Salt stress is a major constraint across many rice producing areas because of the high sensitivity of modern rice varieties. Tolerance to salinity is complex, involving a number of different physiological mechanisms, such as sodium exclusion from roots, controlled sodium transport between root and shoot, and sequestering of sodium in older tissues and in the vacuoles. Previously, 80 RILs from a cross between IR29 and the landrace Pokkali were used to map several salt tolerance QTLs, including Saltol, a major QTL on the short arm of chromosome 1. Fine mapping of the Saltol QTL is in progress and indel markers based on candidate genes in this region have been developed. A precision marker-assisted backcrossing system is also being employed to efficiently transfer the Pokkali Saltol QTL into popular varieties such as IR64, BR28, and Swarna. The long term goal is to identify and combine genes and QTLs controlling different physiological mechanisms to achieve a higher level of salt tolerance in high yielding rice varieties.
Thomson, M.J.; de Ocampo, M.; Egdane, J.; Katimbang, M.; Rahman, M.A.; Singh, R.K.; Gregorio, G.; Ismail, A.M. QTL mapping and marker-assisted backcrossing for improved salinity tolerance in rice. Presented at the International Plant and Animal Genome Conference, 13-17 January 2007, San Diego, CA, USA. (2007) 1 pp.