Contribution to the taxonomy and pathogenicity of fungicolous Verticillium species. I. Taxonomy

Manipulating multi-level selection in a fungal entomopathogen reveals social conflicts and a method for improving biocontrol traits

Changes in parasite virulence are commonly expected to lead to trade-offs in other life history traits that can affect fitness. Understanding these trade-offs is particularly important if we want to manipulate the virulence of microbial biological control agents. Theoretically, selection across different spatial scales, i.e. between- and within-hosts, shapes these trade-offs. However, trade-offs are also dependent on parasite biology. Despite their applied importance the evolution of virulence in fungal parasites is poorly understood: virulence can be unstable in culture and commonly fails to increase in simple passage experiments. We hypothesized that manipulating selection intensity at different scales would reveal virulence trade-offs in a fungal pathogen of aphids, Akanthomyces muscarius. Starting with a genetically diverse stock we selected for speed of kill, parasite yield or infectivity by manipulating competition within and between hosts and between-populations of hosts over 7 rounds of infection. We characterized ancestral and evolved lineages by whole genome sequencing and by measuring virulence, growth rate, sporulation and fitness. While several lineages showed increases in virulence, we saw none of the trade-offs commonly found in obligately-killing parasites. Phenotypically similar lineages within treatments often shared multiple single-nucleotide variants, indicating strong convergent evolution. The most dramatic phenotypic changes were in timing of sporulation and spore production in vitro. We found that early sporulation led to reduced competitive fitness but could increase yield of spores on media, a trade-off characteristic of social conflict. Notably, the selection regime with strongest between-population competition and lowest genetic diversity produced the most consistent shift to early sporulation, as predicted by social evolution theory. Multi-level selection therefore revealed social interactions novel to fungi and showed that these biocontrol agents have the genomic flexibility to improve multiple traits-virulence and spore production-that are often in conflict in other parasites.

