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26 pages, 1695 KiB

Open AccessArticle

Transcriptomic Analysis Reveals Molecular Mechanisms Underpinning Mycovirus-Mediated Hypervirulence in Beauveria bassiana Infecting Tenebrio molitor

by Charalampos Filippou, Robert H. A. Coutts, Ioly Kotta-Loizou, Sam El-Kamand and Alexie Papanicolaou

J. Fungi 2025, 11(1), 63; https://doi.org/10.3390/jof11010063 - 15 Jan 2025

Cited by 1 | Viewed by 1208

Abstract

Mycoviral infection can either be asymptomatic or have marked effects on fungal hosts, influencing them either positively or negatively. To fully understand the effects of mycovirus infection on the fungal host, transcriptomic profiling of four Beauveria bassiana isolates, including EABb 92/11-Dm that harbors mycoviruses, was performed 48 h following infection of Tenebrio molitor via topical application or injection. Genes that participate in carbohydrate assimilation and transportation, and those essential for fungal survival and oxidative stress tolerance, calcium uptake, and iron uptake, were found to be overexpressed in the virus-infected isolate during the mid-infection stage. Mycotoxin genes encoding bassianolide and oosporein were switched off in all isolates. However, beauvericin, a mycotoxin capable of inducing oxidative stress at the molecular level, was expressed in all four isolates, indicating an important contribution to virulence against T. molitor. These observations suggest that detoxification of immune-related (oxidative) defenses and nutrient scouting, as mediated by these genes, occurs in mid-infection during the internal growth phase. Consequently, we observe a symbiotic relationship between mycovirus and fungus that does not afflict the host; on the contrary, it enhances the expression of key genes leading to a mycovirus-mediated hypervirulence effect. Full article

(This article belongs to the Section Fungal Genomics, Genetics and Molecular Biology)

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16 pages, 5994 KiB

Open AccessArticle

Characterisation of the Pathogenicity of Beauveria sp. and Metarhizium sp. Fungi Against the Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

by Nonthakorn (Beatrice) Apirajkamol, Bishwo Mainali, Phillip Warren Taylor, Thomas Kieran Walsh and Wee Tek Tay

Agriculture 2025, 15(2), 170; https://doi.org/10.3390/agriculture15020170 - 14 Jan 2025

Cited by 1 | Viewed by 2296

Abstract

Previously, we assessed the pathogenicity of eleven endemic entomopathogenic fungi (EPF), including six Beauveria isolates, four Metarhizium isolates, and one M. pingshaense, against the agricultural pest Spodoptera frugiperda (fall armyworm, FAW). We found that four Beauveria and one Metarhizium isolates were effective, with Beauveria isolates B-0571 and B-1311 exhibiting high mortality within 24 h post-spore application. This study aimed to identify and characterise the entomopathogenesis mechanisms of these isolates as potential FAW biocontrol agents. All Beauveria isolates were determined as B. bassiana, the Metarhizium isolates as two M. robertsii, one M. majus, and an unknown Metarhizium species. Despite the high mortality from B-0571 and B-1311 isolates, scanning electron microscopy showed no fungal spore germination on dead larvae 24 h after spore application. Four insecticide compound gene clusters, i.e., bassianolide, beauvericin, beauveriolide, and oosporein, were identified and characterised in all B. bassiana isolates. These compounds are hypothesised to contribute to the high early mortality rates in FAWs. Identifying and characterising gene clusters encoding these insecticide compounds in B-0571 and B-1311 will contribute to a better understanding of the entomopathogenicity of these isolates that will be vital to developing these EPF isolates as sustainable alternative FAW biocontrol agents. Full article

(This article belongs to the Section Crop Protection, Diseases, Pests and Weeds)

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19 pages, 8714 KiB

Open AccessArticle

Metabolomic Analysis Demonstrates the Impacts of Polyketide Synthases PKS14 and PKS15 on the Production of Beauvericins, Bassianolide, Enniatin A, and Ferricrocin in Entomopathogen Beauveria bassiana

by Wachiraporn Toopaang, Kullyanee Panyawicha, Chettida Srisuksam, Wei-Chen Hsu, Ching-Chih Lin, Morakot Tanticharoen, Yu-Liang Yang and Alongkorn Amnuaykanjanasin

Metabolites 2023, 13(3), 425; https://doi.org/10.3390/metabo13030425 - 14 Mar 2023

Cited by 8 | Viewed by 3076

Abstract

Beauveria bassiana is a globally distributed entomopathogenic fungus that produces various secondary metabolites to support its pathogenesis in insects. Two polyketide synthase genes, pks14 and pks15, are highly conserved in entomopathogenic fungi and are important for insect virulence. However, understanding of their mechanisms in insect pathogenicity is still limited. Here, we overexpressed these two genes in B. bassiana and compared the metabolite profiles of pks14 and pks15 overexpression strains to those of their respective knockout strains in culture and in vivo using tandem liquid chromatography-mass spectrometry (LC-MS/MS) with Global Natural Products Social Molecular Networking (GNPS). The pks14 and pks15 clusters exhibited crosstalk with biosynthetic clusters encoding insect-virulent metabolites, including beauvericins, bassianolide, enniatin A, and the intracellular siderophore ferricrocin under certain conditions. These secondary metabolites were upregulated in the pks14-overexpressing strain in culture and the pks15-overexpressing strain in vivo. These data suggest that pks14 and pks15, their proteins or their cluster components might be directly or indirectly associated with key pathways in insect pathogenesis of B. bassiana, particularly those related to secondary metabolism. Information about interactions between the polyketide clusters and other biosynthetic clusters improves scientific understanding about crosstalk among biosynthetic pathways and mechanisms of pathogenesis. Full article

