Cultivated rice (Oryza sativa L.) was domesticated from the Asian wild species, Oryza rufipogon Griff. Among morphological differences between them, one of the striking traits specific to cultivated rice is loss of seed shattering. In the early stage of rice domestication, the related traits of this character have been desirable for the ancient seed gatherers because it enhances the efficiency of seed collection. In this chapter, we propose that three morphological traits, closed panicle shape, non-seed shattering, and seed awning, played important roles in controlling the degree of seed dispersal. First, we reviewed domestication loci controlling the three traits. We then evaluated allele effects at these loci using reciprocal backcross populations between O. sativa Nipponbare and our standard wild accession of O. rufipogon W630. In the genetic background of cultivated rice, all the wild functional alleles were responsible for these domestication traits. On the other hand, cultivated non-functional alleles were not always associated with the drastic morphological changes in the genetic background of wild rice. Since ancient humans have selected cultivated-type mutants in natural wild populations, possible domestication process for the emergence of cultivated rice is discussed based on the effects of cultivated non-functional alleles.
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We thank Dr. Cristina Castillo, University College London, UK, for her critical reading and editing of the manuscript. The seeds of wild rice accession, O. rufipogon W630, were kindly provided by the National Institute of Genetics (National Bioresource Project), Japan. This work was supported in part by a Grant-in-Aid from Japanese Society for Promotion of Science (nos. 26292004 and 26450003).
Bessho-Uehara K, Wang DR, Furuta T et al (2016) Loss of function at RAE2, a previously unidentified EPFL, is required for awnlessness in cultivated Asian rice. Proc Natl Acad Sci USA 113:8969–8974CrossRefPubMedPubMedCentralGoogle Scholar
Eiguchi M, Sano Y (1990) A gene complex responsible for seed shattering and panicle spreading found in common wild rices. Rice Genet Newslett 7:105–107Google Scholar
Ikemoto M, Otsuka M, Thanh PT et al (2017) Gene interaction at seed-awning loci in the genetic background of wild rice. Genes Genet Syst 92:1–6CrossRefGoogle Scholar
Ishii T, Numaguchi K, Miura K et al (2013) OsLG1 regulates a closed panicle trait in domesticated rice. Nat Genet 45:462–465CrossRefPubMedGoogle Scholar
Ishikawa R, Thanh PT, Nimura N et al (2010) Allelic interaction at seed-shattering loci in the genetic backgrounds of wild and cultivated rice species. Genes Genet Syst 85:265–271CrossRefPubMedGoogle Scholar
Jin J, Hua L, Zhu Z et al (2016) GAD1 encodes a secreted peptide that regulates grain number, grain length and awn development in rice domestication. Plant Cell 28:2453–2463CrossRefPubMedPubMedCentralGoogle Scholar
Konishi S, Izawa T, Lin SY et al (2006) An SNP caused loss of seed shattering during rice domestication. Science 312:1392–1396CrossRefPubMedGoogle Scholar
Lee J, Park JJ, Kim SL et al (2007) Mutations in the rice liguleless gene result in a complete loss of the auricle, ligule, and laminar joint. Plant Mol Biol 65:487–499CrossRefPubMedGoogle Scholar
Luo J, Liu H, Zhou T et al (2013) An-1 encodes a basic helix-loop-helix protein that regulates awn development, grain size, and grain number in rice. Plant Cell 25:3360–3376CrossRefPubMedPubMedCentralGoogle Scholar
Oka HI (1988) Origin of cultivated rice. Elsevier, AmsterdamGoogle Scholar
Onishi K, Takagi K, Kontani M et al (2007) Different patterns of genealogical relationships found in the two major QTLs causing reduction of seed shattering during rice domestication. Genome 50:757–766CrossRefPubMedGoogle Scholar
Yang Z, Wang X, Gu S et al (2008) Comparative study of SBP-box gene family in Arabidopsis and rice. Gene 407:1–11CrossRefPubMedGoogle Scholar
Zhang LB, Zhu Q, Wu ZQ et al (2009) Selection on grain shattering genes and rates of rice domestication. New Phytol 184:708–720CrossRefPubMedGoogle Scholar