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Parasitism of Rhizoctonia solani by strains of Trichoderma spp. Parasitismo de Rhizoctonia solani por linhagens de Trichoderma spp.  

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Full Text Available Rhizoctonia solani causes serious diseases in a wide range of plant species. The fungus Trichoderma has been shown to be particularly effective in the control of the pathogen. Thus, this research was carried out to screen fourteen Trichoderma strains against R. solani in vitro. All strains tested inhibited the growth of R. solani. Three T. koningii strains produced toxic metabolites with strong activity against R. solani, inhibiting the mycelial growth by 79%. T. harzianum, Th-9 reduced the viability of sclerotia of R. solani by 81.8% and T. koningii, TK-5 reduced by 53%. Electron microscopic observations revealed that all T. harzianum strains interacted with R. solani. Th-9 grew toward and coiled around the host cells, penetrating and destroying the hyphae. Penetration of host cells was apparently accomplished by mechanical activity.Rhizoctonia solani é um dos mais destrutivos patógenos de plantas cultivadas. Métodos alternativos de controle têm sido empregados com sucesso, particularmente, utilizando-se o fungo Trichoderma. Este trabalho visou, portanto, selecionar linhagens efetivas desse micoparasita contra o patógeno. Onze linhagens de T. harzianum e três de T. koningii foram testadas in vitro com relação ao parasitismo de hifas e de escleródios e produção de metabólitos tóxicos. Todas as linhagens de Trichoderma spp. inibiram o crescimento miceliano de R. solani e as três linhagens de T. koningii produziram potentes antibióticos, que inibiram mais de 79% o crescimento do patógeno. Uma linhagem de T. harzianum, Th-9, reduziu a viabilidade dos escleródios em 81,8% e uma de T. koningii em 53%. Microscopia eletrônica de varredura revelou que todas as linhagens de T. harzianum parasitaram R. solani enquanto nenhuma linhagem de T. koningii interagiu com R. solani, possivelmente, devido à forte inibição causada pelos metabólitos que impediu o contato entre os dois fungos. T. harzianum, Th-9, cresceu ao redor, penetrou e destruiu as hifas de R. solani. A penetração das células hospedeiras parece ser acompanhada por atividade mecânica.

Itamar Soares de Melo

2000-03-01

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Reaction of melon genotypes to Rhizoctonia solani Reação de genótipos de melão a Rhizoctonia solani  

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The intensive exploration of melon (Cucumis melo L.) crops in the Brazilian Northeast favors the occurrence of root diseases such as the Rhizoctonia canker, caused by Rhizoctonia solani. Twenty melon genotypes were challenged against the pathogen isolates RS-9 and RS-10 aiming at selecting those potentially useful for breeding programs and/or integrated disease management. Seeds were planted in infested soil (50 mg of colonized rice grains kg-1 of soil). Disease severity was assessed 15 days ...

Michereff, Sami J.; Egt, Domingos Andrade; Rui Sales Júnior

2008-01-01

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Resistência de cultivares de arroz a Rhizoctonia solani e Rhizoctonia oryzae Resistance of rice cultivars to Rhizoctonia solani and Rhizoctonia oryzae  

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Isolados de Rhizoctonia solani e Rhizoctonia oryzae, agentes causais da queima-da-bainha e mancha-da-bainha, respectivamente, foram coletados em lavouras de arroz irrigado no Estado do Tocantins. O objetivo deste trabalho foi avaliar a resistência de 12 cultivares de arroz a essas doenças, sob condições artificiais de inoculação, em casa de vegetação. Não houve correlação entre resistência das cultivares a R. oryzae e R. solani quanto ao comprimento da lesão na bainha infectada p...

Anne Sitarama Prabhu; Marta Cristina Filippi; Gisele Barata da Silva; Gil Rodrigo de Santos

2002-01-01

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Seedling Blight of Festuca arizonica Caused by Rhizoctonia solani  

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Full Text Available We report here a damping-off disease occurring at the seedling stage of the grass Festuca arizonica (Arizona fescue that is caused by the soil-borne fungal pathogen Rhizoctonia solani.

Stanley H. Faeth

2011-03-01

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Patogenicidade de Rhizoctonia solani em morangueiro Pathogenicity of Rhizoctonia solani to strawberry  

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Full Text Available O fungo Rhizoctonia solani Kuhen tem sido isolado com maior freqüência de mudas e plantas adultas de morangueiro com sintomas de subdesenvolvimento, declínio progressivo, avermelhamento ou arroxeamento dos folíolos, pecíolos e estolhos, além do apodrecimento do ápice da coroa, estipulas e base dos pecíolos. As plantas doentes apresentavam, com freqüência, raízes escuras ou com áreas necrosadas. Fusarium spp. e Pythium spp. também estavam, reiteradamente, associados às plantas doentes. Para determinar a causa dos sintomas descritos e verificar, isoladamente ou em mistura, possível interação entre os patógenos R. solani, Fusarium sp. e Pythium sp., testaram-nos quanto à patogenicidade, em mudas de morangueiro, em casa de vegetação. Observou-se que somente quando R. solani estava presente havia reprodução dos sintomas, de modo semelhante ao observado no campo, comprovando sua patogenicidade. Fusarium e Pythium, no entanto, foram reisolados de lesões radiculares, o que indica seu possível envolvimento no complexo da doença, aumentando os sintomas de declínio em condições de campo.Rhizoctonia solani was consistently associated with strawberry plants in nurseries or in fruit production fields, with symptoms of progressive decline, stunt, reddening of leaflets, petioles and runners, besides dry rots of the crown apex, estipules and base of the petioles. These plants showed frequently roots with necrotic lesions. Fusarium spp. and Pythium spp. also were isolated from the diseased plants. This study was conducted to determine the role of each referred fungus on the disease and to investigate a possible interaction between them. For this purpose, R. solani, Pythium sp. and Fusarium sp., alone or combined one with other, were inoculated in strawberry plants, in the greenhouse. The results showed that only when R. solani was present, there was an identical reproduction of the symptoms observed in the field. Fusarium and Pythium, nevertheless, were reisolated from root lesions, indicating the possibility of its involvement with the disease, increasing the symptoms of decline under field conditions.

