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Genetic factors in Rhizobium affecting the symbiotic carbon costs of N 2 fixation and host plant biomass production
Author(s) -
SKØT L.,
Hirsch P. R.,
Witty J. F.
Publication year - 1986
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1986.tb04282.x
Subject(s) - nitrogenase , nitrogen fixation , biology , pisum , symbiosis , sativum , rhizobium , rhizobium leguminosarum , root nodule , strain (injury) , botany , rhizobia , microbial inoculant , rhizobiaceae , horticulture , bacteria , inoculation , genetics , anatomy
The effect of genetic factors in Rhizobium on host plant biomass production and on the carbon costs of N 2 fixation in pea root nodules was studied. Nine strains of Rhizobium leguminosarum were constructed, each containing one of three symbiotic plasmids in combination with one of three different genomic backgrounds. The resulting strains were tested in symbiosis with plants of Pisum sativum using a flow‐through apparatus in which nodule nitrogenase activity and respiration were measured simultaneously under steady state conditions. Nodules formed by strains containing the background of JI6015 had the lowest carbon costs of N 2 fixation (7.10–8.10 μmol C/μmol N 2 ), but shoot dry weight of those plants was also smaller than that of plants nodulated by strains with the background of B151 or JI8400. Nodules formed by these two strain types had carbon costs of N 2 fixation varying between 11.26 and 13.95 μmol C/μmol N 2 . The effect of symbiotic plasmids on the carbon costs was relatively small. A time‐course experiment demonstrated that nodules formed by a strain derived from JI6015 were delayed in the onset of nitrogenase activity and had a lower rate of activity compared to nodules induced by a strain with the background of B151. The relationship between nitrogenase activity, carbon costs of N 2 fixation and host plant biomass production is discussed.