Redisposition of acremonium-like fungi in Hypocreales

Acremonium is acknowledged as a highly ubiquitous genus including saprobic, parasitic, or endophytic fungi that inhabit a variety of environments. Species of this genus are extensively exploited in industrial, commercial, pharmaceutical, and biocontrol applications, and proved to be a rich source of novel and bioactive secondary metabolites. Acremonium has been recognised as a taxonomically difficult group of ascomycetes, due to the reduced and high plasticity of morphological characters, wide ecological distribution and substrate range. Recent advances in molecular phylogenies, revealed that Acremonium is highly polyphyletic and members of Acremonium s. lat. belong to at least three distinct orders of Sordariomycetes, of which numerous orders, families and genera with acremonium-like morphs remain undefined. To infer the phylogenetic relationships and establish a natural classification for acremonium-like taxa, systematic analyses were conducted based on a large number of cultures with a global distribution and varied substrates. A total of 633 cultures with acremonium-like morphology, including 261 ex-type cultures from 89 countries and a variety of substrates including soil, plants, fungi, humans, insects, air, and water were examined. An overview phylogenetic tree based on three loci (ITS, LSU, rpb2) was generated to delimit the orders and families. Separate trees based on a combined analysis of four loci (ITS, LSU, rpb2, tef-1α) were used to delimit species at generic and family levels. Combined with the morphological features, host associations and ecological analyses, acremonium-like species evaluated in the present study are currently assigned to 63 genera, and 14 families in Cephalothecales, Glomerellales and Hypocreales, mainly in the families Bionectriaceae, Plectosphaerellaceae and Sarocladiaceae and five new hypocrealean families, namely Chrysonectriaceae, Neoacremoniaceae, Nothoacremoniaceae, Pseudoniessliaceae and Valsonectriaceae. Among them, 17 new genera and 63 new combinations are proposed, with descriptions of 65 new species. Furthermore, one epitype and one neotype are designated to stabilise the taxonomy and use of older names. Results of this study demonstrated that most species of Acremonium s. lat. grouped in genera of Bionectriaceae, including the type A. alternatum. A phylogenetic backbone tree is provided for Bionectriaceae, in which 183 species are recognised and 39 well-supported genera are resolved, including 10 new genera. Additionally, rpb2 and tef-1α are proposed as potential DNA barcodes for the identification of taxa in Bionectriaceae. Taxonomic novelties: New families: Chrysonectriaceae L.W. Hou, L. Cai & Crous, Neoacremoniaceae L.W. Hou, L. Cai & Crous, Nothoacremoniaceae L.W. Hou, L. Cai & Crous, Pseudoniessliaceae L.W. Hou, L. Cai & Crous, Valsonectriaceae L.W. Hou, L. Cai & Crous. New genera: Bionectriaceae: Alloacremonium L.W. Hou, L. Cai & Crous, Gossypinidium L.W. Hou, L. Cai & Crous, Monohydropisphaera L.W. Hou, L. Cai & Crous, Musananaesporium L.W. Hou, L. Cai & Crous, Paragliomastix L.W. Hou, L. Cai & Crous, Proliferophialis L.W. Hou, L. Cai & Crous, Proxiovicillium L.W. Hou, L. Cai & Crous, Ramosiphorum L.W. Hou, L. Cai & Crous, Verruciconidia L.W. Hou, L. Cai & Crous, Waltergamsia L.W. Hou, L. Cai & Crous; Clavicipitaceae: Subuliphorum L.W. Hou, L. Cai & Crous; Neoacremoniaceae: Neoacremonium L.W. Hou, L. Cai & Crous; Nothoacremoniaceae: Nothoacremonium L.W. Hou, L. Cai & Crous; Plectosphaerellaceae: Allomusicillium L.W. Hou, L. Cai & Crous, Parafuscohypha L.W. Hou, L. Cai & Crous; Pseudoniessliaceae: Pseudoniesslia L.W. Hou, L. Cai & Crous; Sarocladiaceae: Polyphialocladium L.W. Hou, L. Cai & Crous. New species: Bionectriaceae: Alloacremonium ferrugineum L.W. Hou, L. Cai & Crous, Al. humicola L.W. Hou, L. Cai & Crous, Acremonium aerium L.W. Hou, L. Cai & Crous, A. brunneisporum L.W. Hou, L. Cai & Crous, A. chlamydosporium L.W. Hou, L. Cai & Crous, A. ellipsoideum L.W. Hou, Rämä, L. Cai & Crous, A. gamsianum L.W. Hou, L. Cai & Crous, A. longiphialidicum L.W. Hou, L. Cai & Crous, A. multiramosum L.W. Hou, Rämä, L. Cai & Crous, A. mycoparasiticum L.W. Hou, L. Cai & Crous, A. stroudii K. Fletcher, F.C. Küpper & P. van West, A. subulatum L.W. Hou, L. Cai & Crous, A. synnematoferum L.W. Hou, Rämä, L. Cai & Crous, Bulbithecium ammophilae L.W. Hou, L. Cai & Crous, B. ellipsoideum L.W. Hou, L. Cai & Crous, B. truncatum L.W. Hou, L. Cai & Crous, Emericellopsis brunneiguttula L.W. Hou, L. Cai & Crous, Gliomastix musae L.W. Hou, L. Cai & Crous, Gossypinidium sporodochiale L.W. Hou, L. Cai & Crous, Hapsidospora stercoraria L.W. Hou, L. Cai & Crous, H. variabilis L.W. Hou, L. Cai & Crous, Mycocitrus odorus L.W. Hou, L. Cai & Crous, Nectriopsis ellipsoidea L.W. Hou, L. Cai & Crous, Paracylindrocarpon aurantiacum L.W. Hou, L. Cai & Crous, Pn. foliicola Lechat & J. Fourn., Paragliomastix rosea L.W. Hou, L. Cai & Crous, Proliferophialis apiculata L.W. Hou, L. Cai & Crous, Protocreopsis finnmarkica L.W. Hou, L. Cai, Rämä & Crous, Proxiovicillium lepidopterorum L.W. Hou, L. Cai & Crous, Ramosiphorum echinoporiae L.W. Hou, L. Cai & Crous, R. polyporicola L.W. Hou, L. Cai & Crous, R. thailandicum L.W. Hou, L. Cai & Crous, Verruciconidia erythroxyli L.W. Hou, L. Cai & Crous, Ve. infuscata L.W. Hou, L. Cai & Crous, Ve. quercina L.W. Hou, L. Cai & Crous, Ve. siccicapita L.W. Hou, L. Cai & Crous, Ve. unguis L.W. Hou, L. Cai & Crous, Waltergamsia alkalina L.W. Hou, L. Cai & Crous, W. catenata L.W. Hou, L. Cai & Crous, W. moroccensis