Maria Aparecida de Souza Tanaka

1995-01-01

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Resistência de cultivares de arroz a Rhizoctonia solani e Rhizoctonia oryzae  

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Isolados de Rhizoctonia solani e Rhizoctonia oryzae, agentes causais da queima-da-bainha e mancha-da-bainha, respectivamente, foram coletados em lavouras de arroz irrigado no Estado do Tocantins. O objetivo deste trabalho foi avaliar a resistência de 12 cultivares de arroz a essas doenças, sob condições artificiais de inoculação, em casa de vegetação. Não houve correlação entre resistência das cultivares a R. oryzae e R. solani quanto ao comprimento da lesão na bainha infectada p...

Prabhu Anne Sitarama; Filippi Marta Cristina; Silva Gisele Barata da; Santos Gil Rodrigo de

2002-01-01

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Resistência de cultivares de arroz a Rhizoctonia solani e Rhizoctonia oryzae / Resistance of rice cultivars to Rhizoctonia solani and Rhizoctonia oryzae  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Isolados de Rhizoctonia solani e Rhizoctonia oryzae, agentes causais da queima-da-bainha e mancha-da-bainha, respectivamente, foram coletados em lavouras de arroz irrigado no Estado do Tocantins. O objetivo deste trabalho foi avaliar a resistência de 12 cultivares de arroz a essas doenças, sob condi [...] ções artificiais de inoculação, em casa de vegetação. Não houve correlação entre resistência das cultivares a R. oryzae e R. solani quanto ao comprimento da lesão na bainha infectada pelo método de palito de dentes. A relação entre tamanho da lesão na bainha e folha foi linear e significativamente negativa (r = -0,66, P Abstract in english Isolates of Rhizoctonia solani and Rhizoctonia oryzae, the causal agents of sheath blight and sheath rot diseases, respectively, were collected from irrigated rice fields in the State of Tocantins, Brazil. The main objective of the investigation was to assess the resistance of 12 genotypes to these [...] diseases, under artificial inoculation tests in greenhouse condition. There was no correlation between the resistance of cultivars to R. oryzae and R. solani for lesion extension on sheath infection obtained by the toothpick method. The relationship between lesion size on sheath and leaf was linear and significantly negative (r = -0.66, P

Anne Sitarama, Prabhu; Marta Cristina, Filippi; Gisele Barata da, Silva; Gil Rodrigo de, Santos.

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Reaction of melon genotypes to Rhizoctonia solani / Reação de genótipos de melão a Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese O cultivo intensivo de melão (Cucumis melo L.) no Nordeste brasileiro tem favorecido a ocorrência de doenças radiculares como a rizoctoniose, causada pelo fungo Rhizoctonia solani. Visando selecionar genótipos com potencial de utilização nos programas de melhoramento e/ou no manejo integrado da doen [...] ça, foram avaliados 20 genótipos de melão, em relação a dois isolados do patógeno (RS-9 e RS-10). As sementes foram plantadas em solo infestado com o patógeno pela incorporação de 50 mg de substrato (grãos de arroz) colonizado kg-1 de solo. A avaliação dos genótipos foi realizada após 15 dias, com o auxílio de escala de notas de 0 a 4, para agrupamento de cada genótipo em cinco classes e cálculo do índice de severidade da doença. Nenhum dos genótipos apresentou reação de imunidade a R. solani, independentemente do isolado. Os índices de severidade da doença variaram de 6,2 a 85,4% e de 7,8 a 85,2% para os isolados RS-9 e RS-10, respectivamente. Quando considerados os dois isolados do patógeno simultaneamente, os genótipos Sancho, AF-1805, Athenas, AF-682, Torreon e Galileo comportaram-se como altamente resistentes. Os genótipos Sancho e AF-1805 apresentaram os menores índices de severidade da rizoctoniose em relação a RS-9 e, o genótipo Gold Pride, em relação a RS-10. Esses genótipos diferiram significativamente dos demais, considerando cada isolado do patógeno individualmente e, portanto, constituem fontes promissoras de resistência a R. Solani, devendo ser preferidos para plantio em áreas infestadas pelo patógeno. Abstract in english The intensive exploration of melon (Cucumis melo L.) crops in the Brazilian Northeast favors the occurrence of root diseases such as the Rhizoctonia canker, caused by Rhizoctonia solani. Twenty melon genotypes were challenged against the pathogen isolates RS-9 and RS-10 aiming at selecting those pot [...] entially useful for breeding programs and/or integrated disease management. Seeds were planted in infested soil (50 mg of colonized rice grains kg-1 of soil). Disease severity was assessed 15 days after inoculation, by means of a disease scale from 0 to 4, used later to cluster genotypes in five classes. None of the genotypes presented immune-like reaction to R. solani, independent of the pathogen isolate. Disease severity ranged from 6.2 to 85.4% and from 7.8 to 85.2%, for isolates RS-9 and RS-10, respectively. When both isolates were considered simultaneously, genotypes Sancho, AF-1805, Athenas, AF-682, Torreon, and Galileo were highly resistant. Genotypes Sancho and AF-1805 had the lowest disease severity levels in relation to isolate RS-9, and genotype Gold Pride, in relation to RS-10. These genotypes differed significantly from the others, within isolates. Therefore, they are potential sources of resistance to R. solani and should be considered as a priority planting choice in infested areas.

Sami J, Michereff; Domingos EGT, Andrade; Rui, Sales Júnior.

