Multiple forms of glutamine synthetase in nodules of tropical legumes inoculated with Bradyrhizobium SPP. and Rhizobium fredii

Abstract

The profiles of glutamine synthetase (GS) activity in the plant fraction of nodule extracts from tropical legumes, inoculated with either fast- or slow-growing rhizobia, were analyzed by non-denaturing polyacrylamide gel electrophoresis. The electrophoretic mobility of nodule GS was plant-dependent but was virtually unaffected by the type of Rhizobium present in the nodules. Only Macroptilium atropurpureum (DC.) Urb. nodule extracts displayed two distinct GS activity bands similar in electrophoretic mobility to those previously reported in Phaseolus vulgaris L. nodules. Nodule extracts of Vigna unguiculata (L.) Walp. exhibited one major and one minor band of GS activity. In contrast, nodule extracts of Glycine max (L.) Merr. and Sesbaniaa rostrata Brem displayed a single zone of GS activity. These experiments indicate that multiple GS activity bands in root nodules are not restricted to P. vulgaris and P. lunatus L. but are probably of widespread occurrence in legumes.