Institute of Agrobiological Sciences, NARO

A mechanism regulating rice root thickness under the mild drought condition

- Toward development of drought-resistant rice cultivars -

The National Agricultural Food Research Organization (NARO) scientists have collected phenomes and transcriptomes of 61 rice accessions with highly diverse below-ground traits grown in an upland field. NARO team discovered genes negatively associated with root growth under the mild drought condition. The study could lead to development of drought-resistant rice cultivars and provides insights on the genomic and transcriptomic basis of phenotypic variation under upland field conditions.


Rice is one of the major cereal crops and produced 800 million tons annually worldwide. Sixty-two percent of rice harvested area (approximately 100 million hectares) have been experienced the yield loss due to drought in these 26 years. reduction is a major food security issue in 62% of rice-producing areas worldwide. Breeding drought-resistant rice varieties is crucial for sustainable food production.
Root system architecture affects plant drought resistance. Drought-resistant field crops tend to have thick and deep roots. The NARO team has previously discovered the DEEPER ROOTING1 gene involved in root growth angle and developed drought-resistant rice cultivars that can gather water from deep soil layers. However, genes involved in root thickness that can be used for cultivar improvement have not been discovered.
The researchers profiled the phenotypic and transcriptomic landscape of 61 rice accessions with highly diverse below-ground traits grown in an upland field. Upland field condition could be considered a mild drought stress treatment for rice compared to paddy field conditions. Root growth was negatively correlated with auxin-inducible genes, suggesting an association between auxin signaling and upland field conditions. A negative correlation between root thickness and stress response-related genes suggested that thicker root is associated with resistance to mild drought stress. The researchers also found phytohormone signaling networks and key transcription factors negatively regulating root thickness. The researchers hope that manipulating these genes would prevent drought-induced root thinning and help developing drought-resistant cultivars in the future.

Relevant information

Budget: Japan Science and Technology Agency CREST (JPMJCR17O1), Japan Society for the Promotion of Science KAKENHI (17H03753).

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Published paper

Kawakatsu T, Teramoto S, Takayasu S, Maruyama N, Nishijima R, Kitomi Y, Uga Y. (2021) The transcriptomic landscapes of rice cultivars with diverse root system architectures grown in upland field conditions. The Plant Journal