Investigation of the breeding biology of the agaric Crinipellis perniciosa (causal agent of witches' broom disease of cocoa in South America) found that two distinct breeding strategies exist among the four known biotypes of the fungus, which are specific to cocoa (C-biotype), solanaceous hosts (S-biotype), Bixa orellana (B-biotype) and liana vines (L-biotype). The homomictic (primary homothallic) behaviour of the C-biotype was confirmed and single basidiospore isolates (SSIs) of the S-biotype and B-biotype were found to behave in a similar manner. The mycelia of most SSIs of the L-biotype did not bear clamp connections and pairings between sibling SSIs established that an outcrossing mechanism under the control of two unlinked mating type factors was operating (i.e. bifactorial heterothallism). These matings also suggested that one of the mating factors has a twogene structure. The occurrence of bi-and trinucleate basidiospores and SSIs bearing true or false clamp connections suggests that the L-biotype exhibits a limited degree of secondary homothallism.

The agaric Crinipellis perniciosa (Tricholomataceae) is a hemibiotrophic pathogen which causes witches' broom disease of cacao and has recently decimated the Brazilian cacao industry. In addition to the pathogenic cacao (C-) biotype, other biotypes are found in association with unrelated plant taxa, notably bignoniaceous lianas (L-biotype), solanaceous hosts (S-biotype), and the shrub Heteropterys acutifolia (H-biotype). The Cand S-biotypes are non-outcrossing and form broom symptoms on hosts, whereas the L-biotype is outcrossing and asymptomatic. Phylogenetic analysis of several regions of the rRNA locus revealed near identity between C-and S-biotype isolates from diverse locations, with the Land Hbiotypes forming separate groupings. Preliminary analysis of sequence data from Moniliophthora roreri, causal agent of frosty pod disease, indicates that this morphologically distinct pathogen may be closely related to C. perniciosa. Similarities in host infection between C. perniciosa and M. roreri have B02084; Online publication date

The paper presents the first proof-of principle study of metabolite profiles of the interacting mycelial fronts of a wood decomposer basidiomycete, Stereum hirsutum, paired with two competitor basidiomycetes, Coprinus disseminatus and C. micaceus, using TLC and GC-TOF-MS profiling. GC-TOF-MS profiles were information rich, with a total of 190 metabolite peaks detected and more than 120 metabolite peaks detected per sample. The metabolite profiles were able to discriminate between the interactions of S. hirsutum with the two species of Coprinus. In confrontation with C. micaceus, where S. hirsutum mycelial fronts always overgrew those of C. micaceus, there were down-regulations of metabolites in the interaction zone, compared to monocultures of both S. hirsutum and C. micaceus. In contrast, in pairings with C. disseminatus, whose mycelia overgrew those of S. hirsutum, there were some up-regulations compared with monoculture controls, the majority of the metabolites being characteristic of the S. hirsutum monoculture profile. These differences indicate that up-regulation of metabolites in the mycelia of S. hirsutum may be connected to a defensive role or to stress. The results also show proof of principle for the employment of metabolic profiling for biological discovery studies of metabolites produced by fungi that could be applied to natural product screening programmes.

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