Soil salinization poses a serious threat to global rice production. At present, the natural‑variation‑based genetic basis of rice salt tolerance remains poorly understood, and only a handful of major genes related to salt tolerance have been functionally characterized. It is critical to identify key gene modules in salt signaling pathways.

In a study published in Developmental Cell on August 28, a team led by Prof. CHONG Kang from the Institute of Botany of the Chinese Academy of Sciences identified a major quantitative trait locus (QTL) gene designated Tolerance to Salt 1 (TOLS1), and revealed how it shapes rice salt tolerance, providing new genetic resources and insights for breeding salt-tolerant rice varieties.

A genome-wide association study was conducted on 242 diverse rice accessions. Through map-based cloning, researchers identified a major QTL, TOLS1, which acts as a negative regulator of salt tolerance by physically interacting with the small GTPase OsRacB and enhancing its GTPase activity. This process weakens salt-induced cytosolic Ca²⁺ signaling and thus reduces salt tolerance.

Moreover, researchers revealed that a natural coding variant (SNP9) in TOLS1 contributes to functional divergence among cultivars. Notably, they found that genome editing of TOLS1 improves salt tolerance without obvious negative effects on key agronomic traits, highlighting its potential for precision breeding.

These findings show that TOLS1 may serve as a "molecular brake" that constrains OsRacB-mediated Ca²⁺ signaling within the salt-response network. Targeted modification of such brake components represents a viable strategy for breeding rice varieties with balanced stress resilience and grain yield performance.

Rice paddy field at Xiangshan Breeding Base, Institute of Botany. (Image by Dr. LUO Wei)