Publications

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identification of a hybrid pks-nrps required for the biosynthesis of ng-391 in metarhizium robertsii.the fungal entomopathogen metarhizium robertsii (formerly known as m. anisopliae var. anisopliae) is a prolific producer of secondary metabolites of which very little is known at the genetic level. to establish the genetic bases for the biosynthesis of the mutagenic compound ng- 391, we identified a 19,818 kb genomic region harboring the predicted hybrid polyketide synthase-nonribosomal peptide synthetase ngs1, plus five additional orfs. ngs1 knockouts generated by agrobacterium-mediated transfo ...201020355253
mrt, a gene unique to fungi, encodes an oligosaccharide transporter and facilitates rhizosphere competency in metarhizium robertsii.the symbiotic associations between rhizospheric fungi and plants have enormous environmental impact. fungi are crucial to plant health as antagonists of pathogens and herbivores and facilitate the uptake of soil nutrients. however, little is known about the plant products obtained by fungi in exchange or how they are transported through the symbiotic interface. here, we demonstrate that sucrose and raffinose family oligosaccharides in root exudates are important for rhizosphere competence in the ...201020837701
quantification of cyclobutane pyrimidine dimers induced by uvb radiation in conidia of the fungi aspergillus fumigatus, aspergillus nidulans, metarhizium acridum and metarhizium robertsii.conidia are responsible for reproduction, dispersal, environmental persistence and host infection of many fungal species. one of the main environmental factors that can kill and/or damage conidia is solar uv radiation. cyclobutane pyrimidine dimers (cpd) are the major dna photoproducts induced by uvb. we examined the conidial germination kinetics and the occurrence of cpd in dna of conidia exposed to different doses of uvb radiation. conidia of aspergillus fumigatus, aspergillus nidulans and met ...201020860693
diversity of rhizosphere associated entomopathogenic fungi of perennial herbs, shrubs and coniferous trees.understanding habitat selection of fungal entomopathogens is critical to improve the efficacy, persistence and cost of these fungi as microbial insecticides. this study sought to determine the prevalence of metarhizium and beauveria spp. isolated from the rhizosphere of strawberry, blueberry, grape and christmas tree crops in the willamette valley of oregon. entomopathogenic fungi were assigned to thirteen species based on molecular phylogenetic criteria. four species of metarhizium were isolate ...201021056569
visible light during mycelial growth and conidiation of metarhizium robertsii produces conidia with increased stress tolerance.light conditions during mycelial growth are known to influence fungi in many ways. the effect of visible-light exposure during mycelial growth was investigated on conidial tolerance to uvb irradiation and wet heat of metarhizium robertsii, an insect-pathogenic fungus. two nutrient media and two light regimens were compared. conidia were produced on (a) potato dextrose agar plus yeast extract medium (pday) (a1) under dark conditions or (a2) under continuous visible light (provided by two fluoresc ...201121204917
three sympatrically occurring species of metarhizium show plant rhizosphere specificity.here we tested the hypothesis that species of the soil-inhabiting insect pathogenic fungus metarhizium are not randomly distributed in soils but show plant rhizosphere-specific associations. we isolated metarhizium from plant roots at two sites in ontario, canada, sequenced the 5' ef-1a gene to discern metarhizium species, and developed an rflp for rapid species identification. results indicated a non-random association of three metarhizium species (metarhizium robertsii, m. brunneum and m. guiz ...201121778205
a pcr-based tool for cultivation-independent detection and quantification of metarhizium clade 1.the entomopathogenic fungus metarhizium anisopliae and sister species are some of the most widely used biological control agents for insects. availability of specific monitoring and quantification tools are essential for the investigation of environmental factors influencing their environmental distribution. naturally occurring as well as released metarhizium strains in the environment traditionally are monitored with cultivation-dependent techniques. however, specific detection and quantificati ...201121821039
mrt, a gene unique to fungi, encodes an oligosaccharide transporter and facilitates rhizosphere competency in metarhizium robertsii. 201121698841
The inhibitory effect of the fungal toxin, destruxin A, on behavioural fever in the desert locust.During an infection locusts behaviourally fever by seeking out higher environmental temperatures. This behaviour places the pathogen at sub-optimal growth temperatures while improving the efficiency of the immune system, thereby prolonging the lifespan of the host. It is therefore in the interest of the pathogen to either adapt to fever-like temperatures or to evolve mechanisms to interfere with, or inhibit fever. We investigated the behavioural fever response of desert locusts to two fungal pat ...201121729702
a group iii histidine kinase (mhk1) upstream of high-osmolarity glycerol pathway regulates sporulation, multi-stress tolerance and virulence of metarhizium robertsii, a fungal entomopathogen.the role of metarhizium robertsii group iii histidine kinase (mhk1) in regulating various phenotypes of the fungal entomopathogen and the transcripts of 25 downstream genes likely associated with the phenotypes were probed by constructing δmhk1 and δmhk1/mhk1 mutants. all examined δmhk1 phenotypes except unchanged sensitivity to fungicide (dimethachlon) differed significantly from those of wild type and δmhk1/mhk1, which were similar to each other. significant phenotypic changes in δmhk1 include ...201122118192
Cold activity and tolerance of the entomopathogenic fungus Tolypocladium spp. to UV-B irradiation and heat.Studies on the stress resistance of insect-pathogenic fungi are very important to better understand the survival of these organisms in the environment. In this study, we examined the cold activity (8 ± 1°C for 7 days), UV-B tolerance (Quaite-weighted UV-B irradiance at 847.90 mW m(-2) for 1, 2, 3, and 4 h), and wet-heat tolerance (45°C for 1, 2, 3, and 4 h) of two isolates of Tolypocladiumcylindrosporum (ARSEF 3392 and 5558), one isolate of Tolypocladium geodes (ARSEF 3275), and two isolates of ...201121925183
Local adaptation of an introduced transgenic insect fungal pathogen due to new beneficial mutations.Genetically modified Metarhizium spp represent a major new arsenal for combating insect pests and insect-borne diseases. However, for these tools to be used safely and effectively, we need a much better understanding of their evolutionary potential and invasion ecology. In order to model natural as well as anthropogenic dispersal scenarios, we investigated evolutionary processes in a green fluorescent protein tagged strain of Metarhizium robertsii following transfer from a semitropical to a temp ...201122143757
Differential expression of insect and plant specific adhesin genes, Mad1 and Mad2, in Metarhizium robertsii.Metarhizium robertsii is an entomopathogenic fungus that is also plant rhizosphere competent. Two adhesin-encoding genes, Metarhizium adhesin-like protein 1 (Mad1) and Mad2, are involved in insect pathogenesis or plant root colonization, respectively. Here we examined the differential expression of the Mad genes when grown on a variety of soluble (carbohydrates and plant root exudate) and insoluble substrates (locust, tobacco hornworm, and cockroach cuticle, chitin, tomato stems, cellulose, and ...201122036295
The insect-pathogenic fungus Metarhizium robertsii (Clavicipitaceae) is also an endophyte that stimulates plant root development.• Premise of the study: The soil-inhabiting insect-pathogenic fungus Metarhizium robertsii also colonizes plant roots endophytically, thus showing potential as a plant symbiont. Metarhizium robertsii is not randomly distributed in soils but preferentially associates with the plant rhizosphere when applied in agricultural settings. Root surface and endophytic colonization of switchgrass (Panicum virgatum) and haricot beans (Phaseolus vulgaris) by M. robertsii were examined after inoculation with ...201122174335
chlorimuron ethyl as a new selectable marker for disrupting genes in the insect-pathogenic fungus metarhizium robertsii.a lack of selectable markers was a hindrance in investigating gene function in metarhizium robertsii. a reliable agrobacterium-mediated transformation system based on the use of chlorimuron ethyl as the selectable marker was developed which could serve as a useful tool to inactivate genes involved in insect pathogenicity.201121851837
the mrcyp52 cytochrome p450 monoxygenase gene of metarhizium robertsii is important for utilizing insect epicuticular hydrocarbons.fungal pathogens of plants and insects infect their hosts by direct penetration of the cuticle. plant and insect cuticles are covered by a hydrocarbon-rich waxy outer layer that represents the first barrier against infection. however, the fungal genes that underlie insect waxy layer degradation have received little attention. here we characterize the single cytochrome p450 monoxygenase family 52 (mrcyp52) gene of the insect pathogen metarhizium robertsii, and demonstrate that it encodes an enzym ...201122194968
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