Figure 1.
A sampling of the diversity of color and form within the genus Amanita.
Clockwise, from top left, Amanita muscaria subsp. flavivolvata, Amanita frostiana, Amanita jacksonii, an undescribed Amanita species, the saprotrophic Amanita manicata, and Amanita phalloides.
Figure 2.
Maximum likelihood phylogeny of Amanita and closely related taxa.
Support values at nodes indicate maximum likelihood bootstrap (MLB)/Bayesian posterior probability (BPP) values. Thick branches indicate branches with >90% MLB and >0.95 BPP. Boxes along right indicate presence/absence of three cellulase genes: endoglucanase (E), cellobiohydrolase (C), and beta-glucosidase (ß). Black = present. White = absent. Species highlighted in grey are kept as cultures and were used for experimental assessment of saprotrophy (see text). Inset indicates putative role and location of cellulases in cellulose degradation pathway. Colors of branches are based on parsimony reconstructions of trophic status.
Figure 3.
Transcript abundance of a beta-glucosidase (bgl) and elongation factor 1-alpha (ef1-α) for three species of Amanita growing on glucose (G) or cellobiose (C).
A. th = Amanita thiersii (saprotrophic). A. co = Amanita cokeri (ectomycorrhizal). A. cr = Amanita crenulata (ectomycorrhizal).
Figure 4.
Experimental demonstration of the loss of cellulolytic saprotrophic capabilities by ectomycorrhizal Amanita species.
Fourteen species, including saprotrophic and ectomycorrhizal Amanita and two saprotrophic Volvariella species, were grown on sterile grass litter to test for the use of litter as a sole carbon source. Enzyme activities of endoglucanase (E), cellobiohydrolase (C) and beta-glucosidase (ß) were also measured. The same species were grown on media with a protein (casein hydrolysate) as sole nitrogen source. Colony diameter as well as clearing of milk agar was measured to indicate growth on protein and protease activity, respectively. Values of cellulolytic and proteolytic growth and activity are expressed as relative to the maximum value (from 0 to 1) for each parameter across the species. The difference in growth between ectomycorrhizal and saprotrophic species on litter is highly significant, according to phylogenetically independent contrasts (F1,11 = 7.84, p = 0.017). Contrasts for all other data were not significant.