Mycoparasitic Species Research Articles

Diversity of mycoparasitic Pythium sensu stricto and Globisporangium species in West Azarbaijan province of Iran

AbstractPythium sensu stricto (s.s.) and Globisporangium species are important components of the soil microbial community and exhibit diverse lifestyles, including mycoparasitism. However, a comprehensive understanding of the species diversity of these mycoparasites in the West Azarbaijan province of Iran is lacking. In this study, a total of 114 mycoparasitic Pythium s.s. and Globisporangium isolates were obtained from agricultural soils collected from six regions in the province. Through DNA barcoding, all Globisporangium isolates were identified as G. nunn, while the barcode markers were insufficient to accurately resolve species boundaries in Pythium s.s. By combining morphological and multilocus sequence data, five species within the genus Pythium s.s. were identified: P. salmasense sp. nov., a potentially new species, and three known species, P. acanthicum, P. ornamentatum, and P. periplocum. Pythium ornamentatum was the most common species and found in all regions studied, followed by G. nunn and P. acanthicum, which were both isolated from four regions. While the isolates of G. nunn showed no mycoparasitic activity against Sclerotinia sclerotiorum, all Pythium s.s. species were capable of infecting the hyphae of this pathogen. The existence of mycoparasitic species is promising for biological control of soil‐borne fungal pathogens in the province. The widespread occurrence of P. ornamentatum, G. nunn, and P. acanthicum may suggest their adaptation to local soil and environmental conditions, indicating their potentially superior effectiveness in controlling plant diseases across different regions if used as biocontrol agents.

Antagonistic activities of mycoparasitic Pythium species against Fusarium oxysporum f. sp. lycopersici and Botrytis cinerea on tomatoes

In this study, antagonistic effects of Pythium acanthophoron, P. lycopersicum, P. oligandrum and P. paroecandrum against Fusarium oxysporum f. sp. lycopersici and Botrytis cinerea were investigated by in vitro and in vivo trials. In vitro mycoparasitic activities of Pythium species were determined by dual culture, inverted plate culture and agar diffusion tests. As a result of dual culture tests, suppressive effects of all mycoparasites were over 70% against mycelial growth of the pathogens. Inverted plate tests showed that antagonistic effects of mycoparasites regarding their volatile compounds were rather low. In the agar diffusion test, all mycoparasites showed antibiosis effect, however P. lycopersicum had the highest suppressive effect on both pathogens. In pot trials, mycoparasites were effective to protect tomato seedlings when pathogens were seperately inoculated, and suppressed the symptoms. When two pathogens were inoculated together, P. paroecandrum was ineffective against B. cinerea, but decreased the severity of wilt symptoms, while other mycoparasites totally inhibited both diseases. Chromatographic analyses made by using leaf samples taken 12, 24, 48 and 72 hours after pathogen inoculation showed meaningful increase on chlorogenic acid, caffeic acid and epicatechine, in the samples taken 48 hours after inoculation. Analyses after the inoculations of tomatoes with the mycoparasites and/or pathogens showed that mycoparasites also caused increase in the amounts of phenolics. This indicated that the mycoparasites could be effective to induce defense mechanisms of tomato plants against pathogens. Among them, P. oligandrum can be mentioned as the most effective mycoparasite regarding the induction of phenolics.

New treasures in Cordycipitaceae: Fungicolous fungi associated with Pseudocercospora fijiensis and P. musae in Brazil, including Matutinistella gen. nov.

Cordycipitaceae is a large family belonging to the order Hypocreales, including cosmopolitan species found on different substrates. This family includes species with different lifestyles such as entomopathogenic, endophytic, and mycoparasitic fungi. Some mycoparasitic species in this family attack phytopathogenic fungi. We identified species of Cordycipitaceae found during a survey of fungicolous fungi associated with Pseudocercospora fijiensis and P. musae in Brazil. Based on morphological characters combined with phylogenetic analysis of ITS, LSU, SSU, RPB1, RPB2, and TEF1-α, we propose a new genus in Cordycipitaceae, namely Matutinistella, with its type species M. brasiliensis, and a new species of the genus Simplicillium, namely S. pseudocercosporicola. Furthermore, we report P. fijiensis as a new host of the mycoparasitic fungus Simplicillium lanosoniveum. In this study we newly report fungicolous fungi of Cordycipitaceae associated with the causal agents of Black Sigatoka and Yellow Sigatoka on banana crops. We provide relevant information for future work involving control measures for these diseases that cause major losses in banana crops.

