Salt tolerance of two wheat – Agropyron junceum disomic addition lines

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Abstract
Two wheat-Agropyron junceum disomic addition lines homoeologous to groups and 5 were tested for tolerance to salt. The experiments included germination and growth to maturity at various concentrations of sodium chloride (NaCl). The results were compared with those of wheat lines tetrasomic for chromosomes 2A, 2B, 2D, 5A, 5B, and 5D and also with the wheat parent ''Chinese Spring'', and the salt-tolerant ''Chinese Spring''-A. junceum amphiploid. The addition of homoeologous group 2 chromosomes reduced the tolerance to salt relative to ''Chinese Spring'' in every case. The order of tolerance was ranked as ''Chinese Spring'' > 2J disomic addition line > tetra 2A = tetra 2D > tetra 2B. The addition of wheat group 5 chromosomes was either equal to ''Chinese Spring'' or worse with respect to tolerance to salt. However, the disomic addition line for 5J showed considerable tolerance to salt and at 200 mol m-3 NaCl produced a similar response to that of the amphiploid in producing fertile tillers. Both produced viable grain, but the grain produced by the 5J addition line at 200 mol-3 NaCl was small and shrivelled, unlike the plump grain produced by the amphiploid. The order of tolerance was ranked as amphiploid > 5J addition line > ''Chinese Spring" = tetra 5A > tetra 5B = tetra 5D. It is concluded that there are genes on the group 2 chromosomes that confer susceptibility to salt and that chromosome 5J of A. junceum carries a major gene(s) for tolerance to salt. The potential for transferring this character into wheat is discussed. A hpothesis is also proposed to explain the function of the salt-tolerance gene(s) at critical stages in the life cycle of wheat.