Metarhizium robertsii and M. acridum conidia produced on riboflavin-supplemented medium have increased UV-A tolerance and upregulated photoprotection and photoreactivation genes

The aim of this study was to evaluate the effect of riboflavin supplementation of culture medium on conidial UV-A tolerance of M. acridum (Driver & Milner) (Hypocreales: Clavicipitaceae) and M. robertsii (Bischoff, Rehner & Humber) (Hypocreales: Clavicipitaceae). These fungi were produced on culture medium supplemented, or not supplemented, with riboflavin. Relative germination and expression patterns of some photoprotection-related genes were evaluated after irradiating with artificial UV-A, or with filtered solar radiation (> 320 nm; UV-A and visible radiation). M. acridum conidia harvested from riboflavin-supplemented culture medium demonstrated enhanced UV-A tolerance when irradiated with artificial UV-A. Nevertheless, relative germination of conidia of both species produced on riboflavin-supplemented medium and exposed to filtered solar radiation was significantly higher than those produced on medium not supplemented with riboflavin. Riboflavin increased the transcription of photolyases, laccases and polyketide synthase genes. However, each fungal species induced different genes patterns involved in DNA repair and photoprotection. The addition of riboflavin to the substrate used for mass production of Metarhizium spp. and the resulting enhancement of conidial tolerance to solar radiation may improve the effectiveness of these fungi in biological control programs.Instituto de Investigaciones Bioquímicas de La Plat

The Third International Symposium on Fungal Stress – ISFUS

Stress is a normal part of life for fungi, which can survive in environments considered inhospitable or hostile for other organisms. Due to the ability of fungi to respond to, survive in, and transform the environment, even under severe stresses, many researchers are exploring the mechanisms that enable fungi to adapt to stress. The International Symposium on Fungal Stress (ISFUS) brings together leading scientists from around the world who research fungal stress. This article discusses presentations given at the third ISFUS, held in São José dos Campos, São Paulo, Brazil in 2019, thereby summarizing the state-of-the-art knowledge on fungal stress, a field that includes microbiology, agriculture, environmental science, ecology, biotechnology, medicine, and astrobiology

Estimates of genetic parameters related to chitinase production by the entomopathogenic fungus Metarhizium anisopliae

Chitinolytic activity and dry mass production were determined in culture filtrates from 17 Metarhizium anisopliae strains grown in liquid medium containing chitin as the only carbon source. The objectives were to estimate parameters such as genetic variance among strains, heritability and expected gain from selection, as well as correlations between tested traits. Wide genotypic variability was observed among strains in chitinolytic activity, permitting the exploitation of this property in selection. The high heritability suggests that progress can be made through phenotypic selection. The genotypic correlation coefficient between dry mass production and chitinolytic activity detected in the filtrates was negative (= - 0.588). One of the isolates was also investigated for variation in the two traits as a function of culture growth time. The results showed an increase in enzyme activity up to the 8th (and last) day of the experiment and a decrease in dry mass from the 4th day on.Foi determinada a atividade quitinolítica apresentada pelos filtrados de culturas de 17 genótipos de Metarhizium anisopliae crescidos em meio líquido, tendo quitina como única fonte de carbono. O objetivo foi a estimativa de parâmetros como a variância genética, a herdabilidade e o ganho esperado na seleção. Uma grande variabilidade genotípica foi verificada na atividade quitinolítica, permitindo sua exploração no melhoramento. Os altos coeficientes de herdabilidade permitem esperar um grande progresso na seleção fenotípica. Para uma das linhagens foi também determinada a variação na atividade enzimática, em função do tempo de crescimento das culturas. Os resultados mostraram um aumento na atividade enzimática até o oitavo dia da avaliação.171177Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Outcome of blue, green, red, and white light on Metarhizium robertsii during mycelial growth on conidial stress tolerance and gene expression

Fungi sense light and utilize it as a source of environmental information to prepare against many stressful conditions in nature. In this study, Metarhizium robertsii was grown on: 1) potato dextrose agar medium (PDA) in the dark (control); 2) under nutritive stress in the dark; and 3) PDA under continuous (A) white light; (B) blue light lower irradiance = LI; (C) blue light higher irradiance = HI; (D) green light; and (E) red light. Conidia produced under these treatments were tested against osmotic stress and UV radiation. In addition, a suite of genes usually involved in different stress responses were selected to study their expression patterns. Conidia produced under nutritive stress in the dark were the most tolerant to both osmotic stress and UV radiation, and the majority of their stress- and virulence-related genes were up-regulated. For osmotic stress tolerance, conidia produced under white, blue LI, and blue HI lights were the second most tolerant, followed by conidia produced under green light. Conidia produced under red light were the least tolerant to osmotic stress and less tolerant than conidia produced on PDA medium in the dark. For UV tolerance, conidia produced under blue light LI were the second most tolerant to UV radiation, followed by the UV tolerances of conidia produced under white light. Conidia produced under blue HI, green, and red lights were the least UV tolerant and less tolerant than conidia produced in the dark. The superoxide dismutases (sod1 and sod2), photolyases (6-4phr and CPDphr), trehalose-phosphate synthase (tps), and protease (pr1) genes were highly up-regulated under white light condition, suggesting a potential role of these proteins in stress protection as well as virulence after fungal exposure to visible spectrum components.Fil: Dias, Luciana P.. Universidade de Sao Paulo; BrasilFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Braga, Gilberto U.L.. Universidade de Sao Paulo; BrasilFil: Ferreira, Paulo C.. Universidade de Sao Paulo; BrasilFil: Pupin, Breno. Universidade do Vale do Paraíba; BrasilFil: Araújo, Claudinéia A.S.. Universidade do Vale do Paraíba; BrasilFil: Corrochano, Luis M.. Universidad de Sevilla; EspañaFil: Rangel, Drauzio E.N.. Universidade Brasil; Brasi

