in the Asian maize, 5 were present in both Asian and Mexican maize landraces but not teosinte, and 48 (12%) were present in teosinte and sympatric maize populations, but not Asian.  The results indicate diversity in teosinte that has not been available to exploitation in maize improvement, and hint at drift in the Asian populations and the probability of diversity in maize being influenced by gene flow directly from wild maize subspecies.

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