Mycoparasite Hypomyces odoratus infests Agaricus xanthodermus fruiting bodies in nature

Abstract

Mycopathogens are serious threats to the crops in commercial mushroom cultivations. In contrast, little is yet known on their occurrence and behaviour in nature. Cobweb infections by a conidiogenous Cladobotryum -type fungus identified by morphology and ITS sequences as Hypomyces odoratus were observed in the year 2015 on primordia and young and mature fruiting bodies of Agaricus xanthodermus in the wild. Progress in development and morphologies of fruiting bodies were affected by the infections. Infested structures aged and decayed prematurely. The mycoparasites tended by mycelial growth from the surroundings to infect healthy fungal structures. They entered from the base of the stipes to grow upwards and eventually also onto lamellae and caps. Isolated H. odoratus strains from a diseased standing mushroom, from a decaying overturned mushroom stipe and from rotting plant material infected mushrooms of different species of the genus Agaricus while Pleurotus ostreatus fruiting bodies were largely resistant. Growing and grown A. xanthodermus and P. ostreatus mycelium showed degrees of resistance against the mycopathogen, in contrast to mycelium of Coprinopsis cinerea . Mycelial morphological characteristics (colonies, conidiophores and conidia, chlamydospores, microsclerotia, pulvinate stroma) and variations of five different H. odoratus isolates are presented. In pH-dependent manner, H. odoratus strains stained growth media by pigment production yellow (acidic pH range) or pinkish-red (neutral to slightly alkaline pH range).

Lessons on fruiting body morphogenesis from genomes and transcriptomes of Agaricomycetes

“…Agaricomycete fruiting bodies (mushrooms) are, due to the concentration of biomass, attractive targets of predators, parasites and pathogens. Accordingly, these structures are known to be subject to grazing by slugs, to infestations with larvae of phorid and sciarid flies and to infections by bacteria and molds (Wood et al 2004;Krivosheina 2008;Lakkireddy et al 2020;M et al 2020a). Since mushrooms are the sexual reproduction organs and a considerable investment in terms of resources and energy, Agaricomycetes have evolved several strategies for the protection and defense of these structures (Künzler 2018).…”

Mycelium vs. Fruiting Bodies of Edible Fungi—A Comparison of Metabolites

“…Complex consortia consisting of thermophilic proteobacteria and actinobacteria and the thermophilic fungus Mycothermus thermophilus were identified [ 86 ]. Certain bacteria may protect the pileus against other bacteria [ 87 ], while the interaction between asco- and basidiomycetes often finishes with fruiting body decay [ 88 ].…”

“…They thrive on most of the substrates shown in Table 1 by quickly inducing large enzymatic networks (own experiments, data not shown). As a result, the composition of the fruiting bodies depends on the growth substrate [ 33 , 55 , 57 , 60 , 67 , 72 , 74 ], the strain chosen [ 33 , 60 , 74 , 75 , 76 , 77 , 78 , 80 ], its developmental stage [ 29 , 30 , 31 , 32 , 38 ], and the associated adverse or beneficial microbial community [ 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 ] and is thus variable like no other food. The same applies to the mass production of fungal mycelia.…”

Control of Fungal Diseases in Mushroom Crops while Dealing with Fungicide Resistance: A Review

“…Among them, C. dendroides [ 26 ], C . mycophilum [ 79 ], C. protrusum [ 25 ], or C. varium [ 80 ] have been described as parasites of cultivated mushrooms but also infecting mushrooms in the wild [ 81 ]. Cladobotryum spp.…”

“…Cobweb is a globally widespread pathology whose causative agent corresponds with several Ascomycota species described as harmful in different mushroom-producing countries and all belonging to the genera Cladobotryum spp. Among them, C. dendroides [26], C. mycophilum [79], C. protrusum [25], or C. varium [80] have been described as parasites of cultivated mushrooms but also infecting mushrooms in the wild [81]. Cladobotryum spp.…”