Root Growth and Carbohydrate Metabolism at Low Temperatures

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Abstract
A study of carbohydrate metabolism in the roots of pea and maize shows that the differing ability of these two species to grow at low temperatures is associated with the maintenance of adequate sugar supplies to the root tip. In the maize root reducing the ambient temperature to 2 °C causes a sharp and continuing fall in the soluble sugar content of the growing tip. A similar treatment with pea roots causes only a temporary reduction in sugar content lasting no more than 24 h. The fall in root sugars in maize is accompanied by a reduction in respiration rate and the cessation of growth. During the periods of sugar shortage caused by low temperatures both respiration and growth can be stimulated in root tips by a supply of exogenous glucose. Pea roots also show an additional ability to adapt to low temperatures by lowering the Km value for invertase after pretreatment at a low temperature. This effect is not seen in maize.