ONTOGENIC CHANGES IN PHOTOSYNTHETIC CARBON-REDUCTION CYCLE METABOLITES AND ENZYMES OF SUCROSE METABOLISM IN BRASSICA-CAMPESTRIS PODS

Rate of net CO2 exchange (P(N)), changes in the activities of the key enzymes of sucrose and fructose-2,6-bisphosphate (F-2,6-P2) synthesis and levels of certain metabolites of the photosynthetic carbon reduction (PCR) cycle were determined in pod wall of Brassica at different stages of pod development. P(N), activities of sucrose-P-synthetase (SPS) and fructose-1,6-bisphosphatase (FBPase) and the contents of 3-phosphoglycerate (3-PGA), ribulose-1,5-bisphosphate (RuBP), glyceraldehyde-3-phosphate (Gly-3-P), dihydroxyacetone phosphate (DHAP) and uridine diphosphoglucose (UDPG) increased upto 21 d after anthesis followed by a continuous decrease until maturity. However, the content of fructose-6-phosphate (F-6-P) started decreasing only after 28 d of anthesis. Changes in F-2,6-P2 content were closely associated with the changes in F-6-P-2-kinase activity rather than with F-2,6-P2ase activity.