Three new species of Trichoderma with hyaline ascospores from China

Sclerotia degradation by Trichoderma-mycoparasitic; an effective and sustainable trend in the drop lettuce disease control caused by Sclerotinia sclerotiorum

Controlling the hazard of sclerotia produced by the Sclerotinia sclerotiorum is very complex, and it is urgent to adopt an effective method that is harmonious environmentally to control the disease. Among the six isolates isolated from the rhizosphere of lettuce, the isolate HZA84 demonstrated a high activity in its antagonism towards Sclerotinia sclerotiorum in vitro, and produces siderophore. By amplification of internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF1-α), and RNA polymerase II subunit (RPB2) genes, the isolate HZA84 was identified as Trichoderma asperellum, which was confirmed by analysis of phylogenetic tree. The Scanning electron microscope monitoring detected that the isolate HZA84 spread over the sclerotial surface, thus, damaging, decomposing, and distorting the globular cells of the outer cortex of the sclerotia. The Real-time polymerase chain reaction (RT-qPCR) analysis disclosed the overexpression of two genes (chit33 and chit37) encoding the endochitinase in addition to one gene (prb1) encoding the proteinase during 4 and 8 days of the parasitism behavior of isolate HZA84 on the sclerotia surface. These enzymes aligned together in the sclerotia destruction by hyperparasitism. On the other hand, the pots trial revealed that spraying of isolate HZA84 reduced the drop disease symptoms of lettuce. The disease severity was decreased by 19.33 and the biocontrol efficiency was increased by 80.67% within the fourth week of inoculation. These findings magnify the unique role of Trichoderma in disrupting the development of plant diseases in sustainable ways.

Three new species of Trichoderma (Hypocreales, Hypocreaceae) from soils in China

Trichoderma spp. are diverse fungi with wide distribution. In this study, we report on three new species of Trichoderma, namely T.nigricans, T.densissimum and T.paradensissimum, collected from soils in China. Their phylogenetic position of these novel species was determined by analyzing the concatenated sequences of the second largest nuclear RNA polymerase subunit encoding gene (rpb2) and the translation elongation factor 1- alpha encoding gene (tef1). The results of the phylogenetic analysis showed that each new species formed a distinct clade: T.nigricans is a new member of the Atroviride Clade, and T.densissimum and T.paradensissimum belong to the Harzianum Clade. A detailed description of the morphology and cultural characteristics of the newly discovered Trichoderma species is provided, and these characteristics were compared with those of closely related species to better understand the taxonomic relationships within the Trichoderma.

Phylogenetic Analysis of Trichoderma Species Associated with Green Mold Disease on Mushrooms and Two New Pathogens on Ganoderma sichuanense

Edible and medicinal mushrooms are extensively cultivated and commercially consumed around the world. However, green mold disease (causal agent, Trichoderma spp.) has resulted in severe crop losses on mushroom farms worldwide in recent years and has become an obstacle to the development of the Ganoderma industry in China. In this study, a new species and a new fungal pathogen on Ganoderma sichuanense fruitbodies were identified based on the morphological characteristics and phylogenetic analysis of two genes, the translation elongation factor 1-α (TEF1) and the second-largest subunit of RNA polymerase II (RPB2) genes. The new species, Trichoderma ganodermatigerum sp. nov., belongs to the Harzianum clade, and the new fungal pathogen was identified as Trichoderma koningiopsis. Furthermore, in order to better understand the interaction between Trichoderma and mushrooms, as well as the potential biocontrol value of pathogenic Trichoderma, we summarized the Trichoderma species and their mushroom hosts as best as possible, and the phylogenetic relationships within mushroom pathogenic Trichoderma species were discussed.

Five new species of Trichoderma from moist soils in China

Trichoderma isolates were collected from moist soils near a water source in different areas of China. ITS sequences were submitted to MIST (Multiloci Identification System for Trichoderma) and meets the Trichoderma [ITS76] standard. Combined analyses of phylogenetic analyses of both phylograms (tef1-α and rpb2) and morphological characteristics, revealed five new species of Trichoderma, namely Trichoderma hailarense, T. macrofasciculatum, T. nordicum, T. shangrilaense and T. vadicola. Phylogenetic analyses showed T. macrofasciculatum and T. shangrilaense belong to the Polysporum clade, T. hailarense, while T. nordicum and T. vadicola belong to the Viride clade. Each new taxon formed a distinct clade in phylogenetic analysis and have unique sequences of tef1-α and rpb2 that meet the Trichoderma new species standard. The conidiation of T. macrofasciculatum typically appeared in white pustules in concentric rings on PDA or MEA and its conidia had one or few distinctly verrucose. Conidiophores of T. shangrilaense are short and rarely branched, phialides usually curved and irregularly disposed. The aerial mycelium of T. hailarense and T. vadicola formed strands to floccose mat, conidiation tardy and scattered in tufts, conidiophores repeatedly rebranching in dendriform structure. The phialides of T. nordicum lageniform are curved on PDA and its conidia are globose to obovoidal and large.