New mycoparasitic species in the genera Niveomyces and Pseudoniveomycesgen. nov. (Hypocreales: Cordycipitaceae), with sporothrix-like asexual morphs, from Thailand.

Four new species of the genus Niveomyces are described from Thailand. They were found as mycoparasites on: Ophiocordyceps infecting flies (Diptera) for Niveomyces albus; ants (Hymenoptera) for N. formicidarum; and leafhoppers (Hemiptera) for N. hirsutellae and N. multisynnematus. A new genus, Pseudoniveomyces with two species: Pseudoniveo. blattae (type species), parasitic on Ophiocordyceps infecting cockroaches, and Pseudoniveo. arachnovorum, found on a spider egg sac, are also described. These fungi share a common feature which is a sporothrix-like asexual morph. Based on our molecular data, Sporothrix insectorum is shown to be affiliated to the genus Niveomyces, and thus a new combination N. insectorum comb. nov. is proposed. Niveomyces coronatus, N. formicidarum and N. insectorum formed the N. coronatus species complex found on ant-pathogenic Ophiocordyceps from different continents. Pseudoniveomyces species are distinguished from Niveomyces spp. based on the presence of fusoid macroconidia in culture and a red pigment diffused in the medium, resembling to Gibellula and Hevansia. The molecular phylogenetic analyses also confirmed its generic status. The host/substrates associated with the genera within Cordycipitaceae were mapped onto the phylogeny to demonstrate that mycoparasitism also evolved independently multiple times in this family. Citation: Kobmoo N, Tasanathai K, Araújo JPM, Noisripoom W, Thanakitpipattana D, Mongkolsamrit S, Himaman W, Houbraken J, Luangsa-ard JJ (2023). New mycoparasitic species in the genera Niveomyces and Pseudoniveomyces gen. nov. (Hypocreales: Cordycipitaceae), with sporothrix-like asexual morphs, from Thailand. Fungal Systematics and Evolution 12: 91-110. doi: 10.3114/fuse.2023.12.07.

Phylogenetic conservatism of mycoparasitism and its contribution to pathogen antagonism.

Closely related species are expected to have similar functional traits due to shared ancestry and phylogenetic inertia. However, few tests of this hypothesis are available for plant-associated fungal symbionts. Fungal leaf endophytes occur in all land plants and can protect their host plant from disease by a variety of mechanisms, including by parasitizing pathogens (e.g., mycoparasitism). Here, we tested whether phylogenetic relatedness among species of Cladosporium, a widespread genus that includes mycoparasitic species, predicts the effect of this endophyte on the severity of leaf rust disease. First, we used congruence among different marker sequences (i.e., genealogical concordance phylogenetic species recognition criterion) to delimit species of Cladosporium. Next, in a controlled experiment, we quantified both mycoparasitism and disease modification for the selected Cladosporium species. We identified 17species of Cladosporium; all the species reduced rust disease severity in our experiment. Cladosporium phylogeny was a significant predictor of mycoparasitism. However, we did not observe a phylogenetic effect on disease severity overall, indicating that other mechanism/s operating independently of shared ancestry also contributed to endophyte effects on disease severity. Indeed, a second experiment showed that Cladosporium endophyte exudates (no live organism) from divergent species groups equally reduced disease severity. Our results reveal that multiple mechanisms contribute to the protective effects of an endophyte against a plant pathogen, but not all traits underlying these mechanisms are phylogenetically conserved.

Network Analysis Reveals Different Cellulose Degradation Strategies Across Trichoderma harzianum Strains Associated With XYR1 and CRE1.

