Caracterização de fungos do gênero Purpureocillium provenientes de amostras de solo do Estado do Rio Grande do Sul

O controle de pragas consiste no manejo de espécies que causam prejuízos à agricultura e/ou oferecem risco à saúde humana. Nos últimos anos o controle biológico, que utiliza organismos vivos para controlar espécies danosas à variadas atividades, desde aquelas de importância agrícola até fitossanitária, vêm ganhando relevância como alternativa ao controle químico tradicional. Dentre os microrganismos, os fungos entomopatogênicos se destacam por apresentar um importante papel no controle natural da população de artrópodes. Fungos do gênero Purpureocillium vêm recebendo crescente interesse devido às muitas aplicações biotecnológicas em potencial, dentre elas: indução do crescimento vegetal, atividade nematicida, produção de metabólitos secundários e controle biológico de artrópodes. Idealmente, espécies aplicáveis ao controle biológico de artrópodes devem apresentar, além de alta virulência a seus hospedeiros, elevada tolerância a estresses abióticos, como temperatura e radiação ultravioleta. Um dos principais obstáculos ao uso disseminado das espécies deste gênero consiste na falta de dados sobre o quão resilientes as mesmas são a estresses abióticos, bem como do papel ambiental exercido pelo gênero. Neste sentido, este trabalho tem como objetivos avaliar a virulência e o crescimento em diferentes faixas de temperatura de isolados de Purpureocillium spp., derivados de amostras de solo do estado do Rio Grande do Sul. Os isolados, pertencentes à coleção de fungos entomopatogênicos do Laboratório de Biologia Celular e Molecular de Fungos Filamentos, foram identificados por análise de estruturas macro e microscópicas, além da análise das sequências de rDNA-ITS. Os resultados obtidos revelaram que a temperatura ideal de crescimento de Purpureocillium spp. está na faixa de 28 ºC, com crescimento reduzido a 22 ºC e 37 ºC, observando-se inibição total do crescimento a 12 ºC. Os bioensaios realizados, até o presente momento, empregando larvas de Tenebrio molitor, mostraram que, majoritariamente, os fungos apresentaram um tempo letal de 50% de 12 dias. As linhagens AS4, AS115, AS224, AS254 e AS259 se mostraram as mais virulentas e, portanto, as mais promissoras, com LT50 de entre 6 e 7 dias. As perspectivas incluem a realização de testes para avaliar a resistência dos isolados a radiação UV. Por fim, a seleção dos isolados com maior potencial controlador biológico para bioensaios contra a lagarta-do-cartucho Spodoptera frugiperda.Pest control consists of the management of species that cause damage to agriculture and / or pose a risk to human health. In recent years, biological control, which uses living organisms to control species harmful to many activities, ranging from those of agricultural importance to those of fitosanitary relevance, has gained relevance as an alternative to traditional chemical control. Among microorganisms, entomopathogenic fungi are a group of special interest, as they play an important role in the natural control of the arthropod population. Fungi of the genus Purpureocillium have been receiving increasing interest due to their many potential biotechnological applications, such as: induction of plant growth, nematicidal activity, production of secondary metabolites and biological control of arthropods. Ideally, species applicable to the biological control of arthropods should present, in addition to high virulence to their hosts, high tolerance to abiotic stresses, such as temperature and ultraviolet radiation. One of the main obstacles to the widespread use of species of this genus is the lack of data on how resilient they are to abiotic stresses as well as the environmental role played by this genus. In this sense, this work aims to evaluate virulence and growth in different temperature ranges, as well as to test the resistance to UV radiation of Purpureocillium spp. isolates, derived from soil samples from the state of Rio Grande do Sul. The isolates, which belong to the collection of entomopathogenic fungi of the Laboratory of Cellular and Molecular Biology of Filamentous Fungi, were identified by analysis of macro and microscopic structures, in addition to the analysis of the rDNA-ITS sequences. The results obtained reveal that the ideal growth temperature for Purpureocillium spp. is in the range of 28 ºC, with reduced growth at 22 ºC and 37 ºC, and with total growth inhibition at 12 ºC. The bioassays carried out, so far, using larvae of Tenebrio molitor, showed that, mainly, the fungi had an average lethal time of 50% of 12 days. The strains AS4, AS115, AS224, AS254 and AS259 proved to be the most virulent and, therefore, the most promising, with LT50 between 6 and 7 days. Future prospects include conducting tests to assess the resistance of the isolates to UV radiation. Also, to select the isolates with the greatest potential of biological control to be tested on bioassays against the Fall Armyworm Spodoptera frugiperda larvae

