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Nodule physiology of a supernodulating pea mutant
Author(s) -
Rosendahl Lis,
Vance Carroll P.,
Miller Susan S.,
Jacobsen Evert
Publication year - 1989
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1989.tb05398.x
Subject(s) - nitrogenase , pisum , biology , nod , sativum , symbiosis , nitrogen fixation , nodule (geology) , botany , glutamine synthetase , biochemistry , glutamine , bacteria , paleontology , amino acid , gene , genetics
Physiological and biochemical parameters of the supernodulating pea ( Pisum sativum L.) mutant nod 3 were compared to those of its wild‐type parent cv. Rondo in a nil nitrate environment. Plants of cv. Rondo produced more biomass and accumulated more N than plants of nod 3 . Accordingly, seed yield of the wild type was twice that of the supernodulating mutant. Although the nodule number of nod 3 was 10‐fold that of cv. Rondo, the nodule mass of nod 3 was only twice that of cv. Rondo as individual nodules were smaller in nod 3 than in cv. Rondo. The maximum rate of acetylene reduction activity, determined in an open flow‐through gas system, was higher in the wild type than in nod 3 when expressed on a nodule dry weight basis. However, when expressed on a whole plant basis, the nitrogenase activity (acetylene reduction) was similar in the two symbioses. The net carbon costs of nitrogenase activity was 25% lower in nod 3 than in cv. Rondo. An equal proportion of the net CO 2 efflux from the root system was for growth and maintenance of the tissue in the two symbioses. However, growth and maintenance respiration was higher in nod 3 than in cv. Rondo per gram dry weight of the nodulated root system. The nodules of nod 3 had a reduced soluble protein concentration as compared to those of the wild type. The specific activities of nodule glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 1.4.1.14) and asparagine synthetase (EC 6.3.5.4) were lower in nod 3 than in cv. Rondo. The root bleeding sap of nod 3 contained lower amounts of glutamine and higher amounts of asparagine than that of cv. Rondo. The results suggest that the use of carbon directly related to the dinitrogen fixation and nitrogen assimilation may be less in nod 3 than in cv. Rondo, and that there may be differences between the two symbioses in the pathway for assimilation of fixed nitrogen.