2008-09-01

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Reaction of melon genotypes to Rhizoctonia solani / Reação de genótipos de melão a Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O cultivo intensivo de melão (Cucumis melo L.) no Nordeste brasileiro tem favorecido a ocorrência de doenças radiculares como a rizoctoniose, causada pelo fungo Rhizoctonia solani. Visando selecionar genótipos com potencial de utilização nos programas de melhoramento e/ou no manejo integrado da doen [...] ça, foram avaliados 20 genótipos de melão, em relação a dois isolados do patógeno (RS-9 e RS-10). As sementes foram plantadas em solo infestado com o patógeno pela incorporação de 50 mg de substrato (grãos de arroz) colonizado kg-1 de solo. A avaliação dos genótipos foi realizada após 15 dias, com o auxílio de escala de notas de 0 a 4, para agrupamento de cada genótipo em cinco classes e cálculo do índice de severidade da doença. Nenhum dos genótipos apresentou reação de imunidade a R. solani, independentemente do isolado. Os índices de severidade da doença variaram de 6,2 a 85,4% e de 7,8 a 85,2% para os isolados RS-9 e RS-10, respectivamente. Quando considerados os dois isolados do patógeno simultaneamente, os genótipos Sancho, AF-1805, Athenas, AF-682, Torreon e Galileo comportaram-se como altamente resistentes. Os genótipos Sancho e AF-1805 apresentaram os menores índices de severidade da rizoctoniose em relação a RS-9 e, o genótipo Gold Pride, em relação a RS-10. Esses genótipos diferiram significativamente dos demais, considerando cada isolado do patógeno individualmente e, portanto, constituem fontes promissoras de resistência a R. Solani, devendo ser preferidos para plantio em áreas infestadas pelo patógeno. Abstract in english The intensive exploration of melon (Cucumis melo L.) crops in the Brazilian Northeast favors the occurrence of root diseases such as the Rhizoctonia canker, caused by Rhizoctonia solani. Twenty melon genotypes were challenged against the pathogen isolates RS-9 and RS-10 aiming at selecting those pot [...] entially useful for breeding programs and/or integrated disease management. Seeds were planted in infested soil (50 mg of colonized rice grains kg-1 of soil). Disease severity was assessed 15 days after inoculation, by means of a disease scale from 0 to 4, used later to cluster genotypes in five classes. None of the genotypes presented immune-like reaction to R. solani, independent of the pathogen isolate. Disease severity ranged from 6.2 to 85.4% and from 7.8 to 85.2%, for isolates RS-9 and RS-10, respectively. When both isolates were considered simultaneously, genotypes Sancho, AF-1805, Athenas, AF-682, Torreon, and Galileo were highly resistant. Genotypes Sancho and AF-1805 had the lowest disease severity levels in relation to isolate RS-9, and genotype Gold Pride, in relation to RS-10. These genotypes differed significantly from the others, within isolates. Therefore, they are potential sources of resistance to R. solani and should be considered as a priority planting choice in infested areas.

Sami J, Michereff; Domingos EGT, Andrade; Rui, Sales Júnior.

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Reaction of melon genotypes to Rhizoctonia solani Reação de genótipos de melão a Rhizoctonia solani  

Directory of Open Access Journals (Sweden)

Full Text Available The intensive exploration of melon (Cucumis melo L. crops in the Brazilian Northeast favors the occurrence of root diseases such as the Rhizoctonia canker, caused by Rhizoctonia solani. Twenty melon genotypes were challenged against the pathogen isolates RS-9 and RS-10 aiming at selecting those potentially useful for breeding programs and/or integrated disease management. Seeds were planted in infested soil (50 mg of colonized rice grains kg-1 of soil. Disease severity was assessed 15 days after inoculation, by means of a disease scale from 0 to 4, used later to cluster genotypes in five classes. None of the genotypes presented immune-like reaction to R. solani, independent of the pathogen isolate. Disease severity ranged from 6.2 to 85.4% and from 7.8 to 85.2%, for isolates RS-9 and RS-10, respectively. When both isolates were considered simultaneously, genotypes Sancho, AF-1805, Athenas, AF-682, Torreon, and Galileo were highly resistant. Genotypes Sancho and AF-1805 had the lowest disease severity levels in relation to isolate RS-9, and genotype Gold Pride, in relation to RS-10. These genotypes differed significantly from the others, within isolates. Therefore, they are potential sources of resistance to R. solani and should be considered as a priority planting choice in infested areas.O cultivo intensivo de melão (Cucumis melo L. no Nordeste brasileiro tem favorecido a ocorrência de doenças radiculares como a rizoctoniose, causada pelo fungo Rhizoctonia solani. Visando selecionar genótipos com potencial de utilização nos programas de melhoramento e/ou no manejo integrado da doença, foram avaliados 20 genótipos de melão, em relação a dois isolados do patógeno (RS-9 e RS-10. As sementes foram plantadas em solo infestado com o patógeno pela incorporação de 50 mg de substrato (grãos de arroz colonizado kg-1 de solo. A avaliação dos genótipos foi realizada após 15 dias, com o auxílio de escala de notas de 0 a 4, para agrupamento de cada genótipo em cinco classes e cálculo do índice de severidade da doença. Nenhum dos genótipos apresentou reação de imunidade a R. solani, independentemente do isolado. Os índices de severidade da doença variaram de 6,2 a 85,4% e de 7,8 a 85,2% para os isolados RS-9 e RS-10, respectivamente. Quando considerados os dois isolados do patógeno simultaneamente, os genótipos Sancho, AF-1805, Athenas, AF-682, Torreon e Galileo comportaram-se como altamente resistentes. Os genótipos Sancho e AF-1805 apresentaram os menores índices de severidade da rizoctoniose em relação a RS-9 e, o genótipo Gold Pride, em relação a RS-10. Esses genótipos diferiram significativamente dos demais, considerando cada isolado do patógeno individualmente e, portanto, constituem fontes promissoras de resistência a R. Solani, devendo ser preferidos para plantio em áreas infestadas pelo patógeno.

Sami J Michereff

2008-09-01

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Resistência de cultivares de arroz a Rhizoctonia solani e Rhizoctonia oryzae Resistance of rice cultivars to Rhizoctonia solani and Rhizoctonia oryzae  

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Full Text Available Isolados de Rhizoctonia solani e Rhizoctonia oryzae, agentes causais da queima-da-bainha e mancha-da-bainha, respectivamente, foram coletados em lavouras de arroz irrigado no Estado do Tocantins. O objetivo deste trabalho foi avaliar a resistência de 12 cultivares de arroz a essas doenças, sob condições artificiais de inoculação, em casa de vegetação. Não houve correlação entre resistência das cultivares a R. oryzae e R. solani quanto ao comprimento da lesão na bainha infectada pelo método de palito de dentes. A relação entre tamanho da lesão na bainha e folha foi linear e significativamente negativa (r = -0,66, PIsolates of Rhizoctonia solani and Rhizoctonia oryzae, the causal agents of sheath blight and sheath rot diseases, respectively, were collected from irrigated rice fields in the State of Tocantins, Brazil. The main objective of the investigation was to assess the resistance of 12 genotypes to these diseases, under artificial inoculation tests in greenhouse condition. There was no correlation between the resistance of cultivars to R. oryzae and R. solani for lesion extension on sheath infection obtained by the toothpick method. The relationship between lesion size on sheath and leaf was linear and significantly negative (r = -0.66, P<=0.05, thereby indicating that there is no relationship between resistance of sheath and leaf to infection by R. solani in rice cultivars. Among the early maturing genotypes Labelle was highly susceptible in all methods of inoculation. The area under disease progress curve based on lesion height on the culm and the inoculation method with rice husk and grain were found more adequate for determining the differences in the degree of resistance among cultivars. Leaves exhibited resistance to infection by R. oryzae in inoculation tests with mycelial discs.