Trichoderma harzianum, whose gene expression is tightly controlled by the transcription factors (TFs) XYR1 and CRE1, is a potential candidate for hydrolytic enzyme production. Here, we performed a network analysis of T. harzianum IOC-3844 and T. harzianum CBMAI-0179 to explore how the regulation of these TFs varies between these strains. In addition, we explored the evolutionary relationships of XYR1 and CRE1 protein sequences among Trichoderma spp. The results of the T. harzianum strains were compared with those of Trichoderma atroviride CBMAI-0020, a mycoparasitic species. Although transcripts encoding carbohydrate-active enzymes (CAZymes), TFs, transporters, and proteins with unknown functions were coexpressed with cre1 or xyr1, other proteins indirectly related to cellulose degradation were identified. The enriched GO terms describing the transcripts of these groups differed across all strains, and several metabolic pathways with high similarity between both regulators but strain-specific differences were identified. In addition, the CRE1 and XYR1 subnetworks presented different topology profiles in each strain, likely indicating differences in the influences of these regulators according to the fungi. The hubs of the cre1 and xyr1 groups included transcripts not yet characterized or described as being related to cellulose degradation. The first-neighbor analyses confirmed the results of the profile of the coexpressed transcripts in cre1 and xyr1. The analyses of the shortest paths revealed that CAZymes upregulated under cellulose degradation conditions are most closely related to both regulators, and new targets between such signaling pathways were discovered. Although the evaluated T. harzianum strains are phylogenetically close and their amino acid sequences related to XYR1 and CRE1 are very similar, the set of transcripts related to xyr1 and cre1 differed, suggesting that each T. harzianum strain used a specific regulation strategy for cellulose degradation. More interestingly, our findings may suggest that XYR1 and CRE1 indirectly regulate genes encoding proteins related to cellulose degradation in the evaluated T. harzianum strains. An improved understanding of the basic biology of fungi during the cellulose degradation process can contribute to the use of their enzymes in several biotechnological applications and pave the way for further studies on the differences across strains of the same species.

Cryptococcus depauperatus, a close relative of the human-pathogen C. neoformans, associated with coffee leaf rust (Hemileia vastatrix) in Cameroon.

The genus Cryptococcus is well known for its two species -Cryptococcus neoformans and C. gatii-that are etiological agents of cryptococcosis,an important fungal disease of mammals, including humans, and which is particularly common in immunocompromised patients. Nevertheless, Cryptococcus is a large and widely distributed genus of basidiomycetes occupying a broad range of niches, including mycoparasitism. One such mycoparasitic species is Cryptococcus depauperatus, which was firstly mistakenly described as a pathogen of scale insects under the name Aspergillus depauperatus. The "Aspergillus" conidiophores were later shown to be basidia of a Cryptococcus and the new combination C. depauperatus was proposed. Additionally, instead of an entomopathogen, the fungus was found to be a mycoparasite growing on the entomopathogen Akanthomyces (Lecanicillium) lecanii. Recently, during surveys for mycoparasites of coffee leaf rust (Hemileia vastatrix) in the context of a biocontrol project, white colonies covering rust pustules were observed in Cameroon. Upon close examination, instead of a member of the "white colony forming complex" of Ascomycetes, commonly collected growing on H. vastatrix, such colonies were found to represent a basidiomycete fungus with basidia-bearing chains of basidiospores, typical of the genus Cryptococcus. Morphological and molecular evidence was generated supporting the identification of the fungus on rust pustules as C. depauperatus. This is the first record of C. depauperatus from Africa and of its association with coffee leaf rust.

Isolation frequency and efficiency of mycoparasitic Pythium species in the West Mediterranean region of Turkey

• Besides significant plant pathogens, there are mycoparasitic species in the genus Pythium. • Surface soil dilution plate method is the most suitable method for the isolation of mycoparasitic Pythium species. • Mycoparasitic Pythium species are common in cultivated soils, especially in sugarbeet areas. • Mycoparasitic Pythium species may be used as biocontrol agents against soilborne fungal plant pathogens. A total of 132 mycoparasitic Pythium isolates were obtained from the soil samples taken from fruit orchards, vegetable fields, carnation greenhouses, sugarbeet fields and cereal fields in the West Mediterranean region of Turkey. The Oomycetes were isolated by using; surface soil dilution plate, sclerotia bait and precolonised plate methods. Isolates were identified as P. acanthophoron , P. amasculinum , P. lycopersicum , P. oligandrum , P. periplocum and P. paroecandrum , according to their morphological and molecular characteristics. The most commonly isolated mycoparasitic species were P. amasculinum and P. lycopersicum . The majority of the mycoparasites came from soil samples taken from the sugarbeet growing areas. It was determined that all isolates showed high mycoparasitic activity against Botrytis cinerea and Rhizoctonia solani , however Sclerotinia rolfsii was resistant. It can be concluded that the mycoparasitic Pythium species can be used as biocontrol agents against B. cinerea and R. solani .

