The rôle of reducing sugars in the geotropic response of the wheat node.

The distribution of sugars in the leaf sheath base of wheat (Triticum aestivum) becomes asymmetric following horizontal displacement, the reducing sugar content of the lower side rising to 300-400% of that of the upper side during a 24-h stimulation period. The changes involve the hydrolysis of sucrose and appear, in older organs, in the absence of growth. Although gravity-induced, the increase in reducing sugar content is not essential for initiation of the growth which gives rise to the geotropic response.