Anne Sitarama Prabhu

2002-05-01

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Proteomic analysis of Rhizoctonia solani AG-1 sclerotia maturation.  

Science.gov (United States)

Rhizoctonia solani (R. solani), a soil-borne necrotrophic pathogen, causes various plant diseases. Rhizoctonia solani is a mitosporic fungus, the sclerotium of which is the primary inoculum and ensures survival of the fungus during the offseason of the host crop. Since the fungus does not produce any asexual or sexual spores, understanding the biology of sclerotia is important to examine pathogen ecology and develop more efficient methods for crop protection. Here, one- and two-dimensional gel electrophoresis (1-DE and 2-DE, respectively) were used to examine protein regulation during the maturation of fungal sclerotia. A total of 75 proteins (20 proteins from 1-DE using matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF) mass spectrometry (MS) and 55 proteins from 2-DE using MALDI-TOF MS or MALDI-TOF/TOF MS) were differentially expressed during sclerotial maturation. The identified proteins were classified into ten categories based on their biological functions, including genetic information processing, carbohydrate metabolism, cell defense, amino acid metabolism, nucleotide metabolism, cellular processes, pathogenicity and mycotoxin production, and hypothetical or unknown functions. Interestingly, two vacuole function-related proteins were highly up-regulated throughout sclerotial maturation, which was confirmed at the transcript level by reverse transcriptase polymerase chain reaction (RT-PCR) analysis. These findings contribute to our understanding of the biology of R. solani sclerotia. PMID:24863472

Kwon, Young Sang; Kim, Sang Gon; Chung, Woo Sik; Bae, Hanhong; Jeong, Sung Woo; Shin, Sung Chul; Jeong, Mi-Jeong; Park, Soo-Chul; Kwak, Youn-Sig; Bae, Dong-Won; Lee, Yong Bok

2014-01-01

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Optimized protein extraction methods for proteomic analysis of Rhizoctonia solani.  

Science.gov (United States)

Rhizoctonia solani (Teleomorph: Thanatephorus cucumeris, T. praticola) is a basidiomycetous fungus and a major cause of root diseases of economically important plants. Various isolates of this fungus are also beneficially associated with orchids, may serve as biocontrol agents or remain as saprophytes with roles in decaying and recycling of soil organic matter. R. solani displays several hyphal anastomosis groups (AG) with distinct host and pathogenic specializations. Even though there are reports on the physiological and histological basis of Rhizoctonia-host interactions, very little is known about the molecular biology and control of gene expression early during infection by this pathogen. Proteamic technologies are powerful tools for examining alterations in protein profiles. To aid studies on its biology and host pathogen interactions, a two-dimensional (2-D) gel-based global proteomic study has been initiated. To develop an optimized protein extraction protocol for R. solani, we compared two previously reported protein extraction protocols for 2-D gel analysis of R. solani (AG-4) isolate Rs23. Both TCA-acetone precipitation and phosphate solubilization before TCA-acetone precipitation worked well for R. solani protein extraction, although selective enrichment of some proteins was noted with either method. About 450 spots could be detected with the densitiometric tracing of Coomassie blue-stained 2-D PAGE gels covering pH 4-7 and 6.5-205 kDa. Selected protein spots were subjected to mass spectrometric analysis with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Eleven protein spots were positively identified based on peptide mass fingerprinting match with fungal proteins in public databases with the Mascot search engine. These results testify to the suitability of the two optimized protein extraction protocols for 2-D proteomic studies of R. solani. PMID:19202841

Lakshman, Dilip K; Natarajan, Savithiry S; Lakshman, Sukla; Garrett, Wesley M; Dhar, Arun K

2008-01-01

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A quitosana como fungistático no crescimento micelial de Rhizoctonia solani Kuhn / Chitosan as fungistatic mycelial growth of Rhizoctonia solani Kuhn  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Rhizoctonia solani é um fungo causador de tombamento de plântulas em várias espécies vegetais. A quitosana é um polímero derivado do processo de desacetilação da quitina, a qual é encontrada em grande quantidade na carapaça de crustáceos, insetos e parede celular de fungos. A quitosana tem sido test [...] ada para diversos usos, inclusive no controle de fitopatógenos em agricultura, já que apresenta atividade antimicrobiana, para controle de patógenos. O presente trabalho teve como objetivo avaliar o efeito fungistático de diferentes concentrações de quitosana (0; 0,25; 0,5; 1 e 2%) no crescimento micelial do fungo R. solani in vitro. Os resultados obtidos demonstraram efeito significativo de quitosana nas diferentes concentrações utilizadas, na redução do crescimento micelial de R. solani. Observou-se também aumento do efeito fungistático da quitosana conforme o aumento da dose. Abstract in english Rhizoctonia solani is a fungus that causes damping-off of seedlings in various plant species. Chitosan is a polymer derived from the process of desacetylation of chitin, which is found in large quantities in the exoskeleton of crustaceans, insects and fungal cell wall. Chitosan has been tested for v [...] arious uses, including the control of plant pathogens in agriculture, since it presents antimicrobial activity to control pathogens. This study aimed to evaluate the fungistatic effect of different chitosan concentrations (0; 0.25; 0.5; 1 and 2%) in mycelial growth in vitro of the fungus R. solani. The results showed a significant effect of different concentrations of chitosan, in reduccing the mycelial growth of R. solani. It was also observed increased fungistatic effect with increasing of the concentration.

Álvaro Rodrigo, Freddo; Sérgio Miguel, Mazaro; Eleandro José, Brun; Américo, Wagner Júnior.