Horizontal Gene Transfer and Tandem Duplication Shape the Unique CAZyme Complement of the Mycoparasitic Oomycetes Pythium oligandrum and Pythium periplocum.

Crop protection strategies that are effective but that reduce our reliance on chemical pesticides are urgently needed to meet the UN sustainable development goals for global food security. Mycoparasitic oomycetes such as Pythium oligandrum and Pythium periplocum, have potential for the biological control of plant diseases that threaten crops and have attracted much attention due to their abilities to antagonize plant pathogens and modulate plant immunity. Studies of the molecular and genetic determinants of mycoparasitism in these species have been less well developed than those of their fungal counterparts. Carbohydrate-active enzymes (CAZymes) from P. oligandrum and P. periplocum are predicted to be important components of mycoparasitism, being involved in the degradation of the cell wall of their oomycete and fungal prey species. To explore the evolution of CAZymes of these species we performed an in silico identification and comparison of the full CAZyme complement (CAZyome) of the two mycoparasitic Pythium species (P. oligandrum and P. periplocum), with seven other Pythium species, and four Phytophthora species. Twenty CAZy gene families involved in the degradation of cellulose, hemicellulose, glucan, and chitin were expanded in, or unique to, mycoparasitic Pythium species and several of these genes were expressed during mycoparasitic interactions with either oomycete or fungal prey, as revealed by RNA sequencing and quantitative qRT-PCR. Genes from three of the cellulose and chitin degrading CAZy families (namely AA9, GH5_14, and GH19) were expanded via tandem duplication and predominantly located in gene sparse regions of the genome, suggesting these enzymes are putative pathogenicity factors able to undergo rapid evolution. In addition, five of the CAZy gene families were likely to have been obtained from other microbes by horizontal gene transfer events. The mycoparasitic species are able to utilize complex carbohydrates present in fungal cell walls, namely chitin and N-acetylglucosamine for growth, in contrast to their phytopathogenic counterparts. Nonetheless, a preference for the utilization of simple sugars for growth appears to be a common trait within the oomycete lineage.

Comparative genomics highlights the importance of drug efflux transporters during evolution of mycoparasitism in Clonostachys subgenus Bionectria (Fungi, Ascomycota, Hypocreales).

Various strains of the mycoparasitic fungal species Clonostachys rosea are used commercially as biological control agents for the control of fungal plant diseases in agricultural crop production. Further improvements of the use and efficacy of C. rosea in biocontrol require a mechanistic understanding of the factors that determines the outcome of the interaction between C. rosea and plant pathogenic fungi. Here, we determined the genome sequences of 11 Clonostachys strains, representing five species in Clonostachys subgenus Bionectria, and performed a comparative genomic analysis with the aim to identify gene families evolving under selection for gene gains or losses. Several gene families predicted to encode proteins involved in biosynthesis of secondary metabolites, including polyketide synthases, nonribosomal peptide syntethases and cytochrome P450s, evolved under selection for gene gains (p ≤ .05) in the Bionectria subgenus lineage. This was accompanied with gene copy number increases (p ≤ .05) in ATP‐binding cassette (ABC) transporters and major facilitator superfamily (MFS) transporters predicted to contribute to drug efflux. Most Clonostachys species were also characterized by high numbers of auxiliary activity (AA) family 9 lytic polysaccharide monooxygenases, AA3 glucose–methanol–choline oxidoreductases and additional carbohydrate‐active enzyme gene families with putative activity (or binding) towards xylan and rhamnose/pectin substrates. Particular features of the C. rosea genome included expansions (p ≤ .05) of the ABC‐B4 multidrug resistance transporters, the ABC‐C5 multidrug resistance‐related transporters and the 2.A.1.3 drug:H + antiporter‐2 MFS drug resistance transporters. The ABC‐G1 pleiotropic drug resistance transporter gene abcG6 in C. rosea was induced (p ≤ .009) by exposure to the antifungal Fusarium mycotoxin zearalenone (1121‐fold) and various fungicides. Deletion of abcG6 resulted in mutants with reduced (p < .001) growth rates on media containing the fungicides boscalid, fenhexamid and iprodione. Our results emphasize the role of biosynthesis of, and protection against, secondary metabolites in Clonostachys subgenus Bionectria.

