Search Results (6)

Commercial production of the button mushroom, Agaricus bisporus (Lange) Imbach, is threatened by various pests and mycopathogenic microorganisms. Sciarid flies (Sciaridae) of the genus Lycoriella are considered as major pests, while major pathogens include the fungi Lecanicillium fungicola (Preuss), Zare and Gams, Hypomyces perniciosus Magnus, Cladobotryum spp., and Trichoderma aggressivum Samuels & W. Gams, the causative agents of dry bubble, wet bubble, cobweb, and green mold diseases, respectively. Control of mushroom pests and diseases has long relied on synthetic chemical pesticides. Pesticide resistance and various health and environmental issues have created a need for sustainable and eco-friendly alternatives to the use of synthetic chemical pesticides for mushroom pest and disease control. The concept of bioprotection, which involves using biological control agents (BCAs) and biopesticide products, offers a viable alternative. The entomopathogenic nematode Steinernema feltiae (Filipjev) and predatory mite Stratiolaelaps scimitus (Womersley) are the most important invertebrate BCAs, while the bacteria Bacillus thuringiensis Berliner, B. amyloliquefaciens, and B. velezensis stand out as the most widely used microbial BCAs/biopesticides. Azadirachtin- and pyrethrum-based products are the most important biochemical biopesticides. Bioprotection agents require inclusion in the integrated pest and disease management (IPDM) programs in order to achieve their full effectiveness. Full article

The white collar proteins WC1 and WC2 interact with each other to form a white collar complex acting as a well-known transcription regulator required for the operation of the circadian clock in Neurospora, but their roles in insect-pathogenic fungal lifecycles remain poorly understood. Here, we report that WC1 and WC2 orthologs co-regulate the conidiation capacity and conidial resistance to solar ultraviolet-B (UVB) irradiation in Beauveria bassiana, after their high activities in the photorepair of UVB-induced DNA damages were elucidated previously in the insect mycopathogen, which features non-rhythmic conidiation and high conidiation capacity. The conidial yield, UVB resistance, and photoreactivation rate of UVB-impaired conidia were greatly reduced in the null mutants of wc1 and wc2 compared to their control strains. However, many other lifecycle-related phenotypes, except the antioxidant response, were rarely affected in the two mutants. Transcriptomic analysis revealed largely overlapping roles for WC1 and WC2 in regulating the fungal gene networks. Most of the differentially expressed genes identified from the null mutants of wc1 (1380) and wc2 (1001) were co-downregulated (536) or co-upregulated (256) at similar levels, including several co-downregulated genes required for aerial conidiation and DNA photorepair. These findings expand a molecular basis underlying the fungal adaptation to solar UV irradiation and offer a novel insight into the genome-wide co-regulatory roles of WC1 and WC2 in B. bassiana’s asexual development and in vivo photoreactivation against solar UV damage. Full article

The Rad4-Rad23-Rad33 complex plays an essential anti-ultraviolet (UV) role depending on nucleotide excision repair (NER) in budding yeast but has been rarely studied in filamentous fungi, which possess two Rad4 paralogs (Rad4A/B) and orthologous Rad23 and rely on the photorepair of UV-induced DNA lesions, a distinct mechanism behind the photoreactivation of UV-impaired cells. Previously, nucleocytoplasmic shuttling Rad23 proved to be highly efficient in the photoreactivation of conidia inactivated by UVB, a major component of solar UV, due to its interaction with Phr2 in Beauveria bassiana, a wide-spectrum insect mycopathogen lacking Rad33. Here, either Rad4A or Rad4B was proven to localize exclusively in the nucleus and interact with Rad23, which was previously shown to interact with the white collar protein WC2 as a regulator of two photorepair-required photolyases (Phr1 and Phr2) in B. bassiana. The Δrad4A mutant lost ~80% of conidial UVB resistance and ~50% of activity in the photoreactivation of UVB-inactivated conidia by 5 h light exposure. Intriguingly, the reactivation rates of UVB-impaired conidia were observable only in the presence of rad4A after dark incubation exceeding 24 h, implicating extant, but infeasible, NER activity for Rad4A in the field where night (dark) time is too short. Aside from its strong anti-UVB role, Rad4A played no other role in B. bassiana’s lifecycle while Rad4B proved to be functionally redundant. Our findings uncover that the anti-UVB role of Rad4A depends on the photoreactivation activity ascribed to its interaction with Rad23 linked to WC2 and Phr2 and expands a molecular basis underlying filamentous fungal adaptation to solar UV irradiation on the Earth’s surface. Full article

