A study conducted by an international research collaboration suggests
that the emergence of cultivatedrice from wild rice plants is the result
of threegenemutations that make the seeds fall from the plant less
easily. The researchers discovered that each of the three mutations
individually has little effect, but when all three mutations are
present, rice panicles retain more of their seeds, resulting in a
greater crop yield.

The researchers discovered that the causal mutation in the/qSH3/gene is
necessary to prevent rice seeds from falling (called seed shattering).
In the/qSH3/gene mutation, a single nucleotide substitution on the gene
(YABBY) is found in the majority of indica and japonica cultivars, the
world's most widely farmed rice species. This research found that plants
with only the/qSH3/gene mutation dropped their seeds naturally. When
the/qSH3/mutation was combined with the previously reported/sh4/gene
mutation, the abscission layer required for seed shattering was
partially inhibited.

An analysis of structural mechanics was performed to determine the
relationship between panicle opening and closing and inhibition of the
abscission layer. The results showed that when all three mutations are
present, shattering was suppressed and the seeds remained attached to
the panicles. It is believed that man's hunter-gatherer ancestors
observed the visual characteristics of certain rice plants with a higher
yield and began cultivating them, paving the way for rice to become a
staple crop.

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