Nitrate reductase is induced in red spruce by NO sub 2 and HNO sub 3 vapor

Journal Article · Sat Apr 01 00:00:00 EST 1989 · Plant Physiology, Supplement; (USA)

OSTI ID:6597375

Norby, R J; Hanson, P J ^[1]; Weerasuiya, Y ^[2]

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1. Oak Ridge National Lab., TN (USA)
2. College of Wooster, OH (USA)

The activity of nitrate reductase (NR) in needles of red spruce (Picea rubens Sarg.) trees is normally very low: 220 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1} in 1-year-old nursery-grown seedlings and 47 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1} in plants excavated from a high-elevation spruce forest. The assimilation of nitrogen oxide pollutants absorbed from the atmosphere by red spruce trees may, therefore, require that NR is induced in the needles. To test for induction of NR, 1-year-old, nursery-grown red spruce seedlings were exposed to NO{sub 2}, HNO{sub 3} vapor, or acid mist containing nitrate, and the activity of NR in needles was measured using an in vivo assay. One day after exposure to NO{sub 2} (75 nl{center dot}l{sup {minus}1}) began, NR activity had increased to 765 nmol{center dot}g{sup {minus}1}{center dot}h{sup {minus}1}, more than 3 times that of unexposed control plants. During the 7-day exposure, NR activity of the treated seedlings declined 36%, but it remained significantly higher than that of controls. One day after exposure ended, NR activity returned to the control level. Forest-frown seedlings exhibited a similar response to NO{sub 2}, but at a much lower level. Nitric acid vapor (75 nl{center dot}l{sup {minus}1}) also induced NR in red spruce needles, and the pattern and magnitude of response were similar to that with NO{sub 2}, except that the NR activity did not return to control levels until 2 days after exposure ended. Exposure of seedlings to simulated acid mist containing nitrate (pH 3.5 and pH 5.0) did not result in a significant change in NR activity. These results indicate that red spruce is capable of assimilating NO{sub 2} and HNO{sub 3} vapor, and that hypotheses of forest decline based on foliar assimilation of pollutant nitrogen oxides are tenable.

• OSTI ID: 6597375
• Journal Information: Plant Physiology, Supplement; (USA), Vol. 89:4; ISSN 0079-2241
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
FORESTS
PRODUCTIVITY
NITRIC ACID
METABOLISM
NITROGEN DIOXIDE
OXIDOREDUCTASES
ENZYME ACTIVITY
ACID RAIN
AIR POLLUTION
PLANT GROWTH
SEEDLINGS
SPRUCES
VAPORS
ATMOSPHERIC PRECIPITATIONS
CHALCOGENIDES
CONIFERS
ENZYMES
FLUIDS
GASES
GROWTH
HYDROGEN COMPOUNDS
INORGANIC ACIDS
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
PINOPHYTA
PLANTS
POLLUTION
RAIN
TREES
560300* - Chemicals Metabolism & Toxicology