Some agricultural experts believe worldwide crop yields need to double by 2050 to avert a global food crisis. And improving yields of rice is deemed particularly important because rice is the staple food for nearly half of the world’s population. Two groups working independently have now identified a variant of a gene in rice plants that could boost rice yields by 10%, though they must still demonstrate that their experimental breakthrough will pay off in farmers' fields.
The groups were both looking for genes that affect rice yield by comparing different varieties of rice. Jiayang Li of the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences in Beijing and his colleagues worked with one rice variety that produces few stems, or tillers, and another that produces many. Rice plants with fewer tillers tend to have higher yields. A group led by Motoyuki Ashikari of Nagoya University in Japan used two rice varieties with greatly differing numbers of grains in the main panicle, the tip of the tiller where the rice grains form.
Both groups cross-bred their two varieties to produce thousands of plants. Then by comparing genomes of these progeny using numbers of tillers and grains as indicators of likely yield, they zeroed in on a gene named OsSPL14. They separately found that a minor variant, or allele, of OsSPL14, was present in crossbred plants with few tillers and more grains. Ashikari's group found that adding this allele to a low-yield rice variety increased the number of grains produced by 40%. (Increasing the number of grains is not equivalent to increasing yield, which is measured by weight.) Li and his colleagues went a step further with a small field trial in which plants with this allele produced over 10% more rice by weight than those with the more common variant of OsSPL14. Ashikari says he and his colleagues were unaware of Li's work until they had completed their experiments. After the groups confirmed they had found the same gene, they agreed to submit their papers simultaneously. Their separate reports appear online today in Nature Genetics.
"These are elegant studies that bring clarity to the genetic control of one yield component," says Hei Leung, a rice geneticist at the International Rice Research Institute in Los Banos, Philippines. Masahiro Yano, a rice geneticist at Japan's National Institute of Agrobiological Sciences in Tsukuba, agrees that spotting the gene is significant. But he cautions that more research is needed to determine the effectiveness of using this allele in the wide range of cultivated varieties of rice and in different growing environments. Ashikari says his group is working to introduce the OsSPL14 allele and a previously identified gene that also boosts yield into commonly grown varieties. He hopes these will reach farmers within 5 years.