Differences in fructose‐2,6‐bisphosphate metabolism between sections of developing barley leaves

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Abstract
In order to study the regulation of carbohydrate metabolism in leaf tissue the activity of fructose‐6‐phosphate,2‐kinase was determined in individual sections of developing primary leaves of barley. Activity was about 25‐fold higher in the leaf tip than in the leaf sheath when measured on a fresh weight basis. There was a gradual increase in enzyme activity from the leaf base to the leaf tip. The higher activity of fructose‐6‐phosphate,2‐kinase in the apical parts of the leaf was associated with higher levels of fructose‐2,6‐bisphosphate. This was especially pronounced when isolated leaf segments were treated with vanadate and kept in darkness. As compared to the kinase, little difference was observed in the fructose‐2,6‐bisphospatase activity among leaf sections. The significance of these patterns for regulation of carbohydrate metabolism in different tissues is discussed.