2 DIFFERENT GLUTAMINE-SYNTHETASE ISOFORMS ARE EXPRESSED IN DEVELOPINGCHICKPEA (CICER-ARIETINUM L.) NODULES

Ontogenetic changes in glutamine synthetase were studied in relation t o dinitrogen fixation in chickpea ( Cicer arietinum L.) nodules. Two G S isoforms (designated as GS(n1) and GS(n2)) were observed during acti ve stages of nitrogen fixation whereas mainly one GS isoform (GS(n2)) was observed in the degenerating nodules. There was a substantial incr ease in the activity of GS(n1) during active nitrogen fixation, sugges ting that GS(n1) plays an important role in ammonia assimilation in ch ickpea nodules. In contrast to other legume nodules, electrophoretic m obility of GSn(1) in chickpea nodules was faster than that of GS(n2). These observations suggest that GS(n1) appears to be quite different t han the GS(n1) reported in the ocher legume nodules.