Heterologous expression of a single fungal HR-PKS leads to the formation of diverse 2-alkenyl-tetrahydropyrans in model fungi

2-Alkenyl-tetrahydropyrans belong to a rare class of natural products that exhibit broad antifungal activities. Their structural instability and rareness in nature have restrained their discovery and drug development. In this study, the heterologous expression of a single highly reducing polyketide synthase (HR-PKS, App1) from Trichoderma applanatum in Aspergillus nidulans leads to the formation of seven 2-alkenyl-tetrahydropyran derivatives including one known compound virensol C (1) and six new compounds (2-7). However, introducing App1 into Saccharomyces cerevisiae resulted in the identification of additional two 2-alkenyl-tetrahydropyrans lacking the hydroxyl or methoxyl group at the C-2 position (8 and 9). The structures of the isolated compounds were elucidated by extensive spectroscopic analysis using NMR and HR-ESI-MS.

Bioprospecting Trichoderma: A Systematic Roadmap to Screen Genomes and Natural Products for Biocontrol Applications

Natural products derived from microbes are crucial innovations that would help in reaching sustainability development goals worldwide while achieving bioeconomic growth. Trichoderma species are well-studied model fungal organisms used for their biocontrol properties with great potential to alleviate the use of agrochemicals in agriculture. However, identifying and characterizing effective natural products in novel species or strains as biological control products remains a meticulous process with many known challenges to be navigated. Integration of recent advancements in various "omics" technologies, next generation biodesign, machine learning, and artificial intelligence approaches could greatly advance bioprospecting goals. Herein, we propose a roadmap for assessing the potential impact of already known or newly discovered Trichoderma species for biocontrol applications. By screening publicly available Trichoderma genome sequences, we first highlight the prevalence of putative biosynthetic gene clusters and antimicrobial peptides among genomes as an initial step toward predicting which organisms could increase the diversity of natural products. Next, we discuss high-throughput methods for screening organisms to discover and characterize natural products and how these findings impact both fundamental and applied research fields.

Carbon metabolic profiling of Trichoderma strains provides insight into potential ecological niches

Many Trichoderma species are cosmopolitan and widespread free-living fungi in various ecological environment, and many are economically important in the fields of agriculture and industry. However, carbon metabolism profiles of Trichoderma species have not been characterized in detail. In this study, Biolog FF MicroPlates were used to contrast carbon utilization and the differences among five Trichoderma species, each representing a unique phenotype. Their metabolic abilities varied greatly. Species producing cellulases and chitinases and with phosphate-solubilizing activities exhibited high efficiency of substrate utilization, whereas low efficiency was shown by saline-alkaline-tolerant species that metabolized simple carbon sources. Species producing cellulases at high levels may be specified to decompose and assimilate cellulose and hemicellulose in woody substrates, and those producing chitinases may have mycoparasitic roles. Species with plant growth-promoting traits are good at uptake of exudates from plant roots. Overall, metabolic models reflect nutritional adaptation of Trichoderma to diverse niches in nature.

Two New Species and a New Chinese Record of Hypocreaceae as Evidenced by Morphological and Molecular Data

To explore species diversity of Hypocreaceae, collections from Guangdong, Hubei, and Tibet of China were examined and two new species and a new Chinese record were discovered. Morphological characteristics and DNA sequence analyses of the ITS, LSU, EF-1α, and RPB2 regions support their placements in Hypocreaceae and the establishments of the new species. Hypomyces hubeiensis sp. nov. is characterized by occurrence on fruitbody of Agaricus sp., concentric rings formed on MEA medium, verticillium-like conidiophores, subulate phialides, rod-shaped to narrowly ellipsoidal conidia, and absence of chlamydospores. Trichoderma subiculoides sp. nov. is distinguished by effuse to confluent rudimentary stromata lacking of a well-developed flank and not changing color in KOH, subcylindrical asci containing eight ascospores that disarticulate into 16 dimorphic part-ascospores, verticillium-like conidiophores, subcylindrical phialides, and subellipsoidal to rod-shaped conidia. Morphological distinctions between the new species and their close relatives are discussed. Hypomyces orthosporus is found for the first time from China.

Trichodermatides E and F from fungus Trichoderma applanatum

Two new polyketide derivatives, trichodermatides E (1) and F (2), are unprecedented examples of a polyketide with 6/6/6/6 tetracyclic skeleton, together with five known analogs koninginin B (3), koninginin D (4), 7-O-methylkoninginin D (5), koninginins E and F (6-7), were isolated from the plant endophytic fungus Trichoderma applanatum. The structures of these two compounds were determined by NMR data and HR-ESI-MS analysis. The putative biosynthesis of compounds 1-7 was presented.

