Nitrogen assimilating enzyme activities and enzyme protein during development and senescence of effective and plant gene-controlled ineffective alfalfa nodules

• Published in: Plant physiology (Bethesda) 1989-11, Vol.91 (3), p.898-904
• Main Authors: Egli, M.A. (University of Minnesota, St. Paul, MN), Griffith, S.M, Miller, S.S, Anderson, M.P, Vance, C.P
• Format: Article
• Language: English
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; activity; Agronomy. Soil science and plant productions; Alfalfa; assimilation; Biological and medical sciences; CONTROL GENETICO; correlation; Defoliation; development; Developmental biology; Economic plant physiology; ENVEJECIMIENTO; ENZIMAS; ENZYME; Enzyme activity; Enzymes; FIJACION DEL NITROGENO; FIXATION DE L'AZOTE; FORMATION DE NODOSITES; Fundamental and applied biological sciences. Psychology; genes; in1 gene; LUTTE GENETIQUE; MEDICAGO SATIVA; METABOLISME DE L'AZOTE; METABOLISMO DEL NITROGENO; nitrogen; NODULACION; Nodules; Parasitism and symbiosis; Plant physiology and development; Plant roots; Plants; RACINE; RAICES; RHIZOBIUM; Root nodules; senescence; Soybeans; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); VIEILLISSEMENT
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.91.3.898

Effective (N2-fixing) alfalfa (Medicago sativa L.) and plant-controlled ineffective (non-N2-fixing) alfalfa recessive for the in1 gene were compared to determine the effects of the in1 gene on nodule development, acetylene reduction activity (ARA), and nodule enzymes associated with N assimilation and disease resistance. Effective nodule ARA reached a maximum before activities of glutamine synthetase (GS), glutamate synthase (GOGAT), aspartate aminotransferase (AAT), asparagine synthetase (AS), and phosphoenolpyruvate carboxylase (PEPC) peaked. Ineffective nodule ARA was only 5% of effective nodule ARA. Developmental profiles of GS, GOGAT, AAT, and PEPC activities were similar for effective and ineffective nodules, but activities in ineffective nodules were lower and declined earlier. Little AS activity was detected in developing ineffective nodules. Changes in GS, GOGAT, AAT, and PEPC activities in developing and senescent effective and ineffective nodules generally paralleled amounts of immunologically detectable enzyme polypeptides. Effective nodule GS, GOGAT, AAT, AS, and PEPC activities declined after defoliation. Activities of glutamate dehydrogenase, malate dehydrogenase, phenylalanine ammonia lyase, and caffeic acid-o-methyltransferase were unrelated to nodule effectiveness. Maximum expression of nodule N-assimilating enzymes appeared to require the continued presence of a product associated with effective bacteroids that was lacking in in1 effective nodules