ENHANCEMENT OF THE SALT TOLERANCE OF TRITICUM-TURGIDUM L BY THE KNA1 LOCUS TRANSFERRED FROM THE TRITICUM-AESTIVUM L CHROMOSOME 4D BY HOMOEOLOGOUS RECOMBINATION

Durum wheat, Triticum turgidum L. (2n = 4x = 28, genome formula AABB) is inferior to bread wheat, T. aestivum L. (2n = 6x = 42, genome formu la AABBDD), in the ability to exclude Na+ under salt strees, in the ra tio of the accumulated K+ to Na+ in the leaves under salt stress, and in tolerance of salt stress. Previous work showed that chromosome 4D h as a major effect on Na+ and K+ accumulation in the leaves of bread wh eat. The 4D chromosome was recombined with chromosome 4B in the geneti c background of durum wheat. The recombinants showed that Na+ exclusio n and enhanced K+/Na+ ratio in the shoots were controlled by a single locus, Kna1, in the long arm of chromosome 4D. The recombinant familie s were grown in the field under non-saline conditions and two levels o f salinity to determine whether Kna1 confers salt tolerance. Under sal t stress, the Kna1 families had higher K-/+Na+ ratios in the flag leav es and higher yields of grain and biomass than the Kna1 families and t he parental cultivars. Kna1 is, therefore, one of the factors responsi ble for the higher salt tolerance of bread wheat relative to durum whe at. The present work provides conceptual evidence that tolerance of sa lt stress can be transferred between species in the tribe Triticeae.