L.W. Hou, L. Cai & Crous, W. obpyriformis L.W. Hou, L. Cai & Crous; Chrysonectriaceae: Chrysonectria crystallifera L.W. Hou, L. Cai & Crous; Nectriaceae: Xenoacremonium allantoideum L.W. Hou, L. Cai & Crous; Neoacremoniaceae: Neoacremonium distortum L.W. Hou, L. Cai & Crous, N. flavum L.W. Hou, L. Cai & Crous; Nothoacremoniaceae: Nothoacremonium subcylindricum L.W. Hou, L. Cai & Crous, No. vesiculophorum L.W. Hou, L. Cai & Crous; Myrotheciomycetaceae: Trichothecium hongkongense L.W. Hou, L. Cai & Crous; Plectosphaerellaceae: Brunneomyces polyphialidus L.W. Hou, L. Cai & Crous, Parafuscohypha proliferata L.W. Hou, L. Cai & Crous; Sarocladiaceae: Chlamydocillium acaciae L.W. Hou, L. Cai & Crous, C. antarcticum L.W. Hou, L. Cai & Crous, C. guttulatum L.W. Hou, L. Cai & Crous, C. lolii L.W. Hou, L. Cai & Crous, C. soli L.W. Hou, L. Cai & Crous, C. terrestre L.W. Hou, L. Cai & Crous, Parasarocladium chondroidum L.W. Hou, L. Cai & Crous,Polyphialocladium fusisporum L.W. Hou, L. Cai & Crous, Sarocladium agarici L.W. Hou, L. Cai & Crous, S. citri L.W. Hou, L. Cai & Crous, S. ferrugineum L.W. Hou, L. Cai & Crous, S. fuscum L.W. Hou, L. Cai & Crous,S. theobromae L.W. Hou, L. Cai & Crous; Valsonectriaceae: Valsonectria crystalligena L.W. Hou, L. Cai & Crous, V. hilaris L.W. Hou, L. Cai & Crous. New combinations: Bionectriaceae: Acremonium purpurascens (Sukapure & Thirum.) L.W. Hou, L. Cai & Crous, Bulbithecium arxii (Malloch) L.W. Hou, L. Cai & Crous, Bu. borodinense (Tad. Ito et al.) L.W. Hou, L. Cai & Crous, Bu. pinkertoniae (W. Gams) L.W. Hou, L. Cai & Crous, Bu. spinosum (Negroni) L.W. Hou, L. Cai & Crous, Emericellopsis exuviara (Sigler et al.) L.W. Hou, L. Cai & Crous, E. fimetaria (Pers.) L.W. Hou, L. Cai & Crous, E. fuci (Summerb. et al.) L.W. Hou, L. Cai & Crous, E. moniliformis (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, E. salmonea (W. Gams & Lodha) L.W. Hou, L. Cai & Crous, E. tubakii (Gams) L.W. Hou, L. Cai & Crous, Fusariella arenula (Berk. & Broome) L.W. Hou, L. Cai & Crous, Hapsidospora chrysogena (Thirum. & Sukapure) L.W. Hou, L. Cai & Crous, H. flava (W. Gams) L.W. Hou, L. Cai & Crous, H. globosa (Malloch & Cain) L.W. Hou, L. Cai & Crous, H. inversa (Malloch & Cain) L.W. Hou, L. Cai & Crous, Hydropisphaera aurantiaca (C.A. Jørg.) L.W. Hou, L. Cai & Crous, Lasionectria atrorubra (Lechat & J. Fourn.) L.W. Hou, L. Cai & Crous, L. bisepta (W. Gams) L.W. Hou, L. Cai & Crous, L. castaneicola (Lechat & Gardiennet) L.W. Hou, L. Cai & Crous, L. cerealis (P. Karst.) L.W. Hou, L. Cai & Crous, L. olida (W. Gams) L.W. Hou, L. Cai & Crous, Lasionectriopsis dentifera (Samuels) L.W. Hou, L. Cai & Crous, Lasionectriella arenuloides (Samuels) L.W. Hou, L. Cai & Crous, La. marigotensis (Lechat & J. Fourn.) L.W. Hou, L. Cai & Crous, Monohydropisphaera fusigera (Berk. & Broome) L.W. Hou, L. Cai & Crous, Musananaesporium tectonae (R.F. Castañeda) L.W. Hou, L. Cai & Crous, Mycocitrus zonatus (Sawada) L.W. Hou, L. Cai & Crous, Nectriopsis microspora (Jaap) L.W. Hou, L. Cai & Crous, Ovicillium asperulatum (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, O. variecolor (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, Paracylindrocarpon multiloculatum (Samuels) L.W. Hou, L. Cai & Crous, Pn. multiseptatum (Samuels)L.W. Hou, L. Cai & Crous, Paragliomastix chiangraiensis (J.F. Li et al.) L.W. Hou, L. Cai & Crous, Px. luzulae (Fuckel) L.W. Hou, L. Cai & Crous, Px. znieffensis (Lechat & J. Fourn.) L.W. Hou, L. Cai & Crous, Protocreopsis rutila (W. Gams) L.W. Hou, L. Cai & Crous, Proxiovicillium blochii (Matr.)L.W. Hou, L. Cai & Crous, Stanjemonium dichromosporum (Gams & Sivasith.) L.W. Hou, L. Cai & Crous, Verruciconidia persicina (Nicot) L.W. Hou, L. Cai & Crous, Ve. verruculosa (W. Gams & Veenb.-Rijks) L.W. Hou, L. Cai & Crous, Waltergamsia citrina (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. dimorphospora (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. epimycota (Samuels) L.W. Hou, L. Cai & Crous, W. fusidioides (Nicot) L.W. Hou, L. Cai & Crous, W. hennebertii (W. Gams) L.W. Hou, L. Cai & Crous, W. parva (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. pilosa (A. Giraldo et al.) L.W. Hou, L. Cai & Crous, W. zeylanica (Petch) L.W. Hou, L. Cai & Crous; Cephalothecaceae: Phialemonium thermophilum (W. Gams & J. Lacey) L.W. Hou, L. Cai & Crous; Clavicipitaceae: Subuliphorum camptosporum (W. Gams) L.W. Hou, L. Cai & Crous; Coniochaetaceae: Coniochaeta psammospora (W. Gams) L.W. Hou, L. Cai & Crous; Nothoacremoniaceae: Nothoacremonium exiguum (W. Gams) L.W. Hou, L. Cai & Crous; Neoacremoniaceae: Neoacremonium minutisporum (Sukapure & Thirum.) L.W. Hou, L. Cai & Crous; Ne. taiwanense (K.L. Pang et al.) L.W. Hou, L. Cai & Crous; Ne. vitellinum (W. Gams) L.W. Hou, L. Cai & Crous; Plectosphaerellaceae: Allomusicillium domschii (W. Gams) L.W. Hou, L. Cai & Crous, Brunneomyces pseudozeylanicus (W. Gams) L.W. Hou, L. Cai & Crous; Pseudoniessliaceae: Pseudoniesslia minutispora (W. Gams et al.) L.W. Hou, L. Cai & Crous; Sarocladiaceae: Chlamydocillium curvulum (W. Gams) L.W. Hou, L. Cai & Crous, Parasarocladium funiculosum (Sukapure & Thirum.) L.W. Hou, L. Cai & Crous; Valsonectriaceae: Valsonectria inflata (C.H. Dickinson) L.W. Hou, L. Cai & Crous, V. roseola (G. Sm.) L.W. Hou, L. Cai & Crous. Epitype (basionym): Sphaeria violacea J.C. Schmidt ex Fr. Neotype (basionym): Mastigocladium blochii Matr. Citation: Hou LW, Giraldo A, Groenewald JZ, Rämä T, Summerbell RC, Zang P, Cai L, Crous PW (2023). Redisposition of acremonium-like fungi in Hypocreales. Studies in Mycology 105: 23-203. doi: 10.3114/sim.2023.105.02.

