Influence of Proline and Glycinebetaine on Salt Tolerance of Cultured Barley Embryos

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Abstract
Lone, M. I., Kueh, J. S. H., Wyn Jones, R. G. and Bright, S. W. J. 1987. Influence of proline and glycinebetaine on salt tolerance of cultured barley embryos.—J. exp. Bot. 38: 479–490. The addition of exogenous proline and glycinebetaine to cultured barley (Hordeum vulgare L. cv. Maris Mink) embryos increased shoot elongation under saline conditions. Inhibition of shoot elongation by NaCl was relieved by proline when plantlets were grown in deep crystallizing dishes but not in Petri dishes where shoots come into direct contact with the medium. The effect of proline could be related to a decrease in shoot Cl– and Na+ accumulation which was only observed in plantlets grown in crystallizing dishes. Proline but not betaine uptake into cultured plantlets was stimulated by NaCl while each organic solute inhibited the endogenous synthesis of the other solute under salt stress. Comparison of the effects of exogenously supplied proline with enhanced endogenous proline accumulation in the mutant line R5201 suggested that the increased proline accumulation in the mutant is an order of magnitude too low to have a significant physiological effect. The implications of the effect of proline on ion transport, discrimination and accumulation are discussed.