The cause and potential solution to the Fusarium wilt disease in banana plants

The Fusarium wilt disease of banana caused by the soil-borne fungal pathogen Fusarium oxysporum f. sp. cubense is currently considered the most prominent disease that threatens the global fruit production. Control of this pathogen is essential to guarantee the supply of banana fruits. The use of chemical pesticides is a common practice for its control; however, this causes contamination of soils, water and atmosphere, and also affects the human health. The knowledge of natural antagonists of Fusarium oxysporum f. sp. cubense is a reliable alternative to develop crop protection strategies. Concerning this, the genus Trichoderma comprises mycoparasitic species adapted to distinct environmental and soil conditions. The features of Trichoderma have enabled its use as an effective biological control agent, but this potential must be extended in order to prevent the economic losses caused by the Fusarium wilt. In this review we present essential information about two contrasting fungal inhabitants of the soil: a group of phytopathogens that produces deleterious consequences in banana plants and its potential antagonists that will provide novel methods of biological control.

Taxonomic notes on eight species of obligate mycoparasites in the genus Syncephalis isolated from soil and dung

ABSTRACT Species of Syncephalis (Zoopagomycotina, Piptocephalidaceae) are obligate mycoparasites that grow on common saprobic species of Mortierellomycotina and Mucoromycotina in soil and dung. Despite their ubiquitous occurrence across the globe, fungi in the genus Syncephalis are understudied, and there are few modern taxonomic treatments of these fungi. In order to clarify species concepts in the genus, we provide morphological data and discuss seven classical Syncephalis species: S. basibulbosa, S. cordata, S. depressa, S. hypogena, S. intermedia, S. nodosa, and S. sphaerica. Three of these species are only known as herbarium specimens (S. basibulbosa, S. cordata, S. intermedia). We have isolated co-cultures of the remaining parasites (S. depressa, S. nodosa, and S. sphaerica) on their host fungi both from nature and from culture collections. The remaining taxon (S. hypogena) was revived from a lyophilized culture. We provide photos and updated descriptions for all of these species as well as new geographic data and references to documented herbarium specimens for each taxon. In addition, we also describe the new species S. latigena.

The presence of Phytophthora infestans in the rhizosphere of a wild Solanum species may contribute to off-season survival and pathogenicity

We evaluated oomycete presence and abundance in the rhizosphere of wild perennial Solanum species to investigate the presence of plant pathogenic or mycoparasitic species. Furthermore, we investigated whether these plant species could function as hosts, or associated plants, for off-season survival of economically important pathogens. We collected soil samples in Sweden from Solanum dulcamara and as a control from Vitis vinifera over all four seasons of a year, and in New Zealand from Solanum nigrum and Solanum laciniatum in the summer. Species identification, confirmed by ITS and Cox2 sequencing, and root infection assays on the crop plant Solanum tuberosum and on S. dulcamara, suggested the presence of mainly Pythiales species. In Sweden, we also found evidence for the presence of Phytophthora infestans, the causal agent of potato late blight, in the rhizosphere of S. dulcamara. These Ph. infestans isolates had no negative effects on root growth of S. dulcamara in Sweden, but were more pathogenic on potato leaves than a common lab strain. Oomycete diversity measures indicated a high similarity between seasons and countries. In conclusion, our study suggests a previously unknown overwintering strategy for the pathogen Ph. infestans, indicating a possible influence of the wild species S. dulcamara on the epidemiology of potato late blight in Sweden.

Osmotolerance as a determinant of microbial ecology: A study of phylogenetically diverse fungi

Osmotic stress induced by high solute concentration can prevent fungal metabolism and growth due to alterations in properties of the cytosol, changes in turgor, and the energy required to synthesize and retain compatible solutes. We used germination to quantify tolerance/sensitivity to the osmolyte KCl (0.1–4.5 M, in 0.1 M increments) for 71 strains (40 species) of ecologically diverse fungi. These include 11 saprotrophic species (17 strains, including two xerophilic species), five mycoparasitic species (five strains), six plant-pathogenic species (13 strains), and 19 entomopathogenic species (36 strains). A dendrogram obtained from cluster analyses, based on KCl inhibitory concentrations 50 % and 90 % calculated by Probit Analysis, revealed three groups of fungal isolates accordingly to their osmotolerance. The most-osmotolerant group (Group 3) contained the majority of saprotrophic fungi, and Aspergillus niger (F19) was the most tolerant. The highly xerophilic Aspergillus montevidense and Aspergillus pseudoglaucus were the second- and third-most tolerant species, respectively. All Aspergillus and Cladosporium species belonged to Group 3, followed by the entomopathogens Colletotrichum fioriniae, Simplicillium lanosoniveum, and Trichothecium roseum. Group 2 exhibited a moderate osmotolerance, and included plant-pathogens such as Colletotrichum and Fusarium, mycoparasites such as Clonostachys spp, some saprotrophs such as Mucor and Penicillium spp., and some entomopathogens such as Isaria, Lecanicillium, Mariannaea, Simplicillium, and Torrubiella. Group 1 contained the osmo-sensitive strains: the rest of the entomopathogens and the mycoparasitic Gliocladium and Trichoderma. Although stress tolerance did not correlate with their primary ecological niche, classification of these 71 fungal strains was more closely aligned with their ecology than with their phylogenetic relatedness. We discuss the implications for both microbial ecology and fungal taxonomy.

