Cassava is one of the most important crops in Africa, Asia and Latin America, where millions of people depend on its starchy storage roots as their main source of energy. In Brazil, cassava is ...cultivated in all regions; however, soft root rot disease has hampered its production mainly in the Amazon region. The identification of Phytopythium sp., as the causal agent of soft root rot disease in cassava plants collected in Brazil, was recently reported. Here, our main aim was to evaluate changes in expression levels of genes possibly involved in compatible cassava- Phytopythium sp. interaction. Semi-quantitative RT-PCR assays were performed to evaluate the expression levels of genes coding for proteins with known functions in plant defense, such as enzymes involved in oxidative burst and the phenylpropanoid pathway, in detached cassava storage roots inoculated and non-inoculated with pathogen. Our results showed that cassava responded to pathogen infection through up-regulation of genes coding for superoxide dismutase, phenylalanine ammonia-lyase, chalcone synthase, cysteine proteinase inhibitor and RING zinc finger protein. Furthermore, the expression pattern of the allergenic-related glutamic acid-rich protein and translationally controlled tumor protein genes in detached roots used here validated the absence of post-harvest physiological deterioration, a known endogenous disorder affecting the storage roots of cassava at 24–72 h after harvest. This is the first study of interaction between cassava and Phytopythium sp. at the molecular level contributing to understanding how cassava responds to pathogen infection, as well as to future strategies of molecular breeding regarding the tolerance to soft root rot disease.
•Detached storage roots of susceptible cassava (CPATU 359) were used in interaction study with Phytopythium sp. causing soft root rot disease.•Seven defense genes were up-regulated in cassava roots infected by Phytopythium sp., such as superoxide dismutase, phenylalanine ammonia-lyase and chalcone synthase.•The absence of post-harvest physiological deterioration in detached roots of cassava was validated at the molecular level.
Cassava (Manihot esculenta Crantz) is an important crop in Brazil and Pará is the major producer of roots. High temperature and humidity of tropical regions favor the development of various diseases, ...among them the cassava root rot. The objective of this study was to evaluate the effect of luminosity and culture medium on the mycelial growth and sporulation of Phytopythium sp. associated with different methods of inoculation on cassava roots. In vitro tests for pathogen growth were established in a 2 x 6 factorial design (luminosity x culture medium) with five replicates and the means were compared by t test (P≤0.05). The culture medium containing sweet cassava root produced greater mycelial development and higher pathogen sporulation and it was the most suitable medium for pathogen culture. The culture under absence of light generated better mycelial growth than culture under 12 hour of light. Regarding the type of inoculation, the response was better when deeper injuries were induced.
RESUMO: A mandioca (Manihot esculenta Crantz) é uma importante cultura para o Brasil, onde o Pará é o principal produtor de raízes. Regiões tropicais com alta umidade e temperatura favorecem o desenvolvimento de diversas doenças, como as podridões de raiz. O presente estudo tem como objetivo avaliar o efeito da luminosidade e de meios de cultura no crescimento micelial e na esporulação de Phytopythium sp. e analisar métodos de inoculação do patógeno em raízes de mandioca destacadas. Os ensaios in vitro foram instalados em esquema fatorial 2x6 (luminosidade x meio de cultura), com cinco repetições e as médias comparadas pelo teste t (p≤0,05). O meio de cultura contendo raiz de mandioca mansa proporcionou maior desenvolvimento micelial e maior esporulação do patógeno e é o mais adequado para o cultivo do patógeno. O cultivo sob ausência de luz gerou melhor crescimento micelial do que o cultivo sob 12 horas de luz. Quanto ao tipo de inoculação, a resposta foi melhor nas raízes que obtiveram ferimentos mais profundos.
