Genetic variation for improving the salt tolerance of durum wheat

Durum wheat (AB genomes) is more salt-sensitive than bread wheat (ABD genom es), a feature that restricts its expansion into areas with sodic or saline soils. Salt tolerance in bread wheat is linked with a locus on the D genom e that results in low Na+ uptake and enhanced K+/Na+ discrimination. In ord er to introduce salt tolerance into current durum wheats from sources other than the D genome, a search for genetic variation in salt tolerance was ma de across a wide range of tetraploids representing 5 Triticum turgidum sub- species (durum, carthlicum, turgidum, turanicum, polonicum). Selections wer e screened for low Na+ uptake and enhanced K+/Na+ discrimination. This was assessed in seedlings grown in 150 mM NaCl with supplemental Ca2+, by measu ring the Na+ and K+ accumulated in the blade of a given leaf over 10 days. Large and repeatable genetic variation was found. Low Na+ accumulation and high K+/Na+ discrimination of similar magnitude to that of bread wheat was found in the subspecies durum. These selections have the potential for impr oving salt tolerance in durum wheat breeding programs.