Impulsive modelling of rust dynamics and predator releases for biocontrol

Fungal diseases cause serious damages in crop worldwide. In particular, coffee leaf rust (CLR), caused by fungus Hemileia vastatrix attacks coffee leaves and reduces coffee yield. This paper presents a multi-seasonal model of the CLR development in the coffee plantation with continuous dynamics during the rainy season and a discrete event to represent the simpler dynamics during the dry season. Biological control using predators through one or more discrete introduction events over the year is then added. Analytical and semi-numerical studies are performed to identify how much and how frequently predators need to be introduced through the definition of a threshold value, as a function of various parameters. We show that the best strategy to efficiently control the disease depends on the predator mortality: low mortality parasites need be released only once a year, while high mortality parasites should be released more frequently to ensure their persistence in the plantation. This work hence provides qualitative and quantitative bases for the deployment of predator-based biocontrol, a promising alternative to fungicides for rust control.

Characterising the proteomic response of mushroom pathogen Lecanicillium fungicola to Bacillus velezensis QST 713 and Kos biocontrol agents

The fungal pathogen Lecanicillium fungicola causes dry bubble disease in Agaricus bisporus cultivation and affected mushrooms significantly reduce the yield and revenue for mushroom growers. Biocontrol agents may represent an alternative and more environmentally friendly treatment option to help control dry bubble on mushroom farms. Serenade ® is a commercially available biocontrol product used for disease treatment in plant crops. In this work, the in vitro response of L. fungicola to the bacterial strain active in Serenade, Bacillus velezensis (QST 713) and a newly isolated B. velezensis strain (Kos) was assessed. B. velezensis (QST713 and Kos) both produced zones of inhibition on plate cultures of L. fungicola, reduced the mycelium growth in liquid cultures and damaged the morphology and structure of L. fungicola hyphae. The proteomic response of the pathogen against these biocontrol strains was also investigated. Proteins involved in growth and translation such as 60S ribosomal protein L21-A (-32-fold) and 40S ribosomal protein S30 (-17-fold) were reduced in abundance in B. velezensis QST 713 treated samples, while proteins involved in a stress response were increased (norsolorinic acid reductase B (47-fold), isocitrate lyase (11-fold) and isovaleryl-CoA dehydrogenase (8-fold). L. fungicola was found to have a similar proteomic response when exposed to B. velezensis (Kos). This work provides information on the response of L. fungicola to B. velezensis (QST 713) and indicates the potential of B. velezensis Kos as a novel biocontrol agent.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10658-022-02482-1.

Ascomycetes from the Qilian Mountains, China - Hypocreales

To investigate fungi from the Qilian Mountains in Gansu Province, ascomycetous specimens were collected and hypocrealean fungi were examined. Eighteen species belonging to six genera in the families Hypocreaceae and Nectriaceae were identified, including 11 species of Hypomyces and Trichoderma in Hypocreaceae and seven species of Nectria, Stylonectria, Thelonectria, and Thyronectria in Nectriaceae. Among them, Stylonectria qilianshanensis and Trichoderma gansuanum are new to science. DNA sequence analyses of combined ACL1, ITS, RPB2, and TEF1 regions confirmed their taxonomic placements. Morphological distinctions between the new species and their close relatives are discussed. Hypomyces tremellicola is reported for the first time in China.

Taxonomy of the Sphaerostilbella broomeana-group (Hypocreales, Ascomycota)

Three new species, closely related to Sphaerostilbella broomeana, are described from the USA and India. These species form septate conidia from simple conidiophores with individual branches terminating in a single phialide and chlamydospores. Teleomorphs, known for S. broomeana and S. appalachiensis, are characterised by hairy perithecia and fusiform, apiculate, and conspicuously warted ascospores. This combination of characters distinguishes the S. broomeana-group from other members of Sphaerostilbella that all form gliocladium-type anamorphs and mostly grow on basidiomata of Stereum spp. Like in other species of the genus, the majority of hosts of the species described in this paper belong to wood-inhabiting taxa of Russulales. Sphaerostilbella broomeana had been recorded from a few regions in Europe and exclusively on Heterobasidion annosum. Herein, it is reported also from H. parviporum in many other localities and on H. insulare s.l. at the foothills of the Himalayas. Its sister species, found in the same region in northern India on another member of Russulales (Dichostereum effuscatum), is described as S. himalayensis. The two species described from North America colonize polypores from various taxa. Whereas S. appalachiensis occurs in eastern USA, with H. irregulare among its hosts, S. toxica is so far known only from two locations in eastern Texas, growing on Gloeophyllum striatum (Polyporales). Despite their great similarity in morphology and ITS rDNA, TEF1 sequences clearly distinguish these two North-American species. Moreover, the two strains of S. toxica appeared metabolically distinct as their organic extracts strongly inhibited the growth of human pathogenic microbes grown in vitro. Phylogenetic analysis of rDNA sequences supports monophyly of the genus Sphaerostilbella and the included S. broomeana-group, established here.

