Effect of Nodulation on the Expression of Nitrate Reductase Activity in Pea Cultivars

Abstract

SUMMARYNitrate reductase activity (NRA) was measured in leaves, stems, roots and nodules of four cultivars of Pisum sativum L. supplied with 2 mM KNOg and nodulated by selected Rhizobium leguminosarum strains. As a control, non-nodulated (uninoculated) plants were grown in the same nutrient medium. NRA was determined by an in vitro assay; it varied widely among strains and cultivars. Although differences in tissue NRA in nodulated plants were mainly related to cultivar genotype, nodulation much affected the distribution of NRA within the plant. There was also some cultivar x bacteria strain effect. Non-nodulated plants had higher leaf and root NRA than nodulated cultivars, but nodulated plants had twice as high stem NRA as nonnodulated plants. These differences correlated with nitrate concentrations which were depressed in leaves and roots, and increased in stems, of nodulated plants Nitrate accumulation was increased in leaves, stems and roots of nodulated plants in comparison with non-nodulated ones. There were no differences in the root to shoot ratio between nodulated and non-nodulated plants. The relationships between tissue nitrate reduction and nodulation are discussed.

Effect of presowing treatment of seeds with insecticides on parameters related to nodulation and nitrate reduction in soybean [Glycine max (L.) Merr.]

“…In the treatment with Carbodan 35 ST, applied at the doses of 1 and 2 L/100 kg seeds, the greatest increase in the activity of this enzyme was observed. Our data confirm the opinion of other authors that plants can accumulate and reduced nitrates in stems due to the various factors (Andrews et al, 1984;Ligero et al, 1987).…”

Nitrate reductase and nitrite reductase activity in free-living cells and bacteroids of Rhizobium loti

“…Re-NRA and NiRA in R. loti 205 gardless of the host plant used for inoculations, the cytosol fraction from nodules formed by T1 averaged 1.4 and 1.7 times more NRA and NiRA, respectively, than that from nodules initiated by U226 (Table 2). Both the plant genotype and the strain used for inoculation have been reported to affect the expression of NRA and NiRA in leguminous nodules (Caba et al, 1990;Ligero et al, 1987). Both the plant genotype and the strain used for inoculation have been reported to affect the expression of NRA and NiRA in leguminous nodules (Caba et al, 1990;Ligero et al, 1987).…”

In vivonitrate reductase activity in ryegrass (Lolium perenne) and white clover (Trifolium repens): Differences due to nitrogen supply, development, and plant part

“…The low-N plants were observed to have active N-fixing nodules, whereas, although the high-N plants had nodules, they were pale, and therefore deemed to be inactive (Gordon & James 1997). In soybean and pea plants, active N-fixation has been associated with a decrease in NRA (Conejero et al 1986;Ligero et al 1987;Vasilieva et al 1999). There was no spill-over (i.e., the phenomenon, reported by Andrews (1986) whereby NO3 for reduction appears in the shoot causing a stimulation of NRA only after saturation of NRA occurs in the root).…”