Summary
Chlorella pyrenoidosa was subjected to low water potentials and the resulting changes in carbohydrate metabolism were measured.
Water deficit reduced the incorporation of 14C-glucose into methanol insoluble compounds, principally starch and increased that into sucrose. Even moderate water deficit, for example potentials of -2.5 and -5 atm, greatly reduced the incorporation of 14C-glucose into uridine diphosphate glucose, while 14C levels of the hexose monophosphates changed little, indicating a direct stimulus of sucrose synthesis. This increased sucrose synthesis was one of the earliest effect of water deficit, because potentials of -2.5 and -5 atm did not reduce respiration and glucose uptake.
At lower water potentials (-10 atm or less) there was reduced 14C incorporation into all sugar phosphates. This resulted from a combination of reduced 14C-glucose uptake and increased sucrose synthesis.
Water potentials as low as -20 atm had little effect on acetate uptake, or on the 14C levels in the intermediates of the TCA cycle. This confirmed that low water potentials do not directly inhibit respiratory pathways in Chlorella.
The results are discussed in relation to the effect of water deficit on levels of various metabolites in vascular plants, which have been reported by other workers.
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Hiller, R.G., Greenway, H. Effects of low water potentials on some aspects of carbohydrate metabolism in Chlorella pyrenoidosa . Planta 78, 49–59 (1967). https://doi.org/10.1007/BF00384857
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DOI: https://doi.org/10.1007/BF00384857