Inhibition of germination by glucose analogues that are hexokinase substrates

K-is values for the 6-phosphates of D-mannose and 2-deoxy-D-glucose with a plant hexokinase against ATP were high (52 and 62 mM) and there was negligible inhibition against D-glucose. The degree of reduction of germination and seedling growth of fenugreek, mung beans, white mustard and wheat seeds was related to the phosphorylation coefficient and concentration of the added analogue, and varied with plant species. The significance of these results in inhibition is discussed. 2,5-Anhydro-D-mannitol and D-psicose were exceptions. The bisphosphate of the former potently inhibits fructose bisphosphatase and the latter is-a substrate for fructo-6-kinase, consistent with a role for fructo-6-kinase in plants independent of hexokinase. (C) 1998 Elsevier Science Ltd. All rights reserved.