LIMING INDUCED STIMULATION OF THE AMINO-ACID-METABOLISM IN MYCORRHIZAL ROOTS OF NORWAY SPRUCE (PICEA-ABIES [L] KARST)

Localization and activity of three enzymes involved in the amino acid metabolism of ectomycorrhizas were investigated within an interdiscipl inary experiment performed in a mature Norway spruce stand in Southern Germany (Hoglwald). The enzymes NAD-glutamate dehydrogenase and aspar tate aminotransferase were present in root cells, whereas aminopeptida se was found in mycorrhizas of Norway spruce such as ''Piceirhiza nigr a'' and those with the fungi Cenococcum geophilum, Elaphomyces sp., Ru ssula ochroleuca and Tylospora sp. Mycorrhizas growing in the humus la yer contained about double the amount of protein found in those taken from the upper mineral soil (0-5 cm). Acid irrigation of the soil had no effect on the activity of any of the investigated enzymes, soluble protein or total N-contents irrespective of whether roots were taken f rom the organic layer or from the upper mineral soil. Liming, however, stimulated the activity of the three enzymes in mycorrhizas of the or ganic layer (O-f + O-h) whereas it had no effect on the activity of th e investigated enzymes of mycorrhizas in the upper mineral soil. This effect is attributed to increased contents of soluble organic nitrogen compounds in the soil of the limed plots as compared to the unlimed p lots.