The potential of cell cultures for the production of salt tolerant cultivars.

The progress towards the production of salt tolerant plants through selection in cell cultures is briefly reviewed. The need for a fuller understanding of the mechanisms of salt tolerance in non-halophytes is emphasised and illustrated with reference to recent investigations on the role of proline. A clear protective effect, against salt stress, of exogenously applied proline has been demonstrated suggesting elevated levels of endogenous proline synthesis, for which there is a direct selection procedure, as a basis for improved salt tolerance. Salt tolerance of proline-overproducing plants and cell cultures is currently under investigation in a Nicotiana sylvestris line with almost 100-fold increase in free proline