Regulation of organic and inorganic nitrogen uptake in Scots pine ( Pinus sylvestris ) seedlings. Öhlund, J. & Näsholm, T. Tree Physiology, 24(12):1397–1402, December, 2004.
Regulation of organic and inorganic nitrogen uptake in Scots pine ( Pinus sylvestris ) seedlings [link]Paper  doi  abstract   bibtex   
Plants possess regulatory mechanisms that enhance nitrogen (N) uptake under conditions of spatial and temporal variation in N availabilily. Study of regulatory mechanisms has focused almost exclusively on the uptake of inorganic N sources (i.e., ammonium (NH 4+ ), nitrate (NO 3− )). Several lines of evidence, however, suggest that amino acids may constitute a potential source of N for a number of plant species, including conifers. In the present study, we investigated the uptake of amino acids and inorganic N in Scots pine ( Pinus sylvestris L.) seedlings grown at different N concentrations. We compared the uptake rate of the individual N sources using U-[ 13 C 2 ], [ 15 N]-glycine, U-[ 13 C 6 ], [ 15 N 4 ]-arginine, 15 NH 4 , or 15 NO 3 , and tested the short-term effect of N supply on the uptake rate of glycine, arginine and in field-grown Scots pine seedlings. Our data indicate that Scots pine seedlings can absorb substantial amounts of N in the form of intact arginine and glycine molecules. The data also suggest that Scots pine seedlings down-regulate their uptake of NH 4+ -N and arginine-N, but not of glycine-N in response to increased endogenous N concentrations.
@article{ohlund_regulation_2004,
	title = {Regulation of organic and inorganic nitrogen uptake in {Scots} pine ( {Pinus} sylvestris ) seedlings},
	volume = {24},
	issn = {0829-318X},
	url = {https://doi.org/10.1093/treephys/24.12.1397},
	doi = {10.1093/treephys/24.12.1397},
	abstract = {Plants possess regulatory mechanisms that enhance nitrogen (N) uptake under conditions of spatial and temporal variation in N availabilily. Study of regulatory mechanisms has focused almost exclusively on the uptake of inorganic N sources (i.e., ammonium (NH 4+ ), nitrate (NO 3− )). Several lines of evidence, however, suggest that amino acids may constitute a potential source of N for a number of plant species, including conifers. In the present study, we investigated the uptake of amino acids and inorganic N in Scots pine ( Pinus sylvestris L.) seedlings grown at different N concentrations. We compared the uptake rate of the individual N sources using U-[ 13 C 2 ], [ 15 N]-glycine, U-[ 13 C 6 ], [ 15 N 4 ]-arginine, 15 NH 4 , or 15 NO 3 , and tested the short-term effect of N supply on the uptake rate of glycine, arginine and in field-grown Scots pine seedlings. Our data indicate that Scots pine seedlings can absorb substantial amounts of N in the form of intact arginine and glycine molecules. The data also suggest that Scots pine seedlings down-regulate their uptake of NH 4+ -N and arginine-N, but not of glycine-N in response to increased endogenous N concentrations.},
	number = {12},
	urldate = {2021-10-14},
	journal = {Tree Physiology},
	author = {Öhlund, Jonas and Näsholm, Torgny},
	month = dec,
	year = {2004},
	pages = {1397--1402},
}

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