Research Express@NCKU - Articles Digest
Research Express@NCKU Volume 22 Issue 8 - July 20, 2012 [ http://research.ncku.edu.tw/re/articles/e/20120720/3.html ]
Phylogeography of Asian wild rice, Oryza rufipogon,
reveals multiple independent domestications of
cultivated rice, Oryza sativa
Tzen-Yuh Chiang
*, J. P. Londo, Y. C. Chiang, K. H. Hung, B. A. Schaal
Department of Life Sciences, Instituite of Biological Sciences and Technology, National Cheng Kung University
[email protected] PNAS 103: 9578–9583. 2006
R
ice (Oryza sativa L.) is one of the staple crops for human’s life, feeding more than half of the human population. Like many other crops, the domestication of rice from the wild progenitor, O. rufipogon, 8,000 to 10,000 years before present according to the archeological evidence, represents one of the most important events of human history, allowing human ancestors access to great food resources. Two major subspecies, indica and japonica, of rice have been developed via selections of characteristics, such as stickiness of rice grains, reducing shattering, grain discoloration, and so on.Nevertheless, the history of cultivated rice’s domestication from its wild ancestor remains unclear. The
phylogeographical analysis based on the genetic variation enables us to reconstruct the domestication history of crops. Results indicate that India and Indochina of South Asia may represent the ancestral center of diversity for the wild rice. Besides, cultivated rice was domesticated at least twice from wild rice populations. The products of the two independent domestication events are indica and japonica. Phylogeographical analyses revealed that indica was domesticated within a region of eastern India, Myanmar, and Thailand, whereas japonica was domesticated from wild rice in southern China.
Based on these results, we have been working on the artifical selection of genes of the photoperiod pathway.
Geographiclaly, ssp. indica is distributed throughout subtropical and tropical Asia, whereas ssp. japonica mainly grows in the temperate regions, displaying latitudinal differentiation. We examined the genetic diversity and apportionment patterns of alleles at three major genes of the photoperiod pathway, including Phytochrome B, Hd1, and Hd3a genes. PhytB gene and other background genes displayed low genetic variation, while Hd1 and Hd3a genes were highly polymorphic within cultivated rice. Genetic analyses showing high linkage disequilibrium between Hd1 and Hd3a gene shed lights on the footprints of the rice domestication.
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Research Express@NCKU - Articles Digest
Diversifying selection on the Hd1 gene of the photoperiod pathway
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