Ohlund Jonas, Näsholm Torgny
Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, SUAS, S-901 83 Umeå, Sweden.
Tree Physiol. 2004 Dec;24(12):1397-402. doi: 10.1093/treephys/24.12.1397.
Plants possess regulatory mechanisms that enhance nitrogen (N) uptake under conditions of spatial and temporal variation in N availability. Study of regulatory mechanisms has focused almost exclusively on the uptake of inorganic N sources (i.e., ammonium (NH4+), nitrate (NO3-). 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-[13C2], [15N]-glycine, U-[13C6], [15N4]-arginine, 15NH4, or 15NO3, 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 NH4+-N and arginine-N, but not of glycine-N in response to increased endogenous N concentrations.
植物拥有调控机制，可在氮素供应存在时空变化的条件下增强氮（N）的吸收。对调控机制的研究几乎完全集中在无机氮源（即铵（NH4+）、硝酸盐（NO3-））的吸收上。然而，有几条证据表明，氨基酸可能是包括针叶树在内的许多植物物种的潜在氮源。在本研究中，我们调查了在不同氮浓度下生长的苏格兰松（Pinus sylvestris L.）幼苗对氨基酸和无机氮的吸收情况。我们使用U-[13C2]、[15N]-甘氨酸、U-[13C6]、[15N4]-精氨酸、15NH4或15NO3比较了各氮源的吸收速率，并测试了氮供应对田间生长的苏格兰松幼苗中甘氨酸、精氨酸吸收速率的短期影响。我们的数据表明，苏格兰松幼苗能够以完整的精氨酸和甘氨酸分子形式吸收大量的氮。数据还表明，随着内源氮浓度的增加，苏格兰松幼苗会下调其对NH4+-N和精氨酸-N的吸收，但不会下调对甘氨酸-N的吸收。
