FIG. 1.

Amino acids and urea in various components of the P. involutus-B. pendula symbiosis. (a and b) Amino acids and urea were measured in ECM (a) and in EM (b) of P. involutus-B. pendula microcosms. d. wt, dry weight. (c) Proportions of urea (white bars) and total amino acids (gray bars) were calculated and expressed as percentages of total N compounds measured; 100% represented 3.6, 1.3, 36.6, 112.5, and 19.3 nmol mg⁻¹ (dry weight), respectively, in ECM, EM, and NMR of P. involutus-B. pendula microcosms and in free-living mycelium grown on medium with 3.8 mM N (FLM +N) or on N-free medium (FLM −N). Amino acid and urea contents were determined by GC-MS analysis as described in Materials and Methods.