Atkin Owen K, Villar Rafael, Cummins W Raymond
Department of Botany, University of Toronto, L5L 1C6, Mississauga, Ontario, Canada.
Dept de Ecologia Facultad de Biologia, Apartado 1095, E-4180, Sevilla, Spain.
Oecologia. 1993 Nov;96(2):239-245. doi: 10.1007/BF00317737.
The ability to utilize NO in seven high arctic plant species from Truelove Lowland, Devon Island, Canada was investigated, using an in vivo assay of maximum potential nitrate reductase (NR) activity and applications of N. Plant species were selected on the basis of being characteristic of nutrient-poor and nutrient-rich habitats. In all species leaves were the dominant site of NR activity. Root NR activity was negligible in all species except Saxifraga cernua. NO availability per se did not appear to limit NR activity of the species typically found on nutrient-poor sites (Dryas integrifolia, Saxifraga oppositifolia, and Salix arctica), or in Cerastium alpinum, as leaf NR activities remained low, even after NO addition. NO uptake was limited in D. integrifolia and Salix arctica. However, the lack of field induction of NR activity in C. alpinum and Saxifraga oppositifolia was not due to restricted nitrate uptake, as NO labelled NO entered the roots and shoots of both species. Leaf NR activity rates were low in three of the species typical of nutrient-rich habitats (O. digyna, P. radicatum and Saxifraga cernua), sampled from a site containing low soil NO . Additions of NO significantly increased leaf NR activity in these latter species, suggesting that potential NR activity was limited by the availability of NO . N labelled NO was taken up by O. digyna. P. radicatum and Saxifraga cernua. Although two species (D. integrifolia and Salix arctica) showed little utilization of NO , we concluded that five of the seven selected high arctic plant species (C. alpinum, O. digyna, P. radicatum, Saxifraga cernua and Saxifraga oppositifolia) do have the potential to utilize NO as a nitrogen source under field conditions, with the highest potential to utilize NO occurring in three of the species typically found on fertile habitats.
利用加拿大德文岛特鲁洛夫低地的七种北极高海拔植物体内最大潜在硝酸还原酶（NR）活性的体内测定法以及氮的施用，对这些植物利用一氧化氮（NO）的能力进行了研究。根据植物是否为贫营养和富营养栖息地的典型特征来选择植物种类。在所有物种中，叶片是NR活性的主要部位。除了垂头虎耳草外，所有物种的根系NR活性都可以忽略不计。对于通常生长在贫营养环境中的物种（整叶仙女木、极地虎耳草、北极柳）以及高山卷耳来说，NO本身似乎并不限制其NR活性，因为即使添加了NO，叶片NR活性仍然很低。整叶仙女木和北极柳对NO的吸收有限。然而，高山卷耳和极地虎耳草中NR活性缺乏田间诱导并非由于硝酸盐吸收受限，因为用NO标记的NO进入了这两个物种的根和茎。从土壤中NO含量低的地点采集的三种典型富营养栖息地的物种（二裂委陵菜、高山早熟禾和垂头虎耳草）的叶片NR活性速率较低。添加NO后，后三个物种的叶片NR活性显著增加，这表明潜在的NR活性受到NO可用性的限制。二裂委陵菜、高山早熟禾和垂头虎耳草吸收了用N标记的NO。虽然有两个物种（整叶仙女木和北极柳）对NO的利用很少，但我们得出结论，在野外条件下，七种选定的北极高海拔植物中有五种（高山卷耳、二裂委陵菜、高山早熟禾、垂头虎耳草和极地虎耳草）确实有潜力将NO用作氮源，其中在三种典型的肥沃栖息地物种中利用NO的潜力最大。