(This article belongs to the Special Issue Application of Mass Spectrometry Analysis in Metabolomics)

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11 pages, 844 KiB

Open AccessArticle

Sarocladium and Lecanicillium Associated with Maize Seeds and Their Potential to Form Selected Secondary Metabolites

by Lidia Błaszczyk, Agnieszka Waśkiewicz, Karolina Gromadzka, Katarzyna Mikołajczak and Jerzy Chełkowski

Biomolecules 2021, 11(1), 98; https://doi.org/10.3390/biom11010098 - 13 Jan 2021

Cited by 21 | Viewed by 3640

Abstract

The occurrence and diversity of Lecanicillium and Sarocladium in maize seeds and their role in this cereal are poorly understood. Therefore, the present study aimed to investigate Sarocladium and Lecanicillium communities found in endosphere of maize seeds collected from fields in Poland and their potential to form selected bioactive substances. The sequencing of the internally transcribed spacer regions 1 (ITS 1) and 2 (ITS2) and the large-subunit (LSU, 28S) of the rRNA gene cluster resulted in the identification of 17 Sarocladium zeae strains, three Sarocladium strictum and five Lecanicillium lecanii isolates. The assay on solid substrate showed that S. zeae and S. strictum can synthesize bassianolide, vertilecanin A, vertilecanin A methyl ester, 2-decenedioic acid and 10-hydroxy-8-decenoic acid. This is also the first study revealing the ability of these two species to produce beauvericin and enniatin B1, respectively. Moreover, for the first time in the present investigation, pyrrocidine A and/or B have been annotated as metabolites of S. strictum and L. lecanii. The production of toxic, insecticidal and antibacterial compounds in cultures of S. strictum, S. zeae and L. lecanii suggests the requirement to revise the approach to study the biological role of fungi inhabiting maize seeds. Full article

(This article belongs to the Special Issue Fungal Metabolism - Enzymes and Bioactive Compounds)

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13 pages, 2005 KiB

Open AccessArticle

Isolation of Beauveria bassiana from the Chagas Disease Vector Triatoma infestans in the Gran Chaco Region of Argentina: Assessment of Gene Expression during Host–Pathogen Interaction

by Linda Vanesa Baldiviezo, Nicolás Pedrini, Marianela Santana, María Constanza Mannino, Lucía Beatriz Nieva, Alberto Gentile and Rubén Marino Cardozo

J. Fungi 2020, 6(4), 219; https://doi.org/10.3390/jof6040219 - 12 Oct 2020

Cited by 19 | Viewed by 3357

Abstract

A native strain of the entomopathogenic fungus Beauveria bassiana (Bb-C001) was isolated from a naturally infected Triatoma infestans, Klug (Hemiptera: Reduviidae) adult cadaver in the Gran Chaco region, Salta province, Argentina. The isolate was both phenotypic and molecularly characterized in a context of fungus-insect interaction, by measuring the expression pattern of toxin genes during infection and immune response of T. infestans. The commercial strain GHA of B. bassiana, which was previously used in field interventions to control these vectors, was used as reference in this study. The phylogenetic trees based on both ribosomal internal transcribed spacer (ITS) and elongation factor 1-alpha (EF1-α) indicated that Bb-C001 fits into a B. bassiana cluster, and the sequence-characterized amplified regions (SCAR) showed that Bb-C001 is different from the GHA strain. There were no differences between both strains regarding viability, radial growth, and conidia production, either in the median survival time or insect mortality. However, Bb-C001 showed a higher expression than GHA of the bassianolide synthetase gene (BbbslS) during infection, and similar levels of the beauvericin synthetase gene (BbbeaS). Immune-related genes of T. infestans nymphs (limpet-2 and defensin-1, -2, and -6) were later expressed and thus insects failed to stop the infection process. These results showed that B. bassiana Bb-C001 is a promised fungal strain to be incorporated in the current biological control programs of T. infestans in Salta province, Argentina. Full article

(This article belongs to the Special Issue Host-Pathogen Interactions: Insects vs Fungi)

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16 pages, 2952 KiB

Open AccessArticle

Cyclic Octamer Peptoids: Simplified Isosters of Bioactive Fungal Cyclodepsipeptides

by Assunta D’Amato, Giorgio Della Sala, Irene Izzo, Chiara Costabile, Yuichi Masuda and Francesco De Riccardis

Molecules 2018, 23(7), 1779; https://doi.org/10.3390/molecules23071779 - 19 Jul 2018

Cited by 8 | Viewed by 4356

Abstract

Cyclic peptoids have recently emerged as an important class of bioactive scaffolds with unique conformational properties and excellent metabolic stabilities. In this paper, we describe the design and synthesis of novel cyclic octamer peptoids as simplified isosters of mycotoxin depsipeptides bassianolide, verticilide A1, PF1022A and PF1022B. We also examine their complexing abilities in the presence of sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB) salt and explore their general insecticidal activity. Finally, we discuss the possible relationship between structural features of free and Na⁺-complexed cyclic octamer peptoids and bioactivities in light of conformational isomerism, a crucial factor affecting cyclic peptoids’ biomimetic potentials. Full article

(This article belongs to the Special Issue Cyclic Peptides)

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