Research Center for Advanced Analysis, NARO

Development of "spreading phenotype" rice that suppresses the growth of weeds

- Burden of weed control can be reduced by the development of cultivars that utilize the genes of wild rice -

National Agriculture and Food Research Organization (NARO) has developed a "spreading phenotype" rice inbred line that suppresses the growth of weeds while maintaining the quality and yield of rice by utilizing the genes of wild rice. By blocking sunlight more efficiently than conventional cultivars, the spreading phenotype rice suppresses the growth of weeds under the paddy rice canopy to less than half of the original cultivars. This research result reduces the burden of weed control (spraying herbicides and weeding work) in paddy rice cultivation and paves the way for new paddy rice cultivars that are friendly to both farmers and the environment.


NARO has developed a "Spreading phenotype" rice inbred line that suppresses the growth of weeds by introducing the genes for wild rice. The spreading phenotype rice has leaves arranged in a parabolic antenna shape, and by blocking sunlight more efficiently than conventional cultivars, it suppresses the growth of weeds that fall in the paddy rice canopy to less than half. Also, it can receive sunlight more efficiently, which promotes early growth. The spreading leaves stand erect in the latter half of growth, so they can be harvested in the same way as conventional cultivars. The wild rice genes used in this study have almost no effect on yield, grain quality, and taste. Therefore, by utilizing spreading phenotype rice as a breeding material and crossing it with cultivars planted in various parts of Japan, it is expected to cultivate practical paddy rice cultivars with excellent weed control.
The spreading phenotype rice is expected to reduce the production cost by reducing weed control, which is a heavy burden in paddy rice cultivation, specifically, herbicide spraying and manual weed removing work. Also, reducing the amount of herbicide sprayed will lead to the construction of a food production system with a low environmental load, and is expected to contribute to the Measures for achievement of Decarbonization and Resilience with Innovation (MeaDRI) and Sustainable Development Goals (SDGs).
The currently cultivated rice is established from wild rice through a process called "domestication". Domestication was achieved by ancient people who lived about 10,000 years ago by means of selecting lines suitable for the agricultural form at that time. However, on the other hand, in the process of this selection, various diverse genes originally possessed by wild rice have been lost. The genes responsible for the spreading phenotype were found in the process of searching for genes that are also useful in modern agriculture from among the genes lost by domestication.
This research also indicates that useful genes that were not inherited by cultivated rice lie in the genetic resources of wild rice.


N. Inagaki, H. Asami, H. Hirabayashi, A. Uchino, T. Imaizumi, K. Ishimaru (2021) A rice ancestral genetic resource conferring ideal plant shapes for vegetative growth and weed suppression Frontiers in Plant Science 12: 748531(doi: 10.3389/fpls.2021.748531)

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