Potato dextrose agar (PDA) is one of the most commonly used media for the isolation and cultivation of fungi, with morphological features and pigmentation in culture often being important for identification of cultures. Cultivation of various fungi on different brands and batches of powdered (commercial) potato dextrose media revealed deficient pigmentation in five of 10 media tested. Reduced pigmentation on these media was correlated with low levels of copper and colony colour was restored by the addition of copper. Deficient pigmentation was most pronounced when copper levels in the medium were below 50 ng mL(-1) (50 p.p.b.; 0.8 microM). Differences in pigmentation and laccase activity of spore and mycelial preparations were quantified for representative species belonging to the genera Aspergillus, Fusarium, Trichoderma, Cladosporium and Penicillium grown on PDA containing different amounts of copper. A strong positive correlation between laccase activity and copper levels was observed. Differences were also found between batches of raw potatoes, with organically cultivated tubers having higher copper levels than those grown by conventional methods, possibly because of the use of copper-based fungicides in the former case. Routine addition of 1000 ng mL(-1) copper (or standard trace element solutions) to PDA and other undefined media is advised to avoid atypical culture pigmentation and possibly other consequences of reduced activity of copper-requiring enzymes.
Several lines of evidence suggest that the agaricoid, non-ectomycorrhizal members of the family Hygrophoraceae (waxcaps) are biotrophic with unusual nitrogen nutrition. However, methods for the axenic culture and lab-based study of these organisms remain to be developed, so our current knowledge is limited to field-based investigations. Addition of nitrogen, lime or organophosphate pesticide at an experimental field site (Sourhope) suppressed fruiting of waxcap basidiocarps. Furthermore, stable isotope natural abundance in basidiocarps were unusually high in N and low in C, the latter consistent with mycorrhizal nutritional status. Similar patterns were found in waxcap basidiocarps from diverse habitats across four continents. Additional data from C analysis of basidiocarps and C pulse label experiments suggest that these fungi are not saprotrophs but rather biotrophic endophytes and possibly mycorrhizal. The consistently high but variable δ N values (10-20‰) of basidiocarps further indicate that N acquisition or processing differ from other fungi; we suggest that N may be derived from acquisition of N via soil fauna high in the food chain.
The large decline in plant and animal diversity of semi-natural grasslands resulting from the introduction of modern agricultural practices in the 1940"s has been well documented and such changes are also suspected of causing the decline in the abundance and diversity of macrofungi in these habitats. We conducted repeated surveys at 48 selected grassland sites around Wales to record the presence and abundance of fruitbodies (FBs) of grassland macrofungi belonging to the taxa Clavariaceae, Hygrocybe, Entoloma, Geoglossaceae, Dermoloma (also Porpoloma and Camarophyllopsis spp.) which are grouped collectively as "CHEGD" fungi (acronym of group names) and considered typical of nutrient poor "waxcap" grasslands. A total of 111 CHEGD species (of the ca. 200 species previously found in UK/Ireland) were recorded. That these included one
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.