Discovery from a large-scaled survey of Trichoderma in soil of China

The first large-scaled survey of soil-inhabiting Trichoderma is conducted in 23 provinces of China. Twenty-three new species belonging to the green-ascospored clades are discovered. Their phylogenetic positions are determined by sequence analyses of the combined partial sequences of translation elongation factor 1-alpha and the second largest RNA polymerase subunit encoding genes. Morphology and culture characteristics are observed, described and illustrated in detail. Distinctions between the new species and their close relatives are compared and discussed. They are named as: T. aggregatum, T. alpinum, T. bannaense, T. breve, T. brevicrassum, T. byssinum, T. chlamydosporicum, T. concentricum, T. ganodermatis, T. hainanense, T. hengshanicum, T. hirsutum, T. hunanense, T. ingratum, T. liberatum, T. linzhiense, T. longisporum, T. polypori, T. pseudodensum, T. simplex, T. solum, T. undatipile and T. zayuense.

A new species of Trichoderma hypoxylon harbours abundant secondary metabolites

Some species of Trichoderma are fungicolous on fungi and have been extensively studied and commercialized as biocontrol agents. Multigene analyses coupled with morphology, resulted in the discovery of T. hypoxylon sp. nov., which was isolated from surface of the stroma of Hypoxylon anthochroum. The new taxon produces Trichoderma- to Verticillium-like conidiophores and hyaline conidia. Phylogenetic analyses based on combined ITS, TEF1-α and RPB2 sequence data indicated that T. hypoxylon is a well-distinguished species with strong bootstrap support in the polysporum group. Chemical assessment of this species reveals a richness of secondary metabolites with trichothecenes and epipolythiodiketopiperazines as the major compounds. The fungicolous life style of T. hypoxylon and the production of abundant metabolites are indicative of the important ecological roles of this species in nature.

Trichoderma Biodiversity of Agricultural Fields in East China Reveals a Gradient Distribution of Species

We surveyed the Trichoderma (Hypocreales, Ascomycota) biodiversity in agricultural fields in four major agricultural provinces of East China. Trichoderma strains were identified based on molecular approaches and morphological characteristics. In three sampled seasons (spring, summer and autumn), 2078 strains were isolated and identified to 17 known species: T. harzianum (429 isolates), T. asperellum (425), T. hamatum (397), T. virens (340), T. koningiopsis (248), T. brevicompactum (73), T. atroviride (73), T. fertile (26), T. longibrachiatum (22), T. pleuroticola (16), T. erinaceum (16), T. oblongisporum (2), T. polysporum (2), T. spirale (2), T. capillare (2), T. velutinum (2), and T. saturnisporum (1). T. harzianum, T. asperellum, T. hamatum, and T. virens were identified as the dominant species with dominance (Y) values of 0.057, 0.052, 0.048, and 0.039, respectively. The species amount, isolate numbers and the dominant species of Trichoderma varied between provinces. Zhejiang Province has shown the highest diversity, which was reflected in the highest species amount (14) and the highest Shannon–Wiener diversity index of Trichoderma haplotypes (1.46). We observed that relative frequencies of T. hamatum and T. koningiopsis under rice soil were higher than those under wheat and maize soil, indicating the preference of Trichoderma to different crops. Remarkable seasonal variation was shown, with summer exhibiting the highest biodiversity of the studied seasons. These results show that Trichoderma biodiversity in agricultural fields varies by region, crop, and season. Zhejiang Province (the southernmost province in the investigated area) had more T. hamatum than Shandong Province (the northernmost province), not only in isolate amounts but also in haplotype amounts. Furthermore, at haplotype level, only T. hamatum showed a gradient distribution from south to north in correspondence analysis among the four dominant species. The above results would contribute to the application of Trichoderma biocontrol strains.

Two new hyaline-ascospored species of Trichoderma and their phylogenetic positions

Collections of hypocrealean fungi found on decaying wood in subtropical regions of China were examined. Two new species, Trichoderma confluens and T. hubeiense, were discovered and are described. Trichoderma confluens is characterized by its widely effuse to rarely pulvinate, yellow stromata with densely disposed yellowish brown ostioles, simple acremonium- to verticillium-like conidiophores, hyaline conidia and multiform chlamydospores. Trichoderma hubeiense has pulvinate, grayish yellow stromata with brownish ostioles, trichoderma- to verticillium-like conidiophores and hyaline conidia. The phylogenetic positions of the two fungi were investigated based on sequence analyses of RNA polymerase II subunit b and translation elongation factor 1-α genes. The results indicate that T. confluens belongs to the Hypocreanum clade and is associated with but clearly separated from T. applanatum and T. decipiens. Trichoderma hubeiense belongs to the Polysporum clade and related to T. bavaricum but obviously differs from other members of the clade in sequence data. Morphological distinctions between the new species and their close relatives are noted and discussed.