Molecular and physiological effects of environmental UV radiation on fungal conidia

Braga, Gilberto Úbida Leite; Rangel, Drauzio E.N.; Fernandes, Éverton K. K.; Flint, Stephan D.; Roberts, Donald W.

doi:10.1007/s00294-015-0483-0

Cited by 180 publications

(112 citation statements)

References 218 publications

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“…Accordingly, many studies that evaluated the effect of UV radiation on entomopathogenic fungi have calculated the dose based on the Quaite-weighted irradiance rather than on the total irradiance (Fernandes et al 2007;Braga et al 2001a, d;Rangel et al 2004;Nascimento et al 2010). For a more detailed discussion on this subject, see Braga et al (2015) in this issue of Current Genetics.…”

Section: Seeking Fungal Isolates Naturally Tolerant To Uvmentioning

confidence: 98%

Tolerance of entomopathogenic fungi to ultraviolet radiation: a review on screening of strains and their formulation

et al. 2015

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Ultraviolet radiation from sunlight is probably the most detrimental environmental factor affecting the viability of entomopathogenic fungi applied to solar-exposed sites (e.g., leaves) for pest control. Most entomopathogenic fungi are sensitive to UV radiation, but there is great inter- and intraspecies variability in susceptibility to UV. This variability may reflect natural adaptations of isolates to their different environmental conditions. Selecting strains with outstanding natural tolerance to UV is considered as an important step to identify promising biological control agents. However, reports on tolerance among the isolates used to date must be analyzed carefully due to considerable variations in the methods used to garner the data. The current review presents tables listing many studies in which different methods were applied to check natural and enhanced tolerance to UV stress of numerous entomopathogenic fungi, including several well-known isolates of these fungi. The assessment of UV tolerance is usually conducted with conidia using dose-response methods, wherein the UV dose is calculated simply by multiplying the total irradiance by the period (time) of exposure. Although irradiation from lamps seldom presents an environmentally realistic spectral distribution, laboratory tests circumvent the uncontrollable circumstances associated with field assays. Most attempts to increase field persistence of microbial agents have included formulating conidia with UV protectants; however, in many cases, field efficacy of formulated fungi is still not fully adequate for dependable pest control.

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Section: Seeking Fungal Isolates Naturally Tolerant To Uvmentioning

confidence: 98%

Tolerance of entomopathogenic fungi to ultraviolet radiation: a review on screening of strains and their formulation

et al. 2015

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“…Environmental conditions during conidiation affect the physiological properties, such as morphology, germination kinetics, and pathogenicity, of spores from other fungi [17–20]. In addition, entomopathogenic fungi have demonstrated that virulence toward insect hosts, and conidial tolerance to heat and UV radiation, are greatly influenced by environmental conditions such as the medium, water activity, light illumination, and oxygen concentration, during conidia production [21,22]. Thus, environmental conditions appear to be key factors that affect fungal conidial properties; however, little is known about the impacts of temperature on the properties of the conidia of Aspergillus species, including the medically important pathogenic fungus A .…”

Section: Introductionmentioning

confidence: 99%

Temperature during conidiation affects stress tolerance, pigmentation, and trypacidin accumulation in the conidia of the airborne pathogen Aspergillus fumigatus

et al. 2017

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Asexual spores (conidia) are reproductive structures that play a crucial role in fungal distribution and survival. As fungal conidia are, in most cases, etiological agents of plant diseases and fungal lung disease, their stress resistance and interaction with their hosts have drawn increasing attention. In the present study, we investigated whether environmental temperature during conidiation affects the stress tolerance of the conidia of the human pathogenic fungus Aspergillus fumigatus. Conidia from a 25°C culture showed a lower tolerance to heat (60°C) and oxidative (H2O2) stresses and a marked resistance to ultraviolet radiation exposure, compared with those produced at 37 and 45°C. The accumulation of trehalose was lower in the conidia from the 25°C culture. Furthermore, the conidia from the 25°C culture showed darker pigmentation and increased transcripts of dihydroxynaphthalene (DHN)-melanin biosynthesis-related genes (i.e., pksP, arp1, and arp2). An RNA-sequencing analysis revealed that the transcription level of the trypacidin (tpc) gene cluster, which contains 13 genes, was sharply and coordinately activated in the conidia from the 25°C culture. Accordingly, trypacidin was abundant in the conidia from the 25°C culture, whereas there was little trypacidin in the conidia from the 37°C culture. Taken together, these data show that the environmental temperature during conidiation affects conidial properties such as stress tolerance, pigmentation, and mycotoxin accumulation. To enhance our knowledge, we further explored the temperature-dependent production of DHN-melanin and trypacidin in clinical A. fumigatus isolates. Some of the isolates showed temperature-independent production of DHN-melanin and/or trypacidin, indicating that the conidia-associated secondary metabolisms differed among the isolates.

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“…Accordingly, most fungi show light‐induced expression of defense genes which protect against or repair such lesions, and formation of pigments which filter visible light and/or UV (Braga et al. ).…”

Section: Introductionmentioning

confidence: 99%

White collar 1‐induced photolyase expression contributes to UV ‐tolerance of Ustilago maydis

et al. 2015

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Ustilago maydis is a phytopathogenic fungus causing corn smut disease. It also is known for its extreme tolerance to UV‐ and ionizing radiation. It has not been elucidated whether light‐sensing proteins, and in particular photolyases play a role in its UV‐tolerance. Based on homology analysis, U. maydis has 10 genes encoding putative light‐responsive proteins. Four amongst these belong to the cryptochrome/photolyase family (CPF) and one represents a white collar 1 ortholog (wco1). Deletion mutants in the predicted cyclobutane pyrimidine dimer CPD‐ and (6–4)‐photolyase were impaired in photoreactivation. In line with this, in vitro studies with recombinant CPF proteins demonstrated binding of the catalytic FAD cofactor, its photoreduction to fully reduced FADH − and repair activity for cyclobutane pyrimidine dimers (CPDs) or (6–4)‐photoproducts, respectively. We also investigated the role of Wco1. Strikingly, transcriptional profiling showed 61 genes differentially expressed upon blue light exposure of wild‐type, but only eight genes in the Δwco1 mutant. These results demonstrate that Wco1 is a functional blue light photoreceptor in U. maydis regulating expression of several genes including both photolyases. Finally, we show that the Δwco1 mutant is less tolerant against UV‐B due to its incapability to induce photolyase expression.

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Molecular and physiological effects of environmental UV radiation on fungal conidia

Cited by 180 publications

References 218 publications

Tolerance of entomopathogenic fungi to ultraviolet radiation: a review on screening of strains and their formulation

Tolerance of entomopathogenic fungi to ultraviolet radiation: a review on screening of strains and their formulation

Temperature during conidiation affects stress tolerance, pigmentation, and trypacidin accumulation in the conidia of the airborne pathogen Aspergillus fumigatus

White collar 1‐induced photolyase expression contributes to UV ‐tolerance of Ustilago maydis

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