NADP(+) glyceraldehyde-3-phosphate dehydrogenase in soybeans [Glycine max (L.) Merr.]: genetics and developmental expression.

Chloroplastic (NADP(+)) glyceraldehyde-3-phosphate dehydrogenase (E.C. 1.2.1.9) catalyzes the second reaction in photosynthesis after the fixation of carbon by RuBisCO. Chloroplast-bound (NADP(+)) G3PDH was resolved in soybean by starch gel electrophoresis using L-histidine-citrate buffer (pH 5.7). Histochemical staining revealed zymogram patterns indicative of a tetramer. A survey of soybean genotypes revealed differences in zymogram patterns between the principal cytoplasmic sources of the northern and southern US germplasms. In the soybean pedigree, an allelic frequency shift toward a five-banded pattern was observed. G3PDH polymorphism was due to allele associated with gene expression at the slow locus. No linkage was found between the slow locus of (NADP(+)) G3PDH and AC02, AC03, AC04, ACP, DIA1, IDH1, IDH2, PGM1, and PGM3. Developmental expression in the above-ground tissues was identical, whereas roots as a rule did not express (NADP(+)) G3PDH activity. The importance of chloroplast-bound (NADP(+)) G3PDH in photo-synthesis and its interesting mode of inheritance warrants further exploration of this enzyme in soybean.