Fig. 5

Differential expression of unigenes involved in carbon fixation in E8 and E24 compared to C samples of Hevea brasiliensis. The C3 carbon fixation proceeds through 13 steps in three phases. In carboxylation phase, ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCo) adds carbon dioxide to ribulose-1,5-bisphosphate (RuBP) to generate 3-PG (Step 1). Reduction phase include two reactions: PGK catalyses the phosphorylation of 3-PG by ATP to form 1,3-BPG (or 3-phospho-D-glyceroyl phosphate) and ADP (Step 2); GADPH catalyses the reduction of 1,3-BPG by NADPH to produce G3P (Step 3). The regeneration phase of the cycle comprises 9 steps and is initiated by the enzyme TPI which catalyses the interconversion of G3P and DHAP (Step 4). Then fructose-1,6-bisphosphate aldolase (FBA) reversibly catalyses the aldol condensation of G3P and DHAP into fructose-1,6-bisphosphate (Step 5). The resulting fructose-1,6-bisphosphatase is converted into fructose 6-phosphate by fructose-1,6-bisphosphatase (FBP) (Step 6). Transketolase (TK) catalyzes the transfer of a 2-carbon fragment from fructose 6-phosphate to G3P, affording erythrose-4-phosphate and xylulose-5-phosphate (Step 7). Erythrose-4-phosphate and a DHAP are converted into sedoheptulose-1,7-bisphosphate by aldolase (Step 8). The cleavage of sedoheptulose-1,7-bisphosphate into sedoheptulose-7-phosphate and an inorganic phosphate ion is catalyzed by sedoheptulose-1,7-bisphosphatase (SBP) (Step 9). The reversible interconversion of sedoheptulose-7-phosphate and G3P into ribose 5-phosphate and xylulose 5-phosphate is catalyzed by TK (Step 10). Ribose-5-phosphate isomerase (RPI) interconverts ribose-5-phosphate and ribulose-5-phosphate (Step 11). Finally, phosphoribulokinase (PRK) phosphorylates ribulose-5-phosphate into RuBP (Step 12). Cells with gray border lines in the upper rows represent differentially expressed unigenes in E8 compared to C and cells with green border lines in the lower rows represent differentially expressed unigenes in E24 compared to C. Relative levels of expression are showed by a color gradient from low (blue) to high (red)