| Abstract |
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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