Research Team Discovers Genetic Mutations that Made Rice Cultivation Possible

A study conducted by an international research collaboration suggests that the emergence of cultivated rice from wild rice plants is the result of three gene mutations 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.

For more details, read the article in Research at Kobe.