Caracterização de fungos do gênero purpureocillium provenientes de amostras de solo do Estado do Rio Grande do Sul

O controle de pragas consiste no manejo de espécies que causam prejuízos à agricultura e/ou oferecem risco à saúde humana. Nos últimos anos o controle biológico, que utiliza organismos vivos para controlar espécies danosas à variadas atividades, desde aquelas de importância agrícola até fitossanitária, vêm ganhando relevância como alternativa ao controle químico tradicional. Dentre os microrganismos, os fungos entomopatogênicos se destacam por apresentar um importante papel no controle natural da população de artrópodes. Fungos do gênero Purpureocillium vêm recebendo crescente interesse devido às muitas aplicações biotecnológicas em potencial, dentre elas: indução do crescimento vegetal, atividade nematicida, produção de metabólitos secundários e controle biológico de artrópodes. Idealmente, espécies aplicáveis ao controle biológico de artrópodes devem apresentar, além de alta virulência a seus hospedeiros, elevada tolerância a estresses abióticos, como temperatura e radiação ultravioleta. Um dos principais obstáculos ao uso disseminado das espécies deste gênero consiste na falta de dados sobre o quão resilientes as mesmas são a estresses abióticos, bem como do papel ambiental exercido pelo gênero. Neste sentido, este trabalho tem como objetivos avaliar a virulência e o crescimento em diferentes faixas de temperatura de isolados de Purpureocillium spp., derivados de amostras de solo do estado do Rio Grande do Sul. Os isolados, pertencentes à coleção de fungos entomopatogênicos do Laboratório de Biologia Celular e Molecular de Fungos Filamentos, foram identificados por análise de estruturas macro e microscópicas, além da análise das sequências de rDNA-ITS. Os resultados obtidos revelaram que a temperatura ideal de crescimento de Purpureocillium spp. está na faixa de 28 ºC, com crescimento reduzido a 22 ºC e 37 ºC, observando-se inibição total do crescimento a 12 ºC. Os bioensaios realizados, até o presente momento, empregando larvas de Tenebrio molitor, mostraram que, majoritariamente, os fungos apresentaram um tempo letal de 50% de 12 dias. As linhagens AS4, AS115, AS224, AS254 e AS259 se mostraram as mais virulentas e, portanto, as mais promissoras, com LT50 de entre 6 e 7 dias. As perspectivas incluem a realização de testes para avaliar a resistência dos isolados a radiação UV. Por fim, a seleção dos isolados com maior potencial controlador biológico para bioensaios contra a lagarta-do-cartucho Spodoptera frugiperda.Pest control consists of the management of species that cause damage to agriculture and / or pose a risk to human health. In recent years, biological control, which uses living organisms to control species harmful to many activities, ranging from those of agricultural importance to those of fitosanitary relevance, has gained relevance as an alternative to traditional chemical control. Among microorganisms, entomopathogenic fungi are a group of special interest, as they play an important role in the natural control of the arthropod population. Fungi of the genus Purpureocillium have been receiving increasing interest due to their many potential biotechnological applications, such as: induction of plant growth, nematicidal activity, production of secondary metabolites and biological control of arthropods. Ideally, species applicable to the biological control of arthropods should present, in addition to high virulence to their hosts, high tolerance to abiotic stresses, such as temperature and ultraviolet radiation. One of the main obstacles to the widespread use of species of this genus is the lack of data on how resilient they are to abiotic stresses as well as the environmental role played by this genus. In this sense, this work aims to evaluate virulence and growth in different temperature ranges, as well as to test the resistance to UV radiation of Purpureocillium spp. isolates, derived from soil samples from the state of Rio Grande do Sul. The isolates, which belong to the collection of entomopathogenic fungi of the Laboratory of Cellular and Molecular Biology of Filamentous Fungi, were identified by analysis of macro and microscopic structures, in addition to the analysis of the rDNA-ITS sequences. The results obtained reveal that the ideal growth temperature for Purpureocillium spp. is in the range of 28 ºC, with reduced growth at 22 ºC and 37 ºC, and with total growth inhibition at 12 ºC. The bioassays carried out, so far, using larvae of Tenebrio molitor, showed that, mainly, the fungi had an average lethal time of 50% of 12 days. The strains AS4, AS115, AS224, AS254 and AS259 proved to be the most virulent and, therefore, the most promising, with LT50 between 6 and 7 days. Future prospects include conducting tests to assess the resistance of the isolates to UV radiation. Also, to select the isolates with the greatest potential of biological control to be tested on bioassays against the Fall Armyworm Spodoptera frugiperda larvae

