Abstract Detail

Charles Heiser Special Contributed Paper Session

Pusadee, Tonapha [1], Schaal, Barbara [1], Rerkasem, Benjavan [2], Jamjod, Sansanee [2].

Population structure of Oryza sativa primary gene pool in Thailand.

Thailand lies partly in the center of diversity and domestication of Asian rice (Oryzasativa). Rice's gene pool consists of wild rice (O. rufipogon Griff.), cultivated rice (O. sativaL.) and a weedy form (O. sativa f spontanea). All three components were studied in Thailand to understand evolutionary processes that affect the rice gene pool. Our results indicate that wild rice retains high levels of genetic variation both within and among populations and that variation is structured predominantly by life-history traits e.g., perennial and annual types. In addition, high levels of variation is detected among cultivated varieties with significant differentiation between cultivars, indicating that Thai cultivated rice has a broad genetic base with only 20% reduction of genetic diversity from its wild ancestor. The weedy rice populations reveal varying levels of genetic variation within populations, from nearly as high as wild rice to near zero, to equivalent of modern varieties of cultivated rice. The weedy rice populations are structured by their genetic similarity and differentiation into 2 groups based on their associated cultivated rice varieties, whether the varieties are a modern, high yield or traditional. The spread of invasive weedy rice in Thailand is the result of hybridization and gene flow between native wild rice and local cultivated rice in the areas of co-occurrence in the rice landscape. The predominance of traits associated with outcrossing in the weedy rice, especially an extruded stigma,enables backcrossing to crop rice. This backcrossing in combination with selection pressure due to rice field management has made weedy rice genetically similar to cultivated rice, by the well known process of crop mimicry. The diversity analysis of the rice gene pool in Thailand has established that this is a dynamic genetic system. Gene flow is ongoing among its three main components, first between cultivated and wild rice which results in weedy rice, which in turn crosses with both cultivated and wild rice.

Broader Impacts:

1 - Washington University, Department Of Biology, CAMPUS BOX 1137, 1 Brookings Drive, St. Louis, MO, 63130-4899, USA
2 - Chiang Mai University, Plant Science and Natural Resources, 239 Huay Kaew Rd, Chang Puek, Muang, Chiang Mai, 50200, Thailand

Keywords:
Oryza sativa
Population structure
Oryza rufipogon
Weedy rice
primary gene pool.

Presentation Type: Oral Paper:Papers for Topics
Session: 03
Location: Lindell D/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 10:45 AM
Number: 03012
Abstract ID:131