Verticillium systematics and evolution: how confusion impedes Verticillium wilt management and how to resolve it

Verticillium wilts are important vascular wilt diseases that affect many crops and ornamentals in different regions of the world. Verticillium wilts are caused by members of the ascomycete genus Verticillium, a small group of 10 species that are related to the agents of anthracnose caused by Colletotrichum species. Verticillium has a long and complicated taxonomic history with controversies about species boundaries and long overlooked cryptic species, which confused and limited our knowledge of the biology of individual species. We first review the taxonomic history of Verticillium, provide an update and explanation of the current system of classification and compile host range and geographic distribution data for individual species from internal transcribed spacer (ITS) GenBank records. Using Verticillium as an example, we show that species names are a poor vehicle for archiving and retrieving information, and that species identifications should always be backed up by DNA sequence data and DNA extracts that are made publicly available. If such a system were made a prerequisite for publication, all species identifications could be evaluated retroactively, and our knowledge of the biology of individual species would be immune from taxonomic changes, controversy and misidentification. Adoption of this system would improve quarantine practices and the management of diseases caused by various plant pathogens.

Delimitation of Neonectria and Cylindrocarpon (Nectriaceae, Hypocreales, Ascomycota) and related genera with Cylindrocarpon-like anamorphs

Neonectria is a cosmopolitan genus and it is, in part, defined by its link to the anamorph genus Cylindrocarpon. Neonectria has been divided into informal groups on the basis of combined morphology of anamorph and teleomorph. Previously, Cylindrocarpon was divided into four groups defined by presence or absence of microconidia and chlamydospores. Molecular phylogenetic analyses have indicated that Neonectriasensu stricto and Cylindrocarponsensu stricto are phylogenetically congeneric. In addition, morphological and molecular data accumulated over several years have indicated that Neonectria sensu lato and Cylindrocarponsensu lato do not form a monophyletic group and that the respective informal groups may represent distinct genera. In the present work, a multilocus analysis (act, ITS, LSU, rpb1, tef1, tub) was applied to representatives of the informal groups to determine their level of phylogenetic support as a first step towards taxonomic revision of Neonectriasensu lato. Results show five distinct highly supported clades that correspond to some extent with the informal Neonectria and Cylindrocarpon groups that are here recognised as genera: (1) N. coccinea-group and Cylindrocarpon groups 1 & 4 (Neonectria/Cylindrocarponsensu stricto); (2) N.rugulosa-group (Rugonectria gen. nov.); (3) N. mammoidea/N. veuillotiana-groups and Cylindrocarpon group 2 (Thelonectria gen. nov.); (4) N. radicicola-group and Cylindrocarpon group 3 (Ilyonectria gen. nov.); and (5) anamorph genus Campylocarpon. Characteristics of the anamorphs and teleomorphs correlate with the five genera, three of which are newly described. New combinations are made for species where their classification is confirmed by phylogenetic data.

An overview of the taxonomy, phylogeny, and typification of nectriaceous fungi in Cosmospora, Acremonium, Fusarium, Stilbella, and Volutella

A comprehensive phylogenetic reassessment of the ascomycete genus Cosmospora (Hypocreales, Nectriaceae) is undertaken using fresh isolates and historical strains, sequences of two protein encoding genes, the second largest subunit of RNA polymerase II (rpb2), and a new phylogenetic marker, the larger subunit of ATP citrate lyase (acl1). The result is an extensive revision of taxonomic concepts, typification, and nomenclatural details of many anamorph- and teleomorph-typified genera of the Nectriaceae, most notably Cosmospora and Fusarium. The combined phylogenetic analysis shows that the present concept of Fusarium is not monophyletic and that the genus divides into two large groups, one basal in the family, the other terminal, separated by a large group of species classified in genera such as Calonectria, Neonectria, and Volutella. All accepted genera received high statistical support in the phylogenetic analyses. Preliminary polythetic morphological descriptions are presented for each genus, providing details of perithecia, micro- and/or macro-conidial synanamorphs, cultural characters, and ecological traits. Eight species are included in our restricted concept of Cosmospora, two of which have previously documented teleomorphs and all of which have Acremonium-like microconidial anamorphs. A key is provided to the three anamorphic species recognised in Atractium, which is removed from synonymy with Fusarium and epitypified for two macroconidial synnematous species and one sporodochial species associated with waterlogged wood. Dialonectria is recognised as distinct from Cosmospora and two species with teleomorph, macroconidia and microconidia are accepted, including the new species D. ullevolea. Seven species, one with a known teleomorph, are classified in Fusicolla, formerly considered a synonym of Fusarium including members of the F. aquaeductuum and F. merismoides species complex, with several former varieties raised to species rank. Originally a section of Nectria, Macroconia is raised to generic rank for five species, all producing a teleomorph and macroconidial anamorph. A new species of the Verticillium-like anamorphic genus Mariannaea is described as M. samuelsii. Microcera is recognised as distinct from Fusarium and a key is included for four macroconidial species, that are usually parasites of scale insects, two of them with teleomorphs. The four accepted species of Stylonectria each produce a teleomorph and micro- and macroconidial synanamorphs. The Volutella species sampled fall into three clades. Pseudonectria is accepted for a perithecial and sporodochial species that occurs on Buxus. Volutella s. str. also includes perithecial and/or sporodochial species and is revised to include a synnematous species formerly included in Stilbella. The third Volutella-like clade remains unnamed. All fungi in this paper are named using a single name system that gives priority to the oldest generic names and species epithets, irrespective of whether they are originally based on anamorph or teleomorph structures. The rationale behind this is discussed.

