Photosynthesis and the accumulation of proline in response to water deficit [barley]
1992
Joyce, P.A. | Aspinall, D. | Paleg, L.G. (Waite Agricultural Research Inst., Glen Osmond (Australia). Dept. of Horticulture, Viticulture and Oenology)
Increasing the CO2 content of the air surrounding stressed tissue from excised leaves of barley had no effect on proline accumulation and reducing it to zero reduced proline accumulation only in leaves previously kept in darkness. The direct contribution of assimilated carbon to proline synthesis, assessed with labelled CO2, was small. The potential energy supply from photosynthesis during water stress was more than adequate for proline synthesis, but the potential energy supply from carbohydrate oxidation for segments stressed in darkness became limiting in leaves incubated in darkness for 48 h before stress. Energy provision from current photosynthesis may thus contribute to light stimulation of proline accumulation. Illumination modified the soluble carbohydrate content of the leaf segments and these variations were related to the rates of proline synthesis and oxidation. However, these effects were over-ridden by stress, and the mechanism of the response to light is not fully explained.
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