Over the last few years, considerable effort has been spent by Embrapa in the construction of a plant disease database representative enough for the development of effective methods for automatic ...plant disease detection and recognition. In October of 2016, this database, called PDDB, had 2326 images of 171 diseases and other disorders affecting 21 plant species. PDDB size, although considerable, is not enough to allow the use of powerful techniques such as deep learning. In order to increase its size, each image was subdivided according to certain criteria, increasing the number of images to 46,513. Both the original (PDDB) and subdivided (XDB) databases are now being made freely available for academic research purposes, thus supporting new studies and contributing to speed up the advances in the area. Both collections are expected to grow continuously in order to expand their reach. PDDB and XDB can be accessed in the link https://www.digipathos-rep.cnptia.embrapa.br/.
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•Phylloplane bacteria were effective in reducing the bacterial blight severity.•Iron and nitrogenate compounds competition explains bacterial blight control.•Disease control ability ...is not related to antibiosis nor to resistance induction.•Siderophore-producing organisms may lead to a false-positive result for antibiosis.
The knowledge of biological control mechanism that provides a significant reduction in disease severity can guide the screening procedures and allow the discovery of new possibilities for disease control. In this study, a reduction of bacterial blight severity, caused by three Xanthomonas axonopodis pv. passiflorae (Xap) strains, was demonstrated by using nine indigenous passionfruit phylloplane bacteria regardless of the pathogen origin. Experiments were done to elucidate preemptive exclusion through carbon sources utilization profiles, siderophores production, iron competition and antibiosis. Furthermore, peroxidase activity and spatial separation assays were conducted to evaluate the ability to induce systemic resistance. Identification by 16S rRNA gene sequencing revealed that nine phylloplane strains show highest similarity to Arthrobacter, Curtobacterium, Enterobacter, Microbacterium, Pseudomonas or Stenotrophomonas. It is concluded that competition for iron and nitrogenate compounds on leaves explains the ability of bacterial phylloplane antagonists to control the disease. For siderophore-producing organisms that present antibiosis evidence, complementary iron supplementation assay is mandatory, to avoid misinterpretation. Results suggest that lack of these compounds could limit the optimal conditions for phylloplane colonization by Xap along the infection process.
Cassava (Manihot esculenta Crantz) is an important crop in Brazil and Para is the major producer of roots. High temperature and humidity of tropical regions favor the development of various diseases, ...among them the cassava root rot. The objective of this study was to evaluate the effect of luminosity and culture medium on the mycelial growth and sporulation of Phytopythium sp. associated with different methods of inoculation on cassava roots. In vitro tests for pathogen growth were established in a 2 x 6 factorial design (luminosity x culture medium) with five replicates and the means were compared by t test (P less than or equal to 0.05). The culture medium containing sweet cassava root produced greater mycelial development and higher pathogen sporulation and it was the most suitable medium for pathogen culture. The culture under absence of light generated better mycelial growth than culture under 12 hour of light. Regarding the type of inoculation, the response was better when deeper injuries were induced. Key words: oomycete, sporulation, mycelium. A mandioca (Manihot esculenta Crantz) e uma importante cultura para o Brasil, onde o Para e o principal produtor de raizes. Regioes tropicais com alta umidade e temperatura favorecem o desenvolvimento de diversas doencas, como as podridoes de raiz. O presente estudo tem como objetivo avaliar o efeito da luminosidade e de meios de cultura no crescimento micelial e na esporulacao de Phytopythium sp. e analisar metodos de inoculacao do patogeno em raizes de mandioca destacadas. Os ensaios in vitro foram instalados em esquema fatorial 2x6 (luminosidade x meio de cultura), com cinco repeticoes e as medias comparadas pelo teste t (p greater than or equal to 05). O meio de cultura contendo raiz de mandioca mansa proporcionou maior desenvolvimento micelial e maior esporulacao do patogeno e e o mais adequado para o cultivo do patogeno. O cultivo sob ausencia de luz gerou melhor crescimento micelial do que o cultivo sob 12 horas de luz. Quanto ao tipo de inoculacao, a resposta foi melhor nas raizes que obtiveram ferimentos mais profundos. Palavras-chave: meio de cultura, oomiceto, esporulacao, micelio.
