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Genetics Section

Reagon, Michael [1], Quilloy, Sheila Mae [2], Snow, Allison [1], Cohen, Michael [3].

Estimating the gentic diversity of perennial wild rice, Oryza rufipogon, in the Mekong Delta of Vietnam.

Genetic diversity maintained in populations of wild relatives of cultivated rice in Asia is an important source of breeding material for crop improvement. This is especially true of Oryza rufipogon, the progenitor of domesticated rice. Conservation of genetic resources is a high priority and due to financial and other constraints, sampling schemes that optimize available resources need to be developed. In this study we examined the potential for microsatellite markers to identify areas of conservation interest and elucidate mechanisms that affect diversity. Estimates of genetic diversity and population structure were obtained by screening 378 individuals from 19 O. rufipogon populations (~20 individuals per population) distributed throughout the Mekong Delta of Vietnam. A hierarchal sampling scheme was utilized that separated populations based o­n habitat type (acid sulfate soils, high salinity and freshwater sites) and geographic location (Northeast and Southeast Mekong). Two additional populations were located in Tram Chim National Park. Moderately high levels of genetic diversity were observed at the population level as determined by standard estimates of diversity. The Tram Chim populations were the most diverse, each containing unique alleles, multi-locus genotypes and higher levels of allelic richness. Habitat did not have a statistically significant effect o­n genetic diversity estimates. Although O. rufipogon populations are highly differentiated genetically, we could not find evidence for isolation by distance. Neighbor joining trees based o­n genetic distances revealed some structuring, but Mantel tests showed o­nly low correlations between genetic distance, geographic distance, or habitat type. These data suggest that individual populations may be important sources of unique genetic variation and therefore of conservation interest. Each O. rufipogon population in the Mekong therefore is potentially a significant ‘conservation unit’.

1 - Ohio State University, Depatment of Evolution, Ecology and Organismal Biology, 318 W. 12th Ave., Columbus, Ohio, 43210-4321, United States
2 - International Rice Research Insititute, Los Banos, Laguna,, , Phillipines
3 - University of Alberta, 114 St - 89 Ave, Edmonton, Alberta, T6G 2M7, Canada

Oryza Rufipon
Mekong Delta, Vietnam
genetic diversity
Rice Germplasm.

Presentation Type: Poster
Session: 32-57
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:807

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