Photosynthesis and fructose 2,6-bisphosphate content in water stressed wheat leaves

Net photosynthetic rates, sucrose levels, fructose 2,6-biphosphate content and the related enzyme activities were investigated in control and water st ressed leaves of Triticum aestivum L. var sonalica. Fructose 2,6-bisphospha te accumulated in water stressed plants and reduced leaf photosynthesis, su crose content and the activities of fructose 1,6-bisphosphatase and sucrose phosphate synthase. C-14-distribution into starch was more with increasing water stress while C-incorporation into sucrose was drastically reduced in stressed plants. Fructose-6-phosphate-2-kinase activity was extremely high in stressed plants while the activity of fructose 2,6-bisphosphatase was l ow. The results provide a clear evidence that low leaf water potentials res ult in fructose-2,6-bisphosphate accumulation, which modulates photosynthet ic sucrose formation and carbon partitioning in wheat leaves.