Rizobactérias no controle da mancha angular do algodoeiro Ishida, Alessandra Keiko Nakasone(Fitopatologia Embrapa Pavilhão de Pesquisa); Souza, Ricardo Magela de(Universidade Federal de Lavras Departamento de Fitopatologia); Resende, Mário Lúcio Vilela de(Universidade Federal de Lavras Departamento de Fitopatologia) ...
Ciência e Agrotecnologia,
02/2008, Letnik:
32, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Avaliou-se o potencial de rizobactérias na indução de resistência do algodoeiro à Xanthomonas axonopodis pv. malvacearum. Após o isolamento das rizobactérias, foram selecionados os isolados capazes ...de reduzir os sintomas da mancha angular bacteriana em casa de vegetação, os quais foram aplicados espacialmente separados do patógeno desafiador. Os melhores isolados foram testados quanto à capacidade de reduzir os sintomas da ramulose e da murcha de Verticillium e de inibir diretamente os patógenos in vitro. Do total de 123 isolados de rizobactérias foram selecionados cinco, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) e MT5-11 (Brevibacterium sp.), os quais apresentaram controle da mancha angular acima de 40%, em relação à testemunha. Nenhum isolado reduziu a severidade da ramulose e da murcha de Verticillium em relação à testemunha, nem apresentou efeito inibitório direto in vitro a X. axonopodis pv. malvacearum e Colletotrichum gossypii var. cephalosporioides. Para V. dahliae, apenas o isolado L2-1 apresentou efeito inibitório.
The potential of rhizobacteria was evaluated for resistance induction against Xanthomonas axonopodis pv. malvacearum. After isolation, the rhizobacteria were screened for the reduction of angular leaf spot severity under greenhouse conditions. They were spatially separated from the challenging pathogen. The best isolates were tested for the capacity to reduce ramulose and Verticillium wilt severity and directly inhibit pathogens in vitro. From a total of 123 rhizobacterial isolates, five were selected, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) and MT5-11 (Brevibacterium sp.), which showed angular leaf spot control above 40% as compared to the control. The tested isolates neither reduced the severity of ramulose and verticillium wilt compared to the control nor showed in vitro direct inhibition to X. axonopodis pv. malvacearum and Colletotrichum gossypii var. cephalosporioides. For V. dahliae, only isolate L2-1 showed direct inhibition.
Avaliou-se o potencial de rizobactérias na indução de resistência do algodoeiro à Xanthomonas axonopodis pv. malvacearum. Após o isolamento das rizobactérias, foram selecionados os isolados capazes ...de reduzir os sintomas da mancha angular bacteriana em casa de vegetação, os quais foram aplicados espacialmente separados do patógeno desafiador. Os melhores isolados foram testados quanto à capacidade de reduzir os sintomas da ramulose e da murcha de Verticillium e de inibir diretamente os patógenos in vitro. Do total de 123 isolados de rizobactérias foram selecionados cinco, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) e MT5-11 (Brevibacterium sp.), os quais apresentaram controle da mancha angular acima de 40%, em relação à testemunha. Nenhum isolado reduziu a severidade da ramulose e da murcha de Verticillium em relação à testemunha, nem apresentou efeito inibitório direto in vitro a X. axonopodis pv. malvacearum e Colletotrichum gossypii var. cephalosporioides. Para V. dahliae, apenas o isolado L2-1 apresentou efeito inibitório.The potential of rhizobacteria was evaluated for resistance induction against Xanthomonas axonopodis pv. malvacearum. After isolation, the rhizobacteria were screened for the reduction of angular leaf spot severity under greenhouse conditions. They were spatially separated from the challenging pathogen. The best isolates were tested for the capacity to reduce ramulose and Verticillium wilt severity and directly inhibit pathogens in vitro. From a total of 123 rhizobacterial isolates, five were selected, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) and MT5-11 (Brevibacterium sp.), which showed angular leaf spot control above 40% as compared to the control. The tested isolates neither reduced the severity of ramulose and verticillium wilt compared to the control nor showed in vitro direct inhibition to X. axonopodis pv. malvacearum and Colletotrichum gossypii var. cephalosporioides. For V. dahliae, only isolate L2-1 showed direct inhibition.
