QTL mapping in an interspecific sorghum population uncovers candidate regulators of salinity tolerance

Salt stress impedes plant growth and disrupts normal metabolic processes, resulting in decreased biomass and increased leaf senescence. Therefore, the ability of a plant to maintain biomass when exposed to salinity stress is critical for the production of salt tolerant crops. To identify the genetic basis of salt tolerance in an agronomically important grain crop, we used a recombinant inbred line (RIL) population derived from an interspecific cross between domesticated Sorghum bicolor (inbred Tx7000) and a wild relative, Sorghum propinquum, which have been shown to differ in response to salt exposure. One-hundred seventy-seven F3:5 RILs were exposed to either a control or salt treatment and seven traits related to plant growth and overall health were assessed. A high-density genetic map that covers the 10 Sorghum chromosomes with 1991 markers was used to identify nineteen total QTL related to these traits, ten of which were specific to the salt stress response. Salt-responsive QTL contain numerous genes that have been previously shown to play a role in ionic tolerance, tissue tolerance, and osmotic tolerance, including a large number of aquaporins.