2014-01-01

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Pea seed treatment for Rhizoctonia solani control / Desempenho de sementes de ervilhas em função do controle químico de Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Durante o estabelecimento das lavouras de ervilha, a ocorrência de Rhizoctonia solani causando tombamento de plântulas tem sido observada. O presente trabalho teve como objetivo verificar a eficiência do uso de fungicidas no tratamento de sementes de ervilha cultivar Mikado, visando o controle de Rh [...] izoctonia solani e seus efeitos na qualidade fisiológica dessas sementes. Sementes foram tratadas com os seguintes fungicidas: Carbendazim, Carbendazim + Thiram, Captan, Iprodione, Iprodione + Thiram, Metalaxil-M + Fludioxonil, Pencicurom, Procimidone e Tolifluanida. Como testemunha, foi utilizada sementes tratadas com água destilada. A avaliação da qualidade fisiológica das sementes após o tratamento foi realizada pelos seguintes testes: germinação, primeira contagem, envelhecimento acelerado, condutividade elétrica e emergência de plântulas. As sementes tratadas foram semeadas em solo não inoculado e inoculado com R. solani. A emergência de plântulas foi reduzida em solo inoculado, sendo que os tratamentos que apresentaram melhores resultados foram Carbendazim, Pencicurom, Iprodione e Carbendazim + Thiram. O fungicida Captan prejudicou a qualidade fisiológica das sementes tanto em laboratório como no campo. Com relação à germinação, os tratamentos que apresentaram melhores resultados foram Carbendazim, Pencicurom, Iprodione e Carbendazim + Thiram. Abstract in english The objectives of this study were to evaluate the efficiency of fungicides for pea seed treatment against damping-off caused by Rhizoctonia solani and to verify their effects on physiological seed quality. 'Mikado' pea seeds were treated with the following fungicides: Carbendazim, Carbendazim + Thir [...] am, Captan, Iprodione, Iprodione + Thiram, Metalaxyl-M + Fludioxonil, Pencycuron, Procymidone and Tolyfluanid. Control seeds were treated with deionized water. Physiological seed quality was evaluated with the following tests: germination, first count, accelerated aging and electrical conductivity. Seeds were sown in soil inoculated and no inoculated with R. solani. The experimental design was completely random with four replications. Seedling emergence was reduced in inoculated soil and the best treatments for R. solani control were Carbendazim, Pencycuron, Iprodione and Carbendazim + Thiram. Captan reduced seed physiological quality in both the laboratory and field.

Patrícia Pereira da, Silva; Raquel Alves de, Freitas; Warley Marcos, Nascimento.

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A quitosana como fungistático no crescimento micelial de Rhizoctonia solani Kuhn / Chitosan as fungistatic mycelial growth of Rhizoctonia solani Kuhn  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Rhizoctonia solani é um fungo causador de tombamento de plântulas em várias espécies vegetais. A quitosana é um polímero derivado do processo de desacetilação da quitina, a qual é encontrada em grande quantidade na carapaça de crustáceos, insetos e parede celular de fungos. A quitosana tem sido test [...] ada para diversos usos, inclusive no controle de fitopatógenos em agricultura, já que apresenta atividade antimicrobiana, para controle de patógenos. O presente trabalho teve como objetivo avaliar o efeito fungistático de diferentes concentrações de quitosana (0; 0,25; 0,5; 1 e 2%) no crescimento micelial do fungo R. solani in vitro. Os resultados obtidos demonstraram efeito significativo de quitosana nas diferentes concentrações utilizadas, na redução do crescimento micelial de R. solani. Observou-se também aumento do efeito fungistático da quitosana conforme o aumento da dose. Abstract in english Rhizoctonia solani is a fungus that causes damping-off of seedlings in various plant species. Chitosan is a polymer derived from the process of desacetylation of chitin, which is found in large quantities in the exoskeleton of crustaceans, insects and fungal cell wall. Chitosan has been tested for v [...] arious uses, including the control of plant pathogens in agriculture, since it presents antimicrobial activity to control pathogens. This study aimed to evaluate the fungistatic effect of different chitosan concentrations (0; 0.25; 0.5; 1 and 2%) in mycelial growth in vitro of the fungus R. solani. The results showed a significant effect of different concentrations of chitosan, in reduccing the mycelial growth of R. solani. It was also observed increased fungistatic effect with increasing of the concentration.

Álvaro Rodrigo, Freddo; Sérgio Miguel, Mazaro; Eleandro José, Brun; Américo, Wagner Júnior.

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Incompatibilidade somática em Rhizoctonia solani AG-1 IA da soja Somatic incompatibility in Rhizoctonia solani AG-1 IA of soybean  

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Full Text Available O fungo Rhizoctonia solani AG-1 IA é um dos patógenos mais importantes que afeta a cultura da soja no Brasil, causando a mela ou queima foliar. A doença está associada com a fase teleomórfica de R. solani, o basidiomiceto Thanatephorus cucumeris. Neste estudo, baseando em conhecimento prévio sobre a biologia de R. solani AG-1 IA, duas hipóteses foram testadas. Na primeira hipótese postulou-se a ocorrência de incompatibilidade somática em populações de R. solani AG-1 IA. A segunda hipótese testada foi de que esta população de R. solani AG-1 IA da soja apresenta indicações de estrutura sexual clonal. Duas amostras de isolados de R. solani AG-1 IA da soja obtidas no Maranhão e no Mato Grosso foram utilizadas. Na primeira amostra, foram selecionados isolados apresentando diferentes perfis de RAPD (Random Amplified Polymorphic DNA, procurando maximizar a diversidade dos isolados, e evitando a introdução de possíveis clones no teste. Os isolados foram pareados em todas as combinações possíveis em meio de BDA mais carvão ativado e examinados quanto às interações somáticas resultantes. Seis grupos de incompatibilidade somática (GCS foram detectados entre 24 isolados do AG-1 IA. Entretanto, análises microscópicas dos pareamentos entre isolados indicaram maior freqüência de incompatibilidade somática, impossibilitando o grupamento em GCS. No geral, a metodologia de avaliação das interações somáticas macroscópicas em meio BDA + carvão ativado, não se mostrou totalmente apropriada para discriminação das categorias de reações de compatibilidade entre isolados de R. solani AG-1 IA. Com a segunda amostra procurou-se determinar a ocorrência de clones na população do patógeno, ou seja, isolados que compartilham o mesmo padrão fenotípico de RAPD e somaticamente compatíveis. No caso de R. solani AG 1 IA da soja, a gama de interações somáticas entre pareamentos de isolados e, principalmente, os desvios na associação estrita entre os GCS detectados neste trabalho, conjuntamente com os perfis de RAPD observados anteriormente por Fenille (11 e Meyer (20, são consistentes com recombinação. Entretanto, o patógeno ainda apresenta um componente clonal expressivo na população. De um total de 43 isolados, os exemplos de prováveis clones na população do patógeno totalizaram 16 isolados.Rhizoctonia solani anastomosis group 1 IA (AG-1 IA is considered one of the most important pathogens affecting soybean in Brazil, causing the aerial or foliar blight. This disease is associated with the teleomorphase of R. solani AG-1 IA, the basidiomycete fungus Thanatephorus cucumeris. In this study, based on previous knowledge of the biology of R. solani AG-1 IA, two hypotheses were tested. In the first we postulated the occurrence of somatic incompatibility in populations of R. solani AG-1 IA. The second was that the population of R. solani AG1 IA from soybean has a clonal structure. Two population samples of R. solani AG-1 IA from soybean, obtained in Maranhão and Mato Grosso were analyzed. In the first sample, isolates with distinct RAPD (Random Amplified Polymorphic DNA profile were selected to maximize the genetic diversity of isolates and to avoid the introduction of clones in the assay. The isolates were paired in all possible combinations in PDA plus charcoal medium and examined according to the resulting somatic interactions. Six somatic compatibility groups (SCG were detected among 24 isolates of AG-1 IA. However, microscopic analyzes of the pairings indicated higher frequency of somatic incompatibility, resulting in the impossibility of grouping any two isolates of R. solani AG-1 IA into SCG. In general, the methodology for evaluating the macroscopic somatic interactions in PDA plus charcoal medium seemed not totally appropriate for discriminating between categories of somatic compatibility amongst isolates of R. solani AG-1 IA. With the second sample of isolates we aimed to determine the occurrence of clones in the population of the pathogen, i.e., isolates that sha