Metarhizium robertsii and M. acridum conidia produced on riboflavin-supplemented medium have increased UV-A tolerance and upregulated photoprotection and photoreactivation genes

The aim of this study was to evaluate the effect of riboflavin supplementation of culture medium on conidial UV-A tolerance of M. acridum (Driver & Milner) (Hypocreales: Clavicipitaceae) and M. robertsii (Bischoff, Rehner & Humber) (Hypocreales: Clavicipitaceae). These fungi were produced on culture medium supplemented, or not supplemented, with riboflavin. Relative germination and expression patterns of some photoprotection-related genes were evaluated after irradiating with artificial UV-A, or with filtered solar radiation (> 320 nm; UV-A and visible radiation). M. acridum conidia harvested from riboflavin-supplemented culture medium demonstrated enhanced UV-A tolerance when irradiated with artificial UV-A. Nevertheless, relative germination of conidia of both species produced on riboflavin-supplemented medium and exposed to filtered solar radiation was significantly higher than those produced on medium not supplemented with riboflavin. Riboflavin increased the transcription of photolyases, laccases and polyketide synthase genes. However, each fungal species induced different genes patterns involved in DNA repair and photoprotection. The addition of riboflavin to the substrate used for mass production of Metarhizium spp. and the resulting enhancement of conidial tolerance to solar radiation may improve the effectiveness of these fungi in biological control programs.Fil: Huarte Bonnet, Carla. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Pereira Junior, Ronaldo A.. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Santos Da Paixao, Flavia Regina. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Braga, Gilberto U.L.. Universidade de Sao Paulo; BrasilFil: Roberts, Donald W.. State University of Utah; Estados UnidosFil: Luz, Christian. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; BrasilFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Fernandes, Éverton. Universidade Federal de Goias. Instituto de Patologia Tropical E Saude Publica.; Brasi

Protease production during growth and autolysis of submerged Metarhizium anisopliae cultures Produção de protease durante o crescimento e análise de culturas submersas de Metarhizium anisopliae

The growth and autolysis of two strains of the entomopathogenic deuteromycete fungus Metarhizium anisopliae var. anisopliae were evaluated in medium containing casein or glucose as carbon source. Parameters such as economic coefficient and degree of autolysis were determined for each strain. Protease production was determined throughout the growth and autolysis phases of the cultures on medium under conditions of protease induction (in the presence of casein as sole source of carbon and nitrogen). The fungus was shown to utilize casein as a carbon/energy source in a more efficient manner than glucose. The autolysis shown by the strains was intense under both types of growth conditions, reaching up to 62.7% of the dry mass produced and started soon after the depletion of the exogenous carbon source. The relationship between the proteolytic activities of the two strains evaluated varied significantly (a maximum of 19.78 on the 5th day and a minimum of 2.03 on the 16th day of growth) during the various growth and autolysis phases, clearly showing that the difference between the growth curves and the difference in the kinetics of enzyme production may decisively affect the process of strain selection for protease production.<br>O crescimento e a autólise de duas linhagens do deuteromiceto entomopatogênico Metarhizium anisopliae var. anisopliae foram avaliados em meio contendo caseína ou glicose como fonte de carbono. Foram determinados parâmetros como o coeficiente econômico e o grau de autólise apresentado pelas linhagens. A produção de protease foi determinada durante todas as fases do crescimento e da autólise das culturas, em meio indutor da produção de proteases (meio contendo caseína como única fonte de carbono e de nitrogênio). Pôde-se verificar que o fungo foi capaz de utilizar a caseína como fonte de carbono/energia de maneira mais eficiente do que a glicose. A autólise apresentada pelas linhagens foi intensa em ambas as condições de crescimento, alcançando até 62,7% da massa seca produzida, e se iniciou logo após o esgotamento da fonte exógena de carbono. A relação entre as atividades proteolíticas apresentadas pelas duas linhagens avaliadas variou de maneira significativa (máxima de 19,78 no 5° dia e mínima de 1,55 no 16° dia de incubação) durante as diversas fases do crescimento e da autólise, deixando claro que as diferenças verificadas entre as curvas de crescimento e entre as cinéticas da produção das enzimas podem influenciar decisivamente no processo de seleção de linhagens para a produção de proteases