Contents of free amino acids in Scots pine needles from field sites with different levels of nitrogen deposition

Abstract

SUMMARYThe response of pine stands in areas with three different levels of nitrogen deposition was analysed on samples of the current year's needles. Each test area vYas subdivided into^ five test sites. Clear changes in the amounts of amino acids in relation to the nitrogen content of pine needles were found. Analyses were mainly focused on the amino acids glutamate (Glu), glutamine (Glo) and those forming the urea eycle. The concentration of Gin increased significantly with response to increasing needle nitrogen content. Arginine (Arg) accumulated dramatically (up to 100-fold) at high levels of needle nitrogen, but had the highest variation within the test sites. Ornithine (Orn) showed an increase only if the needle nitrogen content was very high. No clear relationship found in the case of Glu. Glutamine and Arg are useful bioindicators of nitrogen pollution in pine stands.

Nitrogen Fertilizer Factory Effects on the Amino Acid and Nitrogen Content in the Needles of Scots Pine

“…The selected sites were distinguished by similar, nitrogen-poor, sandy soils; therefore the detected differences in nitrogen concentration reflect the gradient of pollutants. The proportion between the amount of arginine and the corresponding concentration of nitrogen in the needles was similar to that described by Schmeink and Wild [19] and it was much lower than the data reported by Huhn and Schultz [9] or Nasholm et al [37].…”

“…Epicuticular wax observations on the surface of the needles revealed higher erosion only in the site 0.5 km away from the factory [25]. Our investigation shows that pollution is significantly expressed, but is not very high when compared with effects described in the literature that reach 20-to 100-fold increases [9,12] in arginine content. Note: M = mean; SD = standard deviation.…”

“…The gradient of nitrogen concentration in the needles was assessed on the selected plots over the period of 1995-2000, with the highest concentration (depending on year, 119 to 153%) documented in the site located 0.5 km from the factory. Significant correlations were determined between the total amino acid contents (r = 0.448 -0.939, p < 0.05), some free amino acid (arginine, aspartic acid, glutamic acid, lysine, threonine, and serine) contents (r = 0.418 -0.975, p < 0.05), and air pollutant concentration at the sites, the dis-was higher than the estimated amount of the element that could enter biomass [8,9].…”

“…It has been shown that, in the presence of high ammonia concentration, trees absorb more ammonia than the amount that can be utilized for protein synthesis; therefore nitrogen accumulates in the form of the arginine [10,11], the amount of which in the needles may increase by several up to a hundred times [1,7,9,10,12]. The alterations in N flux affect the arginine content in the needles within an interval[l3,14] of several hours.…”

Potential Approaches to Developing Lichen-Based Critical Loads and Levels for Nitrogen, Sulfur and Metal-Containing Atmospheric Pollutants in North America

“…Nitrogenrich free amino acids, especially arginine, significantly increased in the needles with high nitrogen concentration (Hällgren and Näsholm, 1988;Van Dijk and Roelofs, 1988;Näsholm and Ericsson, 1990;Pietilä et al, 1991;Balsberg-Påhlsson, 1992). Arginine concentrations in foliage are suggested to be a sensitive indicator for nitrogen input (Edfast et al, 1990;Huhn and Schulz, 1996). In Sweden, arginine concentrations of coniferous foliage >5 µmol g dw -1 has been linked to forest stands susceptible to NO 3 -leaching (Näsholm et al, 1997), because arginine accumulation in trees corresponds to decreased uptake rates of NH 4 + , leaving NH 4 + ions available for nitrification followed by NO 3 -leaching (Näsholm et al, 1997).…”