Catalyzes the oxidative decarboxylation of 6-phosphogluconate to ribulose 5-phosphate and CO(2), with concomitant reduction of NADP to NADPH (PubMed:26941195). Required for guided growth of the male gametophytes and interaction between the pollen tube and the ovule (PubMed:26941195). 6-phospho-D-gluconate + NADP(+) = CO2 + D-ribulose 5-phosphate + NADPH Carbohydrate degradation; pentose phosphate pathway; D-ribulose 5-phosphate from D-glucose 6-phosphate (oxidative stage): step 3/3. Forms homodimer (PubMed:26941195, PubMed:27366940). Forms heterodimers with PGD1 or PGD3 (PubMed:27366940). Embryonic lethality when homozygous (PubMed:26941195). Defects in pollen tube growth (PubMed:26941195). Belongs to the 6-phosphogluconate dehydrogenase family.