Gene dosage at the amylose-extender locus of maize: Effects on the levels of starch branching enzymes

Soluble starch branching enzymes and starch synthases from maize kernels of differing dosage of the ae locus were purified by DEAE-cellulose chromatography. A near-linear relationship between increasing dosage of the dominate amylose-extender allele (Ae) and branching enzyme IIb activity was found. In contrast, levels and properties of branching enzymes I and IIa, as well as the citrate-stimulated and primer-requiring starch synthases, remained unchanged. The near-linear increase in branching enzyme IIb activity with increasing doses of the Ae allele is consistent with the hypothesis that ae is the structural gene coding for branching enzyme IIb.Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers University, New Brunswick. This work was performed as part of NJAES Projects 12442 and 12201 (NE-124), supported by the New Jersey Agricultural Experiment Station, Regional Research Funds, NSF Grant PCM 78-16127, and funds from Corn Refiners Association, Inc.