Ana Paula da Silva de Campos

2006-09-01

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Incompatibilidade somática em Rhizoctonia solani AG-1 IA da soja / Somatic incompatibility in Rhizoctonia solani AG-1 IA of soybean  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O fungo Rhizoctonia solani AG-1 IA é um dos patógenos mais importantes que afeta a cultura da soja no Brasil, causando a mela ou queima foliar. A doença está associada com a fase teleomórfica de R. solani, o basidiomiceto Thanatephorus cucumeris. Neste estudo, baseando em conhecimento prévio sobre a [...] biologia de R. solani AG-1 IA, duas hipóteses foram testadas. Na primeira hipótese postulou-se a ocorrência de incompatibilidade somática em populações de R. solani AG-1 IA. A segunda hipótese testada foi de que esta população de R. solani AG-1 IA da soja apresenta indicações de estrutura sexual clonal. Duas amostras de isolados de R. solani AG-1 IA da soja obtidas no Maranhão e no Mato Grosso foram utilizadas. Na primeira amostra, foram selecionados isolados apresentando diferentes perfis de RAPD (Random Amplified Polymorphic DNA), procurando maximizar a diversidade dos isolados, e evitando a introdução de possíveis clones no teste. Os isolados foram pareados em todas as combinações possíveis em meio de BDA mais carvão ativado e examinados quanto às interações somáticas resultantes. Seis grupos de incompatibilidade somática (GCS) foram detectados entre 24 isolados do AG-1 IA. Entretanto, análises microscópicas dos pareamentos entre isolados indicaram maior freqüência de incompatibilidade somática, impossibilitando o grupamento em GCS. No geral, a metodologia de avaliação das interações somáticas macroscópicas em meio BDA + carvão ativado, não se mostrou totalmente apropriada para discriminação das categorias de reações de compatibilidade entre isolados de R. solani AG-1 IA. Com a segunda amostra procurou-se determinar a ocorrência de clones na população do patógeno, ou seja, isolados que compartilham o mesmo padrão fenotípico de RAPD e somaticamente compatíveis. No caso de R. solani AG 1 IA da soja, a gama de interações somáticas entre pareamentos de isolados e, principalmente, os desvios na associação estrita entre os GCS detectados neste trabalho, conjuntamente com os perfis de RAPD observados anteriormente por Fenille (11) e Meyer (20), são consistentes com recombinação. Entretanto, o patógeno ainda apresenta um componente clonal expressivo na população. De um total de 43 isolados, os exemplos de prováveis clones na população do patógeno totalizaram 16 isolados. Abstract in english Rhizoctonia solani anastomosis group 1 IA (AG-1 IA) is considered one of the most important pathogens affecting soybean in Brazil, causing the aerial or foliar blight. This disease is associated with the teleomorphase of R. solani AG-1 IA, the basidiomycete fungus Thanatephorus cucumeris. In this st [...] udy, based on previous knowledge of the biology of R. solani AG-1 IA, two hypotheses were tested. In the first we postulated the occurrence of somatic incompatibility in populations of R. solani AG-1 IA. The second was that the population of R. solani AG1 IA from soybean has a clonal structure. Two population samples of R. solani AG-1 IA from soybean, obtained in Maranhão and Mato Grosso were analyzed. In the first sample, isolates with distinct RAPD (Random Amplified Polymorphic DNA) profile were selected to maximize the genetic diversity of isolates and to avoid the introduction of clones in the assay. The isolates were paired in all possible combinations in PDA plus charcoal medium and examined according to the resulting somatic interactions. Six somatic compatibility groups (SCG) were detected among 24 isolates of AG-1 IA. However, microscopic analyzes of the pairings indicated higher frequency of somatic incompatibility, resulting in the impossibility of grouping any two isolates of R. solani AG-1 IA into SCG. In general, the methodology for evaluating the macroscopic somatic interactions in PDA plus charcoal medium seemed not totally appropriate for discriminating between categories of somatic compatibility amongst isolates of R. solani AG-1 IA. With the second sample of isolates we a

Ana Paula da Silva de, Campos; Paulo Cezar, Ceresini.