Fungi in the Entomophthorales order can cause insect disease and epizootics in nature, contributing to biological pest control in agriculture and forestry. Most Entomophthorales have narrow host ranges, limited to the arthropod family level; however, rare genomic information about host-specific fungi has been reported. Conidiation is crucial for entomopathogenic fungi to explore insect resources owing to the important roles of conidia in the infection cycle, such as dispersal, adhesion, germination, and penetration into the host hemocoel. In this study, we analyzed the whole genome sequence of the aphid-obligate pathogen Conidiobolus obscurus strain ARSEF 7217 (Entomophthoromycotina), using Nanopore technology from Biomarker Technologies (Beijing, China). The genome size was 37.6 Mb, and encoded 10,262 predicted genes, wherein 21.3% genes were putatively associated to the pathogen–host interaction. In particular, the serine protease repertoire in C. obscurus exhibited expansions in the trypsin and subtilisin classes, which play vital roles in the fungus’ pathogenicity. Differentially expressed transcriptomic patterns were analyzed in three conidiation stages (pre-conidiation, emerging conidiation, and post-conidiation), and 2915 differentially expressed genes were found to be associated with the conidiation process. Furthermore, a weighted gene co-expression network analysis showed that 772 hub genes in conidiation are mainly involved in insect cuticular component degradation, cell wall/membrane biosynthesis, MAPK signaling pathway, and transcription regulation. Our findings of the genomic and transcriptomic features of C. obscurus help reveal the molecular mechanism of the Entomophthorales pathogenicity, which will contribute to improving fungal applications in pest control. Full article

Mbp1 protein acts as a DNA-binding protein in MluI cell cycle box-binding complex (MBF) and plays an essential role in filamentous myco-pathogen Beauveria bassiana.In the current study, BbSwi6 (a homologue of yeast Swi6) was functionally characterized in B.bassiana. Both BbSwi6 and BbMbp1 localize in the nucleus and display a direct interaction relationship which is indicated by a yeast two-hybrid assay. BbSwi6 significantly contributes to hyphal growth, asexual sporulation and virulence. On the aerial surface, ΔBbSwi6 grew slower on various nutrients and displayed abnormal conidia-producing structures, which hardly produced conidia. In liquid media, BbSwi6 loss led to 90% reduction in blastospore yield. Finally, the virulence of the ΔBbSwi6 mutant was modestly weakened with a reduction of 20% in median lethal time. Comparative transcriptomics revealed that BbSwi6 mediated different transcriptomes during fungal development into conidia and blastospores. Notably, under the indicated condition, the BbSwi6-mediated transcriptome significantly differed to that mediated by BbMbp1. Our results demonstrate that, in addition to their roles as the interactive components in MBF, BbSwi6 and BbMbp1 mediate divergent genetic pathways during morphological transitions in B. bassiana. Full article

Mycopathogens of economically important exotic invasive insects in forests of northeastern USA have been the subject of research at the Entomology Research Laboratory, University of Vermont, for the last 20 years. Elongate hemlock scale, European fruit lecanium, hemlock woolly adelgid and pear thrips were analyzed for the presence of mycopathogens, in order to consider the potential for managing these pests with biological control. Fungal cultures isolated from insects with signs of fungal infection were identified based on morphological characters and DNA profiling. Mycopathogens recovered from infected insects were subdivided into three groups, i.e., specialized entomopathogenic; facultative entomopathogens; ubiquitous opportunistic contaminants. Epizootics were caused by fungi in the specialized group with the exception of M. microspora, P. marquandii and I. farinosa. Inoculation of insects in laboratory and field conditions with B. bassiana, L. muscarium and Myriangium sp. caused insect mortality of 45 to 95%. Although pest populations in the field seemed severely compromised after treatment, the remnant populations re-established themselves after the winter. Although capable of inducing high mortality, a single localized aerial application of a soil-dwelling fungus does not maintain long-time suppression of pests. However, it can halt their range expansion and maintain populations below the economic threshold level without the use of expensive insecticides which have a negative impact on the environment. Full article