Comparative evolutionary histories of fungal proteases reveal gene gains in the mycoparasitic and nematode-parasitic fungus Clonostachys rosea

BackgroundThe ascomycete fungus Clonostachys rosea (order Hypocreales) can control several important plant diseases caused by plant pathogenic fungi and nematodes. Subtilisin-like serine proteases are considered to play an important role in pathogenesis in entomopathogenic, mycoparasitic, and nematophagous fungi used for biological control. In this study, we analysed the evolutionary histories of protease gene families, and investigated sequence divergence and regulation of serine protease genes in C. rosea.ResultsProteases of selected hypocrealean fungal species were classified into families based on the MEROPS peptidase database. The highest number of protease genes (590) was found in Fusarium solani, followed by C. rosea with 576 genes. Analysis of gene family evolution identified non-random changes in gene copy numbers in the five serine protease gene families S1A, S8A, S9X, S12 and S33. Four families, S1A, S8A, S9X, and S33, displayed gene gains in C. rosea. A gene-tree / species-tree reconciliation analysis of the S8A family revealed that the gene copy number increase in C. rosea was primarily associated with the S08.054 (proteinase K) subgroup. In addition, regulatory and predicted structural differences, including twelve sites evolving under positive selection, among eighteen C. rosea S8A serine protease paralog genes were also observed. The C. rosea S8A serine protease gene prs6 was induced during interaction with the plant pathogenic species F. graminearum.ConclusionsNon-random increases in S8A, S9X and S33 serine protease gene numbers in the mycoparasitic species C. rosea, Trichoderma atroviride and T. virens suggests an involvement in fungal-fungal interactions. Regulatory and predicted structural differences between C. rosea S8A paralogs indicate that functional diversification is driving the observed increase in gene copy numbers. The induction of prs6 expression in C. rosea during confrontation with F. graminearum suggests an involvement of the corresponding protease in fungal-fungal interactions. The results pinpoint the importance of serine proteases for ecological niche adaptation in C. rosea, including a potential role in the mycoparasitic attack on fungal prey.

Harnessing the power of phylogenomics to disentangle the directionality and signatures of interkingdom host jumping in the parasitic fungal genus Tolypocladium

ABSTRACTHost specialization is common among parasitic fungi; however, there are examples when transitions in host specificity between disparately related hosts have occurred. Here, we examine the interkingdom host jump from insect pathogenicity and mycoparasitism in Tolypocladium. Previous phylogenetic inferences made using only a few genes and with poor support reconstructed an ancestral character state of insect pathogenesis, a transition to mycoparasitism, and reversions to insect pathogenesis. To further explore the directionality and genes underlying the transitions in host, we sequenced two additional species of Tolypocladium (T. capitatum and T. paradoxum) and used phylogenomics to compare two insect pathogens and two mycoparasites. Our whole-genome-scale analysis suggests that the diversification of Tolypocladium species happened relatively quickly and that the truffle parasites form a monophyletic, derived lineage within the genus that is the result of a single ecological transition or host jump from insects to fungi. A significant amount of gene tree/species tree discordance occurs within the data set, and we infer this to be the product of both an historical hybridization event and incomplete lineage sorting that was likely because of the rapid diversification of the clade. Furthermore, comparative genomic analyses revealed a set of genes that are exclusive to the mycoparasitic species. These potentially mycoparasitic gene clusters were characterized by a reduced proportion of secreted proteins when compared with entomopathogen-enriched genes and involved the reshaping of the fungal secretome in the ecological context of mycoparasitism.