Lecanicillium fungicola: causal agent of dry bubble disease in white-button mushroom

Lecanicillium fungicola causes dry bubble disease in commercially cultivated mushroom. This review summarizes current knowledge on the biology of the pathogen and the interaction between the pathogen and its most important host, the white-button mushroom, Agaricus bisporus. The ecology of the pathogen is discussed with emphasis on host range, dispersal and primary source of infection. In addition, current knowledge on mushroom defence mechanisms is reviewed.

TAXONOMY

Lecanicillium fungicola (Preuss) Zare and Gams: Kingdom Fungi; Phylum Ascomycota; Subphylum Pezizomycotina; Class Sordariomycetes; Subclass Hypocreales; Order Hypocreomycetidae; Family Cordycipitaceae; genus Lecanicillium.

HOST RANGE

Agaricus bisporus, Agaricus bitorquis and Pleurotus ostreatus. Although its pathogenicity for other species has not been established, it has been isolated from numerous other basidiomycetes.

DISEASE SYMPTOMS

Disease symptoms vary from small necrotic lesions on the caps of the fruiting bodies to partially deformed fruiting bodies, called stipe blow-out, or totally deformed and undifferentiated masses of mushroom tissue, called dry bubble. The disease symptoms and severity depend on the time point of infection. Small necrotic lesions result from late infections on the fruiting bodies, whereas stipe blow-out and dry bubble are the result of interactions between the pathogen and the host in the casing layer.

ECONOMIC IMPORTANCE

Lecanicillium fungicola is a devastating pathogen in the mushroom industry and causes significant losses in the commercial production of its main host, Agaricus bisporus. Annual costs for mushroom growers are estimated at 2-4% of total revenue. Reports on the disease originate mainly from North America and Europe. Although China is the main producer of white-button mushrooms in the world, little is known in the international literature about the impact of dry bubble disease in this region.

CONTROL

The control of L. fungicola relies on strict hygiene and the use of fungicides. Few chemicals can be used for the control of dry bubble because the host is also sensitive to fungicides. Notably, the development of resistance of L. fungicola has been reported against the fungicides that are used to control dry bubble disease. In addition, some of these fungicides may be banned in the near future.

USEFUL WEBSITES

http://www.mycobank.org; http://www.isms.biz; http://www.cbs.knaw.nl.

Mitochondrial gene sequences alone or combined with ITS region sequences provide firm molecular criteria for the classification of Lecanicillium species

The recent revision of Verticillium sect. Prostrata led to the introduction of the genus Lecanicillium, which comprises the majority of the entomopathogenic strains. Sixty-five strains previously classified as Verticillium lecanii or Verticillium sp. from different geographical regions and hosts were examined and their phylogenetic relationships were determined using sequences from three mitochondrial (mt) genes [the small rRNA subunit (rns), the NADH dehydrogenase subunits 1 (nad1) and 3 (nad3)] and the ITS region. In general, single gene phylogenetic trees differentiated and placed the strains examined in well-supported (by BS analysis) groups of L. lecanii, L. longisporum, L. muscarium, and L. nodulosum, although in some cases a few uncertainties still remained. nad1 was the most informative single gene in phylogenetic analyses and was also found to contain group I introns with putative open reading frames (ORFs) encoding for GIY-YIG endonucleases. The combined use of mt gene sequences resolved taxonomic uncertainties arisen from ITS analysis and, alone or in combination with ITS sequences, helped in placing uncharacterised Verticillium lecanii and Verticillium sp. firmly into Lecanicillium species. Combined gene data from all the mt genes and all the mt genes and the ITS region together, were very similar. Furthermore, a relaxed correlation with host specificity -- at least for Homoptera -- was indicated for the rns and the combined mt gene sequences. Thus, the usefulness of mt gene sequences as a convenient molecular tool in phylogenetic studies of entomopathogenic fungi was demonstrated.

Fungicide sensitivity of selected Verticillium fungicola isolates from Agaricus bisporus farms

Five isolates of Verticillium fungicola, isolated from diseased fruiting bodies of Agaricus bisporus collected from mushroom farms in Serbia during 2002-2003, were studied. By observing their colony morphology under different growth conditions and their pathogenic characteristics, the isolates were identified as V. fungicola var. fungicola. The peat/lime casing was the primary source of infection. Testing of sensitivity to selected fungicides showed that all isolates were highly resistant to benomyl (EC50 values were higher than 200.00 mg/l), moderately sensitive to iprodione (EC50 values were between 11.93 and 22.80 mg/l), and highly sensitive to prochloraz-Mn (EC50 values were less than 3.00 mg/l).

Phylogenetic evidence for an animal pathogen origin of ergot and the grass endophytes

Grass-associated fungi (grass symbionts) in the family Clavicipitaceae (Ascomycota, Hypocreales) are species whose host range is restricted to the plant family Poaceae and rarely Cyperaceae. The best-characterized species include Claviceps purpurea (ergot of rye) and Neotyphodium coenophialum (endophyte of tall fescue). They have been the focus of considerable research due to their importance in agricultural and grassland ecosystems and the diversity of their bioactive secondary metabolites. Here we show through multigene phylogenetic analyses and ancestral character state reconstruction that the grass symbionts in Clavicipitaceae are a derived group that originated from an animal pathogen through a dynamic process of interkingdom host jumping. The closest relatives of the grass symbionts include the genera Hypocrella, a pathogen of scale insects and white flies, and Metarhizium, a generalist arthropod pathogen. These data do not support the monophyly of Clavicipitaceae, but place it as part of a larger clade that includes Hypocreaceae, a family that contains mainly parasites of other fungi. A minimum of 5-8 independent and unidirectional interkingdom host jumps has occurred among clavicipitaceous fungi, including 3-5 to fungi, 1-2 to animals, and 1 to plants. These findings provide a new evolutionary context for studying the biology of the grass symbionts, their role in plant ecology, and the evolution of host affiliation in fungal symbioses.