Rizobactérias no controle da mancha angular do algodoeiro Ishida, Alessandra Keiko Nakasone; Souza, Ricardo Magela de; Resende, Mário Lúcio Vilela de ...
Ciência e agrotecnologia,
02/2008, Letnik:
32, Številka:
1
Journal Article
Recenzirano
Avaliou-se o potencial de rizobactérias na indução de resistência do algodoeiro à Xanthomonas axonopodis pv. malvacearum. Após o isolamento das rizobactérias, foram selecionados os isolados capazes ...de reduzir os sintomas da mancha angular bacteriana em casa de vegetação, os quais foram aplicados espacialmente separados do patógeno desafiador. Os melhores isolados foram testados quanto à capacidade de reduzir os sintomas da ramulose e da murcha de Verticillium e de inibir diretamente os patógenos in vitro. Do total de 123 isolados de rizobactérias foram selecionados cinco, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) e MT5-11 (Brevibacterium sp.), os quais apresentaram controle da mancha angular acima de 40%, em relação à testemunha. Nenhum isolado reduziu a severidade da ramulose e da murcha de Verticillium em relação à testemunha, nem apresentou efeito inibitório direto in vitro a X. axonopodis pv. malvacearum e Colletotrichum gossypii var. cephalosporioides. Para V. dahliae, apenas o isolado L2-1 apresentou efeito inibitório.
The potential of rhizobacteria was evaluated for resistance induction against Xanthomonas axonopodis pv. malvacearum. After isolation, the rhizobacteria were screened for the reduction of angular leaf spot severity under greenhouse conditions. They were spatially separated from the challenging pathogen. The best isolates were tested for the capacity to reduce ramulose and Verticillium wilt severity and directly inhibit pathogens in vitro. From a total of 123 rhizobacterial isolates, five were selected, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) and MT5-11 (Brevibacterium sp.), which showed angular leaf spot control above 40% as compared to the control. The tested isolates neither reduced the severity of ramulose and verticillium wilt compared to the control nor showed in vitro direct inhibition to X. axonopodis pv. malvacearum and Colletotrichum gossypii var. cephalosporioides. For V. dahliae, only isolate L2-1 showed direct inhibition.
mancha bacteriana é uma importante doença na cultura do maracujazeiro, responsável por perdas econômicas e pela redução da frutificação e do período de exploração comercial das plantas afetadas. O ...presente trabalho teve como objetivo avaliar o efeito dos produtos químicos oxitetraciclina, fluazinam, mancozeb, oxicloreto de cobre e Acibenzolar-S-Metil (ASM), das formulações Fitoforce Cobre, Fitoforce Plus e dos extratos de folhas de Artocarpus heterophyllus e Morinda citrifolia sobre o crescimento in vitro de Xanthomonas axonopodis pv. passiflorae e sobre a severidade da mancha bacteriana do maracujazeiro em casa-de-vegetação. Nos ensaios in vitro, os tratamentos foram incorporados ao meio de cultura 523, em suas respectivas dosagense as avaliações foram realizadas pela contagem do número de colônias do patógeno. Nos ensaios em casade-vegetação a aplicação dos tratamentos foi realizada 7 dias antes da inoculação de X. axonopodis pv. passiflorae para as formulações e extratos e 2 dias antes da inoculação para os produtos químicos. As avaliações de severidade da doença foram realizadas em intervalos de 48 horas. Os produtos oxitetraciclina, fluazinam, mancozeb, oxicloreto de cobre, Fitoforce Cobre e Fitoforce Plus inibiram totalmente o crescimento in vitro da bactéria. Em casa-de-vegetação, todos os tratamentos reduziram significativamente a severidade da mancha bacteriana com reduções entre 54 e 62%, com exceção do Fitoforce Plus que apresentou porcentagem de controle abaixo de 50%.
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