Effects of varied soil nitrogen supply on Norway spruce (Picea abies [L.] Karst.)
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- Wallenda, T., Schaeffer, C., Einig, W. et al. Plant Soil (1996) 186: 361. doi:10.1007/BF02415531
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The response of carbohydrate metabolism in 3-year-old Norway spruce plants to an increased amount of nitrogen supply to a N-poor forest soil was investigated in a pot experiment. After 7 months of treatment we found a decreased amount of starch in both needles and roots, together with decreased amounts of sucrose in needles of those plants grown under an enhanced inorganic N supply. In addition, the activity and the protein amount of the anaplerotic enzyme phosphoenolpyruvate carboxylase (PEPC) and the activity of NADP-dependent isocitrate dehydrogenase (IDH) were clearly increased. The activity of sucrose phosphate synthase (SPS) and the pool size of fructose 2,6-bisphosphate (F26BP) were not affected by high supply of inorganic N. These data indicate a shift of carbon flow from starch formation towards an enhanced provision of carbon skeletons for N assimilation and shoot growth. In parallel, we found decreased contents of fungus-specific compounds (ergosterol, mannitol, trehalose) in roots, which are indicators of a decreased colonization by ectomycorrhizal fungi, probably as a result of a changed allocation and partitioning of photoassimilates due to an increased N supply.
Key wordsectomycorrhiza fungus-specific compounds isocitrate dehydrogenase nitrogen Picea abies phosphoenolpyruvate carboxylase
NADP-dependent isocitrate dehydrogenase
phosphoenolpyruvate carboxylase, SPS-sucrose phosphate synthase