Molecular and immunochemical phylogeny of Verticillium species

21 strains with all typical morphological characteristics of eight Verticillium species (Phyllachorales) were studied in this work, together with representatives from four Hypocreales species (11 strains), that were previously classified as members of the genus. The PCR products from two nuclear genes, i.e. the ITS1-5.8S-ITS2 region and RNA polymerase II largest subunit gene (rpb1), together with four mitochondrial genes, i.e. the small ribosomal rRNA subunit (rns), the two NADH dehydrogenase subunit genes (nad1 and nad3), and the cytochrome oxidase subunit III gene (cox3) were sequenced and analyzed. Similarly, antibodies raised against one strain of each of the species examined (V. nubilum and V. theobromae excluded) were used against the proteins of all other strains. The number and relative area of precipitates formed after crossed electrophoreses served to estimate the degree of immunochemical relatedness. Combined molecular and immunochemical data clarified the phylogenetic relationships of all true Verticillium species and provided a convincing insight into the evolutionary relation of the sect. Nigrescentia with members of the sect. Verticillium and sect. Prostrata that until recently were included in Verticillium.

Compatibility of the entomopathogenic fungus Lecanicillium muscarium and insecticides for eradication of sweetpotato whitefly, Bemisia tabaci

The compatibility of the entomopathogenic fungus Lecanicillium muscarium and chemical insecticides used to control the second instar stages of the sweetpotato whitefly, Bemisia tabaci, was investigated. The effect on spore germination of direct exposure for 24 h to the insecticides imidacloprid, buprofezin, teflubenzuron and nicotine was determined. Only exposure to buprofezin was followed by acceptable spore germination. However, all chemicals significantly reduced spore germination when compared to a water control. Infectivity of L. muscarium in the presence of dry residues of buprofezin, teflubenzuron and nicotine (imidacloprid is a systemic pesticide) on foliage were also investigated. No significant detrimental effects on the level of control of B. tabaci was recorded when compared with fungi applied to residue free foliage on either tomato or verbena plants. Fungi in combination with imidacloprid gave higher B. tabaci mortality on verbena foliage compared to either teflubenzuron or nicotine and fungi combinations. Use of these chemical insecticides with L. muscarium in integrated control programmes for B. tabaci is discussed.

Reduced sensitivity of the mushroom pathogen Verticillium fungicola to prochloraz-manganese in vitro

105 isolates of Verticillium fungicola from Spanish mushroom crops collected between 1992 and 1999 were tested in vitro for their sensitivities to prochloraz-manganese. Dose response relationships for inhibition of mycelial growth by the fungicide were assessed in radial growth experiments on fungicide-amended malt extract agar. The ED50 values recorded for all 105 isolates studied ranged between 0.8 ppm in 1992 and 8.8 in 1998, with an average of 2.9. 86% of the isolates tested were more sensitive to prochloraz-manganese and had ED50 values below 5 ppm, while the other 14% were slightly tolerant with ED50 values equal or above 5 ppm. Of those tested from 1999, 60% (21 isolates) grew with 50 ppm and 40% (14) also at 100 ppm, although mycelial growth was inhibited at least by 82 and 87%, respectively. The resistance factor calculated ranged from low fungicide resistance (RF=3.0) in 1992 to moderate resistance (RF=12.6) in 1998. These data confirm that the sensitivity of V. fungicola to the prochloraz-manganese gradually diminishes.

The type species of Verticillium is not congeneric with the plant-pathogenic species placed in Verticillium and it is not the anamorph of 'Nectria' inventa

The monotype species of the genus Verticillium, Verticillium tenerum, is a synonym of the older name Sporotrichum luteo-album. Its purported teleomorph connection with 'Nectria' inventa is refuted and the preserved specimens of that species are considered as probably identical with Stephanonectria keithii (Bionectriaceae). V. luteo-album takes a unique position in the Glomerella clade of ascomycetes, as sister of the Verticillium-Plectosphaerella clade, which comprises plant-pathogenic species. V. luteo-album is not closely related to V. dahliae and its relatives, which are also situated in this clade. Conservation of the name Verticillium with V. dahliae as conserved type will be necessary to retain this generic name for the plant-pathogenic Verticillium species. In anticipation of this conservation, the new combination Acrostalagmus luteo-albus (syn. Sporotrichum luteo-album) is made.

Plant pathogenic Verticillium species: how many of them are there?

SUMMARY Two of the currently widely accepted species in the section Nigrescentia of the genus Verticillium are major plant pathogens inducing wilt diseases in a wide range of mainly dicotyledonous hosts. Three species closely related to these two are less important wilt pathogens and soil saprophytes. A sixth species, V. theobromae, causes the cigar end of banana. Molecular and genetic studies have shown that these species represent a complex pool of discrete lineages of varying degrees of relatedness with unknown levels of gene flow between them. Most isolates are haploid, but some are thought to be amphihaploid interspecific hybrids. Until our understanding of this complex is much improved, it seems most appropriate to add only one new species, for wilt isolates primarily associated with potato and producing dark-resting-mycelium in bundles (currently known as V. albo-atrum Grp2). It is suggested that the following be retained: (i) V. dahliae to include all isolates which produce only microsclerotia, (ii) V. albo-atrum to cover the majority of isolates producing only dark-resting-mycelium (and not in bundles), and (iii) V. nigrescens, V. nubilum, V. tricorpus and V. theobromae for the minor wilt pathogens/saprophytes and the non-wilt pathogen.

