Cedergreen Nina, Madsen Tom V
Institute of Agricultural Sciences, The Royal Veterinary and Agricultural University, Højbakkegård Allé 9, DK-2630 Taastrup, Denmark.
Department of Plant Ecology, Aarhus University, Nordlandsvej 68, DK-8240 Risskov, Denmark.
New Phytol. 2004 Feb;161(2):449-457. doi: 10.1046/j.1469-8137.2003.00936.x. Epub 2003 Nov 25.
• The regulation of NO uptake kinetics and reduction in relation to long- and short-term changes in irradiance was explored in roots and photosynthetic tissues of Lemna minor. • The NO uptake kinetics, nitrate reductase activity, plant morphology, chlorophyll and tissue NO , organic-N, starch and sugars were measured on roots and fronds of L. minor grown at four combinations of irradiance- and NO availability. • Long-term acclimatizations paralleled those of terrestrial plants. Short-term changes in irradiance, however, changed frond NO uptake proportionally with frond chlorophyll and N content, indicating a relationship between responsiveness and the metabolic potential of the plants. Root uptake changed to balance the change in frond uptake keeping whole plant uptake varying by < 40%. Nitrate reductase activity was primarily located in the roots and was correlated with frond uptake, indicating a transport of NO from shoot to root before reduction. • This study shows that irradiance can affect the contribution of root and leaf uptake by aquatic plants and that roots play a major role in NO reduction despite large foliar uptake.
• 研究了小浮萍根系和光合组织中一氧化氮（NO）吸收动力学的调节以及与光照长期和短期变化相关的还原作用。
• 对生长在光照和NO供应四种组合条件下的小浮萍根系和叶状体，测定了其NO吸收动力学、硝酸还原酶活性、植物形态、叶绿素以及组织中的NO、有机氮、淀粉和糖类。
• 长期适应性变化与陆生植物相似。然而，光照的短期变化使叶状体NO吸收与叶状体叶绿素和氮含量成比例变化，表明植物的响应性与代谢潜力之间存在关联。根系吸收发生变化以平衡叶状体吸收的变化，使整株植物吸收量的变化小于40%。硝酸还原酶活性主要位于根系，且与叶状体吸收相关，表明NO在还原之前从地上部分运输到根系。
• 本研究表明，光照可影响水生植物根系和叶片吸收的贡献，并且尽管叶部吸收量大，但根系在NO还原中起主要作用。
