Enhanced osmotolerance of a wheat mutant selected for potassium accumulation.

A mutant of durum wheat was identified by screening a M4 population (sodium azide) for genotypes with enhanced capacity for potassium accumulation in leaves. The mutant (designated 422) was grown in field, controlled environment, hydroponic culture and NaCl salinized soil. Mutant 422 accumulates about 5 mg/g dry weight more K than the wild-type and is less salt sensitive, based on leaf growth and germination. During vegetative growth exists a specific tolerance of the 422 mutant to K(+) ion and a moderate tolerance to Cl(-) ion, in hydroponic culture. Under severe stress imposed by salts and mannitol, the mutant germinates better than wild type (WT). In soil containing increasing NaCl, mutant 422 had higher potassium amount than WT, but did not show augmented capacity to concentrate the ion in the leaves as salt stress increased. The capability to accumulate potassium could improve tissue hydration, because water content of 422 leaves was greater than WT and increased linearly in relation to leaf K(+) concentration.