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 ACO2, ACO3, ACO4, 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.