2006-09-01

19

Incompatibilidade somática em Rhizoctonia solani AG-1 IA da soja / Somatic incompatibility in Rhizoctonia solani AG-1 IA of soybean  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O fungo Rhizoctonia solani AG-1 IA é um dos patógenos mais importantes que afeta a cultura da soja no Brasil, causando a mela ou queima foliar. A doença está associada com a fase teleomórfica de R. solani, o basidiomiceto Thanatephorus cucumeris. Neste estudo, baseando em conhecimento prévio sobre a [...] biologia de R. solani AG-1 IA, duas hipóteses foram testadas. Na primeira hipótese postulou-se a ocorrência de incompatibilidade somática em populações de R. solani AG-1 IA. A segunda hipótese testada foi de que esta população de R. solani AG-1 IA da soja apresenta indicações de estrutura sexual clonal. Duas amostras de isolados de R. solani AG-1 IA da soja obtidas no Maranhão e no Mato Grosso foram utilizadas. Na primeira amostra, foram selecionados isolados apresentando diferentes perfis de RAPD (Random Amplified Polymorphic DNA), procurando maximizar a diversidade dos isolados, e evitando a introdução de possíveis clones no teste. Os isolados foram pareados em todas as combinações possíveis em meio de BDA mais carvão ativado e examinados quanto às interações somáticas resultantes. Seis grupos de incompatibilidade somática (GCS) foram detectados entre 24 isolados do AG-1 IA. Entretanto, análises microscópicas dos pareamentos entre isolados indicaram maior freqüência de incompatibilidade somática, impossibilitando o grupamento em GCS. No geral, a metodologia de avaliação das interações somáticas macroscópicas em meio BDA + carvão ativado, não se mostrou totalmente apropriada para discriminação das categorias de reações de compatibilidade entre isolados de R. solani AG-1 IA. Com a segunda amostra procurou-se determinar a ocorrência de clones na população do patógeno, ou seja, isolados que compartilham o mesmo padrão fenotípico de RAPD e somaticamente compatíveis. No caso de R. solani AG 1 IA da soja, a gama de interações somáticas entre pareamentos de isolados e, principalmente, os desvios na associação estrita entre os GCS detectados neste trabalho, conjuntamente com os perfis de RAPD observados anteriormente por Fenille (11) e Meyer (20), são consistentes com recombinação. Entretanto, o patógeno ainda apresenta um componente clonal expressivo na população. De um total de 43 isolados, os exemplos de prováveis clones na população do patógeno totalizaram 16 isolados. Abstract in english Rhizoctonia solani anastomosis group 1 IA (AG-1 IA) is considered one of the most important pathogens affecting soybean in Brazil, causing the aerial or foliar blight. This disease is associated with the teleomorphase of R. solani AG-1 IA, the basidiomycete fungus Thanatephorus cucumeris. In this st [...] udy, based on previous knowledge of the biology of R. solani AG-1 IA, two hypotheses were tested. In the first we postulated the occurrence of somatic incompatibility in populations of R. solani AG-1 IA. The second was that the population of R. solani AG1 IA from soybean has a clonal structure. Two population samples of R. solani AG-1 IA from soybean, obtained in Maranhão and Mato Grosso were analyzed. In the first sample, isolates with distinct RAPD (Random Amplified Polymorphic DNA) profile were selected to maximize the genetic diversity of isolates and to avoid the introduction of clones in the assay. The isolates were paired in all possible combinations in PDA plus charcoal medium and examined according to the resulting somatic interactions. Six somatic compatibility groups (SCG) were detected among 24 isolates of AG-1 IA. However, microscopic analyzes of the pairings indicated higher frequency of somatic incompatibility, resulting in the impossibility of grouping any two isolates of R. solani AG-1 IA into SCG. In general, the methodology for evaluating the macroscopic somatic interactions in PDA plus charcoal medium seemed not totally appropriate for discriminating between categories of somatic compatibility amongst isolates of R. solani AG-1 IA. With the second sample of isolates we a

Ana Paula da Silva de, Campos; Paulo Cezar, Ceresini.

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Antagonism of some soil microflora species against pathogenic Fusarium graminearum Schwabe and Rhizoctonia solani Kuhn agents  

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Full Text Available In vitro results of some soil micoflora species antagonisms against pathogenic Fussarium graminearum Schwabe and Rhizoctonia solani Kuhn agents are presented. Following tets performed Aspergillus spp., Trichoderma viride and Penicillium spp. Were found to be antagonist against Fusarium graminearum. Antagonist against Rhizoctonia solani were found to be Trichoderma viride, Aspergillus spp., Penicillium spp. and Trichothecium roseum.

N. FLOREA

1973-08-01

 
 
 
 
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Some Properties of Inulinase from Rhizoctonia solani  

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Full Text Available The preparation and some biochemical properties of inulinase from R. solani which isolated from soil in Tekirdag - Turkey, was carried out by dialysis and concentrated with silica gel-60 then, further proceeded with Sephadex G-150 and DEAE-Cellulose chromatographies. The specific activity of the enzyme was enhanced from 0.256-5.43 U mg -1. The enzyme showed maximum activity at 35?C and pH 5.0, it was stable in the pH range of 5.0-6.5 and up to 40?C. The activity of enzyme was inhibited strongly by Hg2+ and Ag2+ and KCN and DTNB. The action mode of enzyme for inulin was determined as endohydrolitic-action by TLC.

Figen Ertan

2005-01-01

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CHEMICAL CONTROL OF Rhizoctonia solani Kuhn IN SEED POTATO CONTROLE QUÍMICO DE Rhizoctonia solani Kuhn EM BATATA SEMENTE  

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Full Text Available

The fungicides benomyl (200 g.a.i./100 kg seeds, iprodione (200 g.a.i./l00kg seeds and pencycuron (62.5 g.a.i./100 kg seeds were evaluated, under greenhouse conditions on controlling Rhizoctonia solani Kuhn, in seed potato, with variety Desirée. The evaluation of the germination percentage and damping-off, at 25 days of age, showed that the best treatment was presented through the use of penycuron, but this fungicide had no significant difference in relation to iprodione treatment.

Os fungicidas benomyl (200 g.i.a./100 kg sementes, iprodione (200 g.i.a./100 kg sementes e pencycuron (62,5 g.i.a./100 kg de sementes foram testados, em condições de telado, no controle de Rhizoctonia solani Kuhn., em batata semente da cultivar Desirée. A avaliação da percentagem de emergência damping-off aos 25 dias após o plantio, demonstrou que os fungicidas pencycuron e iprodione foram os melhores, com vantagens para o primeiro, porém sem diferirem entre si significativamente.

Cláudio Aparecido da Silveira

2007-09-01

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TEMPERATURE EFFECT ON RHIZOCTONIA SOLANI ANALYZED BY MICROCALORIMETRY  

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Full Text Available Temperature is one of the factors playing an important role in fungi growth and spread. The aim of this study was to determine the effect of temperature on the growth of ten Rhizoctonia solani isolates. Colony Growth Rate (GR was measured in potato-agar-dextrose cultures and Metabolic Efficiency (ME by isothermal microcalorimetry in R. solani isolates growing in a temperature range of 10 to 40°C at 5°C intervals. The apparent activation Energy (Ea was determined in the range of 15 to 30°C. Different values of Ea were found for each of the strains analyzed. GR increased as temperature increased up to 30°C, showing the highest values between 25°C. ME decreased as temperature increased in nine out of ten isolates, reaching an optimum for the different isolates between 15 and 25°C. Both GR and ME analyses showed different behaviors for each isolate. R. solani AG4 isolates showed a variable response to the same temperature of exposure and it appears that microcalorimetry is more sensitive in detecting early effects of heat stress.

