Genetic variation for improving the salt tolerance of durum wheat

Durum wheat (AB genomes) is more salt-sensitive than bread wheat (ABD genomes), 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 genome that results in low Na(+) uptake and enhanced K(+)/Na(+) discrimination. In order to introduce salt tolerance into current durum wheats from sources other than the D genome, a search for genetic variation in salt tolerance was made across a wide range of tetraploids representing 5 Triticum turgidum sub-species (durum, carthlicum, turgidum, turanicum, polonicum). Selections were screened for low Na(+) uptake and enhanced K(+)/Na(+) discrimination. This was assessed in seedlings grown in 150 mM NaCl with supplemental Ca(2+), by measuring 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 improving salt tolerance in durum wheat breeding programs.