Tuberculina photiniae sp. nov. (Helicobasidiales, Basidiomycota) supported by morphological characteristics and phylogenetic data

A new mycoparasitic fungal species, Tuberculina photiniae sp. nov., is proposed based on morphological and molecular evidence. The species is characterized by its depressed hemispherical pale lilac to greyish purple sporodochia breaking through leaf surfaces, septated conidiophores with vinaceous lower parts and colourless upper parts, and the presence of colourless globose, subglobose or scarcely wide-ellipsoid conidia. Sequences of ITS and LSU nrRNA gene regions of the studied samples were generated, and phylogenetic analyses were performed with maximum likelihood, maximum parsimony and Bayesian inference methods. The phylogenetic analysis based on molecular data of ITS sequences showed that Tuberculina photiniae belongs to the Tuberculina-Helicobasidium clade and is closely related to H. longisporum and H. mompa. Further investigation was carried out for representative taxa in the Tuberculina-Helicobasidium group based on ITS+nLSU sequences in which the results demonstrated that the new species formed a monophyletic lineage and grouped with H. longisporum and H. mompa. Both morphological and molecular evidence confirmed the placement of the new species in the Tuberculina-Helicobasidium clade.

Modification of Susceptible and Toxic Herbs on Grassland Disease.

Recent research shows that continuous overgrazing not only causes grassland biodiversity to decline, but also causes light fungal disease. Achnatherum inebrians is susceptible to fungal diseases and increases in prevalence during over grazing due its toxicity to livestock. This study aimed to examine the effects of A. inebrians on biological control organisms and levels of plant diseases in overgrazed grasslands in northwestern China. The results showed that A. inebrians plants were seriously infected by fungal diseases and that this led to a high incidence of the mycoparasitic species Ampelomyces quisqualis and Sphaerellopsis filum. In addition, the fungivore, Aleocharinae, was found only in the soil growing A. inebrians rather than in the overgrazed area without A. inebrians. Overall, in an overgrazed grassland fenced for one year, disease levels in blocks without A. inebrians were significantly higher than those in blocks with A. inebrians. Our findings indicated that the disease susceptible, toxic A. inebrians can help control plant disease levels in overgrazed grasslands.

Isolation and expression of two polyketide synthase genes from Trichoderma harzianum 88 during mycoparasitism.

Metabolites of mycoparasitic fungal species such as Trichoderma harzianum 88 have important biological roles. In this study, two new ketoacyl synthase (KS) fragments were isolated from cultured Trichoderma harzianum 88 mycelia using degenerate primers and analysed using a phylogenetic tree. The gene fragments were determined to be present as single copies in Trichoderma harzianum 88 through southern blot analysis using digoxigenin-labelled KS gene fragments as probes. The complete sequence analysis in formation of pksT-1 (5669 bp) and pksT-2 (7901 bp) suggests that pksT-1 exhibited features of a non-reducing type I fungal PKS, whereas pksT-2 exhibited features of a highly reducing type I fungal PKS. Reverse transcription polymerase chain reaction indicated that the isolated genes are differentially regulated in Trichoderma harzianum 88 during challenge with three fungal plant pathogens, which suggests that they participate in the response of Trichoderma harzianum 88 to fungal plant pathogens. Furthermore, disruption of the pksT-2 encoding ketosynthase–acyltransferase domains through Agrobacterium-mediated gene transformation indicated that pksT-2 is a key factor for conidial pigmentation in Trichoderma harzianum 88.

Identification of novel gene clusters for secondary metabolism in Trichoderma genomes

Trichoderma species are widely used in agriculture as biofungicides. These fungi are rich source of secondary metabolites and the mycoparasitic species are enriched in genes for biosynthesis of secondary metabolites. Most often, genes for secondary metabolism are clustered in fungal genomes. Previously, no systematic study was undertaken to identify the secondary-metabolism related gene clusters in Trichoderma genomes. In the present study, a survey of the three Trichoderma genomes viz. T. reesei, T. atroviride and T. virens, was made to identify the putative gene clusters associated with secondary metabolism. In T. reesei genome, we identified one new NRPS and 6 new PKS clusters, which is much less than that found in T. atroviride (4 and 8) and T. virens (8 and 7). This work would pave the way for discovery of novel secondary metabolites and pathways in Trichoderma.