Antonio Orozco-Avitia

2013-01-01

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REAÇÃO DE CULTIVARES DO FEIJOEIRO COMUM ÀS PODRIDÕES RADICULARES CAUSADAS POR Rhizoctonia solani E Fusarium solani f. sp. phaseoli  

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Full Text Available REACTION OF COMMON BEAN CULTIVARS TOROOT ROT CAUSED BY Rhizoctonia solaniAND Fusarium solani f. sp. phaseoliRhizoctonia solani Kuhn is a necrotrophic fungus andsoil inhabitant that attacks great number of vegetable species. Inbean plants, R. solani can induce different symptoms includingtoppling, root and colon plant rottenness. Fusarium solani (MartSacc. f. sp. phaseoli (Burcholder occurs in practically all beanproducing areas in Brazil and can cause root rots and death tobean plants. This study evaluated the reaction of commercialcommon bean cultivars growing in R. solani or F. solani f. sp.phaseoli infested soil, under green house conditions. Theexperimental design was entirely randomized, with 24 treatmentsand four replications. A Oxisol was infested with trituratedsorghum grains that were previously colonized by R. solani (1.0g/1.4 L of soil or F. solani f. sp phaseoli (8.0 g/1.4 L of soil. Thedisease evaluations were accomplished 21 days after planting.All plants were carefully removed, their root systems werewashed in running water and the disease severity was evaluatedaccording to Abawi & Pastor-Corrales (1990 scale for diseaseseverity. The cultivar behavior ranged according to the inoculatedpathogen, all cultivars were susceptible with different degrees ofsusceptibility. Among evaluated common bean cultivars Pérolawas less susceptible to R. solani, and Radiante was lesssusceptible to F. solani f. sp. phaseoli.

Braycia Afonso de Miranda

2007-12-01

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Studies on Biological Control of Sugarbeet Pathogen Rhizoctonia solani Kuhn  

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Full Text Available A field experiment was carried out to investigate the biological control of R. solani by different organisms including bacteria and fungi. Three methods of application were used during the study. Control results differed with the method of application used. The present study indicated that all the antagonists tested inhibited infection by R. solani and that the efficacy of prevention depended on the application method used. Coating sugarbeet seeds with antagonists was produced results for applying the antagonist to control R. solani. A soil preinoculation that contained the antagonist was better than treating them with extracts of antagonists although antimicrobial compounds in the extracts have been found to control the disease to the same extent. The most effective biocontrol agent was Trichoderma harzianum. Hyphal interactions between T. harzianum and R. solani were observed by scanning electron microscopy. T. harzianum attached to the host by hyphal coils.

Tarek A.A. Moussa

2002-01-01

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Metodologias de inoculação de Rhizoctonia solani na cultura da cenoura / Inoculation methodology of Rhizoctonia solani in carrot  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Rhizoctonia solani pode causar diferentes tipos de doenças em cenoura (Daucus carota L.). Para a avaliação de métodos de controle geralmente se utiliza inoculação artificial. Objetivou-se neste trabalho, ajustar uma concentração de inóculo de R. solani (AG-4) no cultivo de cenoura. Utilizou-se delin [...] eamento experimental em blocos ao acaso, com 5 repetições sendo a unidade experimental um vaso de 3L com 40 sementes. Como substrato, utilizou-se solo/areia (3:1). Os tratamentos em esquema fatorial 4 x 3 sendo, 4 densidades de inóculo (9; 18; 36; 72; mg de inóculo·kg-1 de solo) e 3 métodos de infestação artificial (incorporados a todo o solo; incorporados na superfície; contato direto com as sementes) e uma testemunha adicional. O experimento foi conduzido em câmara de crescimento a 20(0)C, com fotoperíodo de 12 h. As avaliações foram realizadas diariamente do 8º ao 30º dia após a semeadura, registrando-se o estande e o número de plântulas com tombamento. Analisou-se o índice de velocidade de emergência, porcentagem média de tombamento pré e pós emergência. A densidade de 72 mg de inóculo·kg-1 de solo incorporado na superfície foi o método mais eficiente. Abstract in english Rhizoctonia solani may cause different diseases in carrot (Daucus carota L.). To test control methods, artificial inoculation is generally employed. This work aimed to adjust a methodology to inoculate R. solani (AG-4) in carrot. A randomized block outline with five replicates was used, with an expe [...] rimental unit of a 3L-pot with 40 seeds and a substact composed by a mixture of soil/sand (3:1 v/v). Treatments were those in a factorial experiment 4 x 3, with 4 inoculum densities (9; 18; 36; 72 mg of inoculum.kg-1 of soil) and three forms of artificial infestation (incorporated to the substract as a whole; incorporated on the surface; with direct contact with seeds) and an additional control. The experiment was carried out in a growth chamber at 20(0)C and a 12h photoperiod. The evaluations were daily performed from the 8th to the 30th day after sowing, recording plant stand and number of seedlings with damping-off. The emergence index, averge percentage of pre and post emergence. Were analyzed the density of 72 mg of inoculum·kg-1 of soil, incorporated on the surface of the susbtract was the most efficient inoculation method.

Amanda Cabral Corrêa de, Oliveira; Paulo Estevão de, Souza; Edson Ampélio, Pozza; Felipe de Carvalho, Manerba; Maurício Ferreira, Lopes.

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Relação entre coberturas vegetais e supressividade de solos a Rhizoctonia solani Relationship between vegetation and soil suppressiveness to Rhizoctonia solani  

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Full Text Available Áreas de uma microbacia sem a incidência de doenças causadas por Rhizoctonia solani GA 4 foram agrupadas estatisticamente, pelo método de Ward, com relação à supressividade dos solos ao patógeno, avaliada pela taxa de crescimento micelial. Entre os grupos formados, foi definido um gradiente de supressividade. A relação entre gradientes de supressividade e tipos de cobertura vegetal foi descrita com auxílio da análise de correspondências múltiplas, sendo que, de modo geral, o pasto e o pousio, seguidos da mata, tornaram os solos mais supressivos, ao passo que a cana-de-açúcar (Saccharum officinarum, