Search

Abstract: Temperate species of Hypomyces and Cladobotryum that produce the red pigment aurofusarin are common on agaricoid and polyporoid basidiomata of species from five orders of Agaricomycetes. Several cause cobweb disease of commercially cultivated mushrooms resulting in serious losses. We sequenced rpb1, rpb2, tef1, and FG1093 regions in 90 wild strains and 30 strains from mushroom farms, isolated from Europe, North America, Africa, Asia, Australia, and New Zealand. Multigene analyses support the distinctness of five species but reveal Hypomyces rosellus to be paraphyletic, comprising several cryptic lineages. Hypomyces rosellus s. str. is characterised by wide dispersal and gene flow across Eurasia but does not occur in North America. Instead, the lineages from the West and the East Coast appear distinct, having given rise to species inhabiting the Southern Hemisphere. Our results reveal wide misuse of the name H. rosellus, especially for cobweb isolates. The majority of these belong to Hypomyces odoratus, including a weakly supported group of fungicide-resistant strains from Europe and North America sharing identical sequence data. New collections are presented for Cladobotryum rubrobrunnescens and Cladobotryum tenue as well as Cladobotryum multiseptatum and Hypomyces dactylarioides, all previously known only from their type material. The former species pair occurs in Europe and the latter in Australia and New Zealand. Separate lineages appear to be maintained by geographic isolation in North America and temperate Australasia but by host specialisation in the species occurring sympatrically in Europe and Asia. Both specialist and generalist host use strategies have evolved in the group. Although teleomorphs are known in most of the species and unnamed lineages, analyses of the five-gene regions suggest the prevalence of clonal reproduction in H. odoratus. This can be the reason for its success in mushroom farms, also facilitating the spread of fungicide resistance. While tef1 and rpb2 can be recommended for species delimitation, low variation, not exceeding 1 % in the whole ingroup, impeaches the use of ITS as a barcoding gene region in this group of fungi. [Copyright &y& Elsevier]

Host specificity of the mycoparasite Hypomyces microspermus to the Xerocomus chrysenteron group has been observed, but primarily from European collections. Our objectives were to test host specificity among Hypomyces spp. associated with boletes in California oak-woodlands, investigate population biology of these parasites, and to initiate studies on host-parasite coevolution. Bolete samples were collected from four locations separated by up to 600 km. Hypomyces isolates were cultured and host tissue samples taken for molecular identification. Based on AFLP analysis, four distinct Hypomyces clades were found with little genotypic diversity within each group. ITS-rDNA regions of selected isolates from each group were sequenced and analyzed along with sequences from a previously published phylogeny. Isolates from two AFLP groups clustered with H. microspermus whereas isolates from the other two AFLP groups clustered with H. chrysospermus. ITS-RFLP followed by sequence analysis identified three bolete hosts: (1) X. dryophilus; (2) a Xerocomus species closely related to X. dryophilus with affinities to X. chrysenteron; and (3) a Xerocomus species related to the X. subtomentosus group, which is not closely related to X. dryophilus and X. chrysenteron. H. microspermus infected X. dryophilus and the species with affinities to X. chrysenteron, whereas H. chrysospermus infected the species with affinities to X. chrysenteron and the species related to the X. subtomentosus group. These results support previous observations that H. microspermus is host-specific to the X. chrysenteron group, and that H. chrysospermus is more of a generalist pathogen. We also conclude that host-parasite coevolution studies within this system will not be possible until a phylogeny of North American boletes is in place. [ABSTRACT FROM AUTHOR]