MÉTODO DA GOTA DE EXSUDAÇÃO VERSUS GRAVIMETRIA DE RESINA EM BRAQUIBLASTOS: VALIDAÇÃO DE INDICADORES DE SELEÇÃO PRECOCE PARA CAPACIDADE RESINÍFERA DE Pinus elliottii ENGELM

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Microcutting redox profile and anatomy in Eucalyptus spp. With distinct adventitious rooting competence

Adventitious root (AR) development takes place in an intricate cellular environment. Reactive oxygen species (ROS) and antioxidant defenses, triggered by wounding in cuttings, can modulate this process. A comparative assessment of biochemical and anatomical parameters at critical rooting stages in hard- (Eucalyptus globulus Labill.) and easy- (Eucalyptus grandis W.Hill ex Maiden) to-root species was carried out. Microcuttings from seedlings were inoculated in auxin-free AR induction medium and, after 96 h, transferred to AR formation medium for a period of 24 h. Samples were collected upon excision (Texc) and at the 5th day post excision (Tform). Delayed xylem development, with less lignification, was recorded in E. globulus, when compared to E. grandis, suggesting lower activity of the cambium layer, an important site for AR development. Superoxide was more densely present around the vascular cylinder at both sampled times, and in greater quantity in E. globulus than E. grandis, declining with time in the former. Hydrogen peroxide was localized primarily along cell walls, more intensely in the primary xylem and phloem, and increased significantly at Tform in E. globulus. Ascorbate peroxidase (APX), superoxide dismutase (SOD), and catalase (CAT) activities were generally higher in E. grandis and varied as a function of time in E. globulus. Soluble guaiacol peroxidase (GPRX) activity increased from Texc to Tform in both species, whereas cell wall-bound GPRX activity increased with time in E. grandis, surpassing E. globulus. Flavonoid content increased with time in E. grandis and was higher than E. globulus at Tform. Principal component analysis showed that species- and time-derived differences contributed to almost 80% of the variance. Overall, data indicate that E. grandis shows higher cambium activity and tighter modulation of redox conditions than E. globulus. These features may influence ROS-based signaling and phytohormone homeostasis of cuttings, thereby impacting on AR development. Besides being players in the realm of AR developmental differences, the specific features herein identified could become potential tools for early clone selection and AR modulation aiming at improved clonal propagation of this forest crop

MÉTODO DA GOTA DE EXSUDAÇÃO VERSUS GRAVIMETRIA DE RESINA EM BRAQUIBLASTOS: VALIDAÇÃO DE INDICADORES DE SELEÇÃO PRECOCE PARA CAPACIDADE RESINÍFERA DE Pinus elliottii ENGELM

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