Molecular Ecology and Evolution
Hsu, Shih-Chung , Olsen, Kenneth , Pusadee, Tonapha , Schaal, Barbara .
Global evidence suggests separate crop origins of weedy rice (Oryza sativa L.).
Several hypotheses for the origin of weedy rice, the conspecific weed of cultivated rice (Oryza sativa L.), have been proposed, including derivation from its wild progenitor (O. rufipogon Griff.), introgression between wild and cultivated rice, hybridization between distinct cultivars or de-domestication from the crop. We have used genome-wide sequence tagged site (STS) loci and the pericarp color gene Rc to infer the genetic structure and origin of weedy rice by comparing sequences with both cultivated rice and O. rufipogon. We found for weedy rice from Japan, South Korea, Thailand and Portugal lower sequence polymorphism at STS loci than in cultivated rice. Moreover, there is usually close genetic similarity to locally grown cultivars. Weedy rice that is similar to temperate japonica rice was found in Japan, S. Korea and Portugal, countries which cultivate japonica rice, whereas in Thailand, which cultivates indica rice, the weedy rice is genetically similar to indica cultivars. We also found indica type of weedy rice in S. Korea, which once cultivated indica rice. Interestingly, both temperate japonica and indica types of weedy rice were found in a single field in S. Korea. In contrast, US weedy rice has genetic similarities to indica and aus cultivars that have never been commercially grown in the US. Our results suggest that weedy rice has arisen multiple times across rice growing regions of the world, both within and outside the range of its wild progenitor. At least in some areas, weedy rice may have developed through independent origins from local cultivated rice. The low sequence polymorphisms detected at STS loci imply that either strong selection by weed management practices or founder effects may have shaped the genetic structure of weedy rice. Analysis of Rc gene haplotypes suggests that some weedy rice may have an origin via de-domestication or possibly by parallel evolution of a specific Rc haplotype. We conclude that weedy rice may originate from cultivated rice by diverse mechanisms.
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1 - Washington University, Biology, 1 Brookings Drive, Campus Box 1137, St. Louis, MO, 63130, USA
pericarp gene Rc.
Presentation Type: Oral Paper:Papers for Topics
Location: Westminster Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 1:30 PM