Molecular Phylogenetic Analyses of Verticillium fungicola and Related Species Causing Dry Bubble Disease of the Cultivated Button Mushroom, Agaricus bisporus

ABSTRACT Molecular phylogenetic analyses were performed on 40 isolates of Verticillium fungicola collected from various Pennsylvania mushroom farms in 1999 and 28 isolates of Verticillium spp. collected during the last 50 years from various geographic locations. Sequence analysis of internal transcribed spacers 1 and 2 (ITS1 and ITS2) and 5.8S regions of the nuclear ribosomal DNA (rDNA) transcriptional unit and analysis of random amplified polymorphic DNA (RAPD) data were performed for the 68 isolates of Verticillium spp. Identical rDNA sequences were obtained for all 40 Pennsylvania isolates collected during 1999, 13 North American isolates collected during the last 50 years, and the ex-type strain of V. fungicola var. aleophilum. Sequence analysis of European isolates revealed a close relationship to the ex-type strain V. fungicola var. fungicola. No European-like isolates of V. fungicola var. fungicola were detected in the collection of North American isolates examined. Results from six decamer RAPD primers strongly indicate the presence of a clonal population of V. fungicola among Pennsylvania isolates. In addition, RAPD data delineated a Korean isolate (DC130) and ex-type strain V. fungicola var. aleophilum from the North American group. Virulence assays, based on spore inoculation of mushroom pilei, revealed variation corresponding to each neighbor-joining and RAPD grouping. All isolates with rDNA sequence and RAPD grouping similarity to ex-type strains V. fungicola var. aleophilum and V. fungicola var. fungicola displayed the highest level of virulence. Based on rDNA sequence and RAPD analyses, isolates displaying reduced or no virulence were distantly related to these two varieties. All results obtained for the analyses of ex-type strain V. fungicola var. flavidum suggested that this fungal isolate should not be considered a variety of V. fungicola, but rather a distinct species.

Extracellular hydrolytic enzymes in the fungal genus Verticillium: adaptations for pathogenesis

The insect and plant pathogens within the fungal genus Verticillium showed enzymatic adaptation (production and regulation) directed to the degradation of some of the polymers found in the integument of their respective hosts. For example, the facultative plant pathogens (V. albo-atrum and V. dahliae) produced greater levels of cellulase and xylanase than the facultative insect pathogen (V. lecanii). Verticillium lecanii produced extracellular subtilisin-like protease when grown in insect cuticle medium but not in plant cell wall medium, while the plant pathogen V. albo-atrum showed a diminished regulatory component in the production of this enzyme. The opportunistic pathogens (V. fungicola and V. coccosporum) and the saprobic species (V. rexianum) were less specific in the production and regulation of several proteases as well as cellulases and xylanases. A dendrogram based on cluster analysis compiled from fungal API-ZYM profiles showed commonalties in a broad array of extracellular enzymes within a host-pathogen group (i.e. insect or plant pathogen). The opportunistic pathogens were dispersed throughout the dendrogram, suggestive of the diversity in type and expression of extracellular enzymes.Key words: extracellular enzymes, pathogenic fungi.

Taxonomic status of putative Verticillum alboatrum isolates

Two fungal isolates, formerly classified as Verticillium alboatrum and proposed as forming the basis of a new sub-group ('Group 2') within the species, have been shown to be non-pathogenic to known hosts of V. alboatrum and, on the basis of molecular evidence, to be closely related to Verticillium psalliotae and Verticillium fungicola. We propose that the taxon V. alboatrum be confined to those closely related isolates, usually plant pathogenic and usually producing dark resting mycelium, referred to by other authors as Group 1. The only sub-specific groupings which appear valid (based on pathological and molecular evidence) comprise: (1) host-adapted isolates from lucerne; and (2) all other isolates.

How natural should anamorph genera be?

The taxonomy of anamorphic fungi has always been artificial, as a concession to the practical needs of identifying and naming important organisms, because of insufficient characters indicative of a more natural classification. Integration of anamorph taxa into a teleomorph classification is best served by retaining anamorph names for fungi that have no teleomorph fructification. Proposals to split more or less heterogeneous anamorph genera such as Aspergillus, Fusarium, Acremonium, Verticillium, and Gliocladium into more natural units have prompted this assay. While subdivision of these genera can be defended only partly, some nematophagous genera with affinities to Arthrobotrys or Monacrosporium are considered for lumping, to achieve a more natural classification. This raises the question of to what extent anamorph genera can be delimited naturally and how far they must reflect teleomorph associations. A consistent application of natural genus concepts for anamorphic fungi, even if that were possible, would completely upset nomenclature. While the segregation of morphologically divergent, obviously unrelated taxa from an anamorph genus is defendable, some admittedly deviating taxa (different teleomorphs) should be tolerated in somewhat artificial genera for the sake of identification. Conversely, lumping all anamorphs associated with one teleomorph genus into one genus is not supported when the criteria used for identification clearly favour splitting; otherwise it would render identification according to morphological criteria impossible. Therefore classification of anamorph genera cannot aim at genera that adequately reflect natural relationships and the most convenient generic delimitation must be considered for individual cases. Key words: anamorph, teleomorph, classification, nomenclature, Deuteromycetes, pleomorphism.