Copper deficiency or toxicity in ectomycorrhizal pines?

Abstract

features but not others, and host specificity was less important than assumed, with evidence for host-shifts during the evolution of the genus (pp. 41-56). The recognition of a new lignicolous species of Marchandio-myces, a genus hitherto only including lichenicolous species, also provides evidence of substrate switches as it is closest to the lichenicolous M. corallinus but has M. aurantiacus (which is also lichenicolous) as the sister group ; it is suggested that in this case the lichenicolous habit arose secondarily on two separate occasions from an ancestral lignicolous one (pp. 57-70). The edible Pleurotus eryngii varies considerably morphologically and several varieties have been distinguished. A comparative study of 154 strains using RAPDs and minisatellites showed correlations with fruit body numbers and weights, but not with geographical locations nor taxonomic groupings ; a high level of heterogeneity exisited within populations (pp. 71-80). In contrast, variability in the charcoal root rot pathogen, Macrophomina phaseolina, examined by SSR and microsatellite markers, revealed three major groups correlated with hosts (soybean vs cotton) and geographical origins (pp. 81-86). In order to further advance precise identifications of Alternaria species, restriction maps of the IGS region of nrDNA were constructed for 15 species and revealed both conserved and and variable domains, the latter showing considerable differences amongst the taxa (pp. 87-95). Two specific primers have been designed and tested for the detection of Sclerotinia pseudotuberosa, causal agent of black rot of Castanea sativa fruits, and were capable of detecting the fungus when growing en-dophytically and in picogram quantities (pp. 96-102). The effect of the biocontrol fungus Phlebiopsis gigantea on Heterobasdion colonization on conifer stump, has been examined by denaturing gradient gel electro-phoresis of SSU rDNA fragments obtained directly by PCR from the wood ; the treatment did not appear to reduce overall fungal diversity, and the method is a promising one for the analysis of fungal communities on stumps (pp. 103-114). Using lignin peroxidase and laccase gene-specific PCR primers, laccase genes proved widespread amongst the basidiomycetes tested and were also discovered for the first time in Xylariaceae, although in that case the enzymes were not produced in vitro as they were in the basidiomycetes (pp. 115-124).