The origins of rice have been cast in a new light by research publishing in the open-access journal PLoS Genetics on June 9, 2011. By reconciling two theories, the authors show that the domestication of rice occurred at least twice independently but with extensive "borrowing" between the two subspecies.
Indica and japonica are, respectively, the southern and northern varieties of rice and they are major staple crops in Asia. Whether they share a single origin of domestication or were domesticated independently twice interests both historians and biologists, and the two views had seemed mutually exclusive. However, researchers from Sun Yat-Sen University and Beijing Institute of Genomics (BIG) and the University of Chicago, are now suggesting that these two views may both be correct, depending on the traits or genes being discussed.
Using new-generation sequencing technology, Suhua Shi, Chung-I Wu, and their research teams studied the kinship of rice by examining the 50,000 or so genes in the rice genome. For most of the genes, indica and japonica are indeed no closer to each other in kinship than each is to wild rice, supporting the more popular view that the two cultivars were independently domesticated. However, when the gene regions for traits influenced by artificial selection were examined, indica and japonica appear to share a surprisingly strong kinship.
In light of this new data, the story of rice domestication may need to be revisited. Early northern and southern farmers may have cultivated rice independently but it seems that they also borrowed desired traits extensively from rice farmed by others, resulting in the opposing kinships reported. This begs the question as to whether intellectual piracy has been with us since humans first became engaged in agricultural production.
FINANCIAL DISCLOSURE: This study is supported by grants from National Basic Research Program of China (2007CB815701), National Natural Science Foundation of China (30730008, 40976081, 31000957, 31071914 and 30970208), National S&T Major Project of China (2009ZX08010-017B, 2009ZX08009-149B), Yat-Sen innovation project (SYSU), Beijing Institute of Genomics, SRF for ROCS, and Chinese Academy of Sciences (KSCX1-YW-22). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
COMPETING INTERESTS: The authors have declared that no competing interests exist.
CITATION: He Z, Zhai W, Wen H, Tang T, Wang Y, et al. (2011) Two Evolutionary Histories in the Genome of Rice: the Roles of Domestication Genes. PLoS Genet 7(6): e1002100. doi:10.1371/journal.pgen.1002100
Prof. Chung-I Wu
Beijing Institute of Genomics, Chinese Academy of Sciences
Mobile phone : (86) 135 8195 0132
Department of Ecology and Evolution
University of Chicago
Chicago, Illinois, United States of America
Telephone: 773 702 2565 or
Mobile: 773 612 5620
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