Free amino acids and protein in Scots pine seedlings cultivated at different nutrient availabilities

Abstract

Scots pine (Pinus sylvestris L.) seedlings of a provenance from northern Sweden were cultivated hydroponically for 7 weeks in a climate chamber. The nutrient solution contained either 2.5 (low-N) or 50 (high-N) mg N l(-1) with other essential elements added in a fixed optimal proportion to the nitrogen. After 5 and 7 weeks, the seedlings were analyzed for growth, total nitrogen and other essential nutrients, protein and free amino acids. Low-N seedlings grew more slowly and had higher root/shoot ratios than high-N seedlings. With respect to total nitrogen, the effect of the lower nutrient supply was mainly on the nitrogen content of the whole plant and the allocation of nitrogen among tissues, not on tissue nitrogen concentration. This was also the case for potassium, phosphorus, calcium and magnesium. The proportions by weight among these macronutrients in the whole seedlings were similar in both nutrient regimes. The proportion and concentration of sulfur were significantly lower in low-N seedlings than in high-N seedlings, because of a lower net uptake of sulfur than of other macronutrients. The shoot, needles and stem of low-N seedlings had higher concentrations of free amino acids and lower concentrations of protein than the shoot, needles and stem of high-N seedlings. Arginine dominated the pool of free amino acids in the low-N seedlings, whereas glutamine predominated in the high-N seedlings. We conclude that Scots pine seedlings accumulated soluble nitrogen as arginine when net protein synthesis was limited by factors other than nitrogen availability. Nutritional imbalance, as revealed by growth characteristics and a suboptimal proportion and concentration of sulfur in the seedlings, probably affected synthesis of S-amino acids, resulting in the diversion of assimilated nitrogen to arginine instead of protein.

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

“…In some reports, changes in arginine amount were documented in relation to nutrient deficiency in the needles [17,29,38]. Neither macro nor micronutrient deficiency was found at the sites of the present study during 1997 estimations, nor were significant differences in element concentrations among the sites [24] revealed.…”

Fungal diseases in forest nurseries in Finland

“…In addition factors that retard shoot maturation increase host-plant susceptibility to G. abietina infection (Donaubauer 1972, Uotila 1988. For example, increased nitrogen levels (Ylimartimo 1991, Barklund 1993, incomplete lignification due to rapid growth, low temperatures and light intensity during the summer (Petäistö and Repo 1988) and certain amino acids that stimulate G. abietina (Gezelius and Näsholm 1993).…”

Ecophysiology of selected tree species in different plant communities at the periphery of the Atlantic Forest of SE-Brazil II. Spatial and ontogenetic dynamics in Andira legalis, a deciduous legume tree

“…The significant increase in Asn concentrations in the roots between bud break and unfolding of new flush may be due to increased N uptake from the soil, increased mobilisation of N compounds originating from fixed N 2 , or enhanced remobilisation of stored nitrogen. The high concentrations of soluble non-protein N-compounds in the xylem in the early stages (bud break and expanding leaves) indicate transport of N remobilised from storage pools in the stem and/or the roots (Gezelius and Näsholm 1993;Schmidt and Stewart 1998). However, in these early stages of leaf development a significant part of N consumed by the growing leaves has to be supplied additionally via phloem transport from the storage tissues (Da Silva and Shelp 1990;Geßler et al 1998) resulting in increased total soluble N concentrations in phloem exudates when leaves were not yet fully expanded.…”