A team of investigators led by Motoyuki Ashikari of Nagoya University and Hitoshi Sakakibara of the Plant Science Center in Yokohama, Japan, analyzed the rice genome and identified several regions of DNA tied to improved grain yields. They discovered that a gene known as Gn1a controls an enzyme that degrades the hormone cytokinin. Plants with lower levels of Gn1a have more cytokinin available, which leads to better reproductive development and thus more grains. Producing more seeds, however, often makes the plants top-heavy, which in turn makes them susceptible to being blown over. The team counteracted this problem by combining plants carrying favorable Gn1a genes with those that had a gene that favors shorter plant height, which resulted in rice plants with better survival rates.
The new plants provided between 23 and 34 percent more grains per plant than controls did. The researchers note that their genome-scanning approach should work for identifying genes that can improve disease resistance and stress tolerance, among other desired traits. Their results were published online on Thursday by the journal Science.