Riboflavin induces
            <i>Metarhizium</i>
            spp. to produce conidia with elevated tolerance to
            <scp>UV</scp>
            ‐B, and upregulates photolyases, laccases and polyketide synthases genes

Pereira-Junior, Ronaldo A.; Huarte‐Bonnet, Carla; Paixão, Flávia Regina Santos da; Roberts, Donald W.; Luz, Christian; Pedrini, Nicolás; Fernandes, Éverton K. K.

doi:10.1111/jam.13743

Cited by 16 publications

(29 citation statements)

References 82 publications

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“…ns = not significant. commonly used in biological control (Braga et al, 2001(Braga et al, , 2015Paixão et al, 2017;Pereira-Junior et al, 2018;Bernardo et al, 2020). Conidia from Metarhizium species exposed to UV-B radiation (irradiances between 920 and 1,200 mW m −2 ) had both germination and survival affected in a dose-and time-dependent manner (Braga et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Tolerance to Abiotic Factors of Microsclerotia and Mycelial Pellets From Metarhizium robertsii, and Molecular and Ultrastructural Changes During Microsclerotial Differentiation

Paixão

Huarte‐Bonnet

Ribeiro-Silva

et al. 2021

Front. Fungal Biol.

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Metarhizium species fungi are able to produce resistant structures termed microsclerotia, formed by compact and melanized threads of hyphae. These propagules are tolerant to desiccation and produce infective conidia; thus, they are promising candidates to use in biological control programs. In this study, we investigated the tolerance to both ultraviolet B (UV-B) radiation and heat of microsclerotia of Metarhizium robertsii strain ARSEF 2575. We also adapted the liquid medium and culture conditions to obtain mycelial pellets from the same isolate in order to compare these characteristics between both types of propagules. We followed the peroxisome biogenesis and studied the oxidative stress during differentiation from conidia to microsclerotia by transmission electron microscopy after staining with a peroxidase activity marker and by the expression pattern of genes potentially involved in these processes. We found that despite their twice smaller size, microsclerotia exhibited higher dry biomass, yield, and conidial productivity than mycelial pellets, both with and without UV-B and heat stresses. From the 16 genes measured, we found an induction after 96-h differentiation in the oxidative stress marker genes MrcatA, MrcatP, and Mrgpx; the peroxisome biogenesis factors Mrpex5 and Mrpex14/17; and the photoprotection genes Mrlac1 and Mrlac2; and Mrlac3. We concluded that an oxidative stress scenario is induced during microsclerotia differentiation in M. robertsii and confirmed that because of its tolerance to desiccation, heat, and UV-B, this fungal structure could be an excellent candidate for use in biological control of pests under tropical and subtropical climates where heat and UV radiation are detrimental to entomopathogenic fungi survival and persistence.

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Section: Discussionmentioning

confidence: 99%

Tolerance to Abiotic Factors of Microsclerotia and Mycelial Pellets From Metarhizium robertsii, and Molecular and Ultrastructural Changes During Microsclerotial Differentiation

Paixão

Huarte‐Bonnet

Ribeiro-Silva

et al. 2021

Front. Fungal Biol.

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“…Riboflavin and sodium nitrate are already used for media supplementation of entomopathogenic fungi (Iwanicki et al 2020 ), but there are no reports of these components alone and their influence on the thermotolerance of the fungus. Pereira-Junior et al ( 2018 ) demonstrated that supplementation of BDA medium with riboflavin increased expression of photolyase, laccase, and polyketide synthase genes in M. robertsii ARSEF 2575. Thus, just as the presence of riboflavin in BDA induced the expression of components that increase tolerance to UV radiation, the presence of riboflavin in rice may induced fungal proteins production.…”

Section: Discussionmentioning

confidence: 99%

“…Riboflavin, in turn, acts as a cofactor of FMN and FAD molecules, molecules that are essential for redox homeostasis, protein folding, DNA repair, β-oxidation of fatty acids, and amino acid oxidation (Liu et al 2020 ). Thus, the presence of riboflavin in the culture medium could favor fungal thermotolerance, as well as induced tolerance to UV radiation (Pereira-Junior et al 2018 ), by the increase of proteins responsible for cell repair. In addition to intracellular proteins, possible extracellular components contributing to heat tolerance, since riboflavin increased the expression of genes involved in conidia pigmentation and therefore radiation tolerance (Pereira-Junior et al 2018 ; Lovett and St. Leger 2015 ).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the presence of riboflavin in the culture medium could favor fungal thermotolerance, as well as induced tolerance to UV radiation (Pereira-Junior et al 2018 ), by the increase of proteins responsible for cell repair. In addition to intracellular proteins, possible extracellular components contributing to heat tolerance, since riboflavin increased the expression of genes involved in conidia pigmentation and therefore radiation tolerance (Pereira-Junior et al 2018 ; Lovett and St. Leger 2015 ). With all this in mind, this study demonstrated that the presence of riboflavin and sodium nitrate increased M. robertsii thermotolerance.…”

