Salt stress is a major constraint across large rice-producing areas because of the high sensitivity of modern rice varieties. Tolerance for salinity is complex, involving a number of different physiological mechanisms, including sodium exclusion from roots, controlled sodium transport between roots and shoots, and sequestering of sodium in older tissues and in the vacuoles. Although many genes likely contribute to salt tolerance, a major quantitative trait locus (QTL) of surprisingly large effect has been identified from the salt-tolerant landrace 'Pokkali'. We are currently fine-mapping the Saltol QTL, integrating gene expression data with candidate gene analysis, and developing a marker-assisted backcrossing system to transfer the Pokkali Saltol allele into popular varieties. A long-term goal is to identify and combine QTLs/genes controlling different physiological mechanisms to achieve a higher level of salt tolerance in popular rice varieties for a wide range of coastal and inland salt-affected areas.
Presented at the 2006 GCP Annual Research Meeting, 12-16 September 2006, Sao Paolo, Brazil. 1 p.