Section: Discussionmentioning

confidence: 99%

“…Different compounds, such as inorganic salts and vitamins, can influence biomass formation and extracellular enzyme production in certain isolates (Shah et al 2005 ). Studies related to the use of additives for M. robertsii are scarce, one of the most promising being riboflavin—a complex nitrogen source mainly related to cellular oxidative metabolism (Pereira-Junior et al 2018 ). However, studies that determine in detail riboflavin as a potential supplement for M. robertsii culture media are lacking.…”

Section: Introductionmentioning

confidence: 99%

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Metarhizium robertsii protease and conidia production, response to heat stress and virulence against Aedes aegypti larvae

2021

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Nutritional factors exert significant influence on the growth of entomopathogenic fungi, one of the main agents employed commercially in the biological control of arthropods. Thus, the objective of this work is to optimize the culture medium and solid fermentation time for production of proteases and conidia of Metarhizium robertsii ARSEF 2575 and to evaluate the interference of riboflavin and salts on virulence and resistance to abiotic stress factors. In the first step, nine groups were separated: negative control, positive control, and seven supplementation groups: ammonium nitrate, ammonium chloride, potassium nitrate, sodium nitrate, ammonium sulfate, ammonium phosphate, urea. Sodium nitrate showed significant difference in protease production at the time of 20 days of solid fermentation. Then, different concentrations of sodium nitrate and riboflavin as supplement were evaluated. Response surface methodology demonstrated that riboflavin and sodium nitrate influence proteolytic activity and conidia production, but without synergism. Supplementation of the medium with the optimal concentration of sodium nitrate and riboflavin did not interfere with the germination of conidia without exposure to abiotic stress, but did increase the thermotolerance of conidia. The presence of riboflavin and sodium nitrate at optimal concentrations in the culture medium did not alter fungal virulence with and without exposure to heat stress, varying according to the presence or absence of the supernatant during exposure, evidencing that resistance to heat exposure is multifactorial and dependent on intra- and extracellular factors. Moreover, the supplementation increased the larvicidal activity of the supernatant against Aedes aegypti.

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Metarhizium pingshaense photolyase expression and virulence to Rhipicephalus microplus after UV‐B exposure

de Lima,

Fiorotti,

Paulino

et al. 2023

J Basic Microbiol

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The current study examined the impact of ultraviolet (UV)‐B radiation in Metarhizium pingshaense blastospores' photolyase expression and their virulence against Rhipicephalus microplus. Blastospores were exposed to UV under laboratory and field conditions. Ticks were treated topically with fungal suspension and exposed to UV‐B in the laboratory for three consecutive days. The expression of cyclobutane pyrimidine dimmers (CPDs)‐photolyase gene maphr1‐2 in blastospores after UV exposure followed by white light exposure was accessed after 0, 8, 12, 24, 36, and 48 h. Average relative germination of blastospores 24 h after in vitro UV exposure was 8.4% lower than 48 h. Despite this, the relative germination of blastospores exposed to UV in the field 18 h (95.7 ± 0.3%) and 28 h (97.3 ± 0.8%) after exposure were not different (p > 0.05). Ticks treated with fungus and not exposed to UV exhibited 0% survival 10 days after the treatment, while fungus‐treated ticks exposed to UV exhibited 50 ± 11.2% survival. Expression levels of maphr1‐2 8, 12, and 24 h after UV‐B exposure were not different from time zero. Maphr1‐2 expression peak in M. pingshaense blastospores occurred 36 h after UV‐B exposure, in the proposed conditions and times analyzed, suggesting repair mechanisms other than CPD‐mediated‐photoreactivation might be leading blastospores' germination from 0 to 24 h.

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Riboflavin induces Metarhizium spp. to produce conidia with elevated tolerance to UV ‐B, and upregulates photolyases, laccases and polyketide synthases genes

Abstract: The enhanced UV-B tolerance of Metarhizium spp. conidia produced on Rb-enriched media may improve the effectiveness of these fungi in biological control programs.

Cited by 16 publications

References 82 publications

Tolerance to Abiotic Factors of Microsclerotia and Mycelial Pellets From Metarhizium robertsii, and Molecular and Ultrastructural Changes During Microsclerotial Differentiation

Tolerance to Abiotic Factors of Microsclerotia and Mycelial Pellets From Metarhizium robertsii, and Molecular and Ultrastructural Changes During Microsclerotial Differentiation

Metarhizium robertsii protease and conidia production, response to heat stress and virulence against Aedes aegypti larvae

Metarhizium pingshaense photolyase expression and virulence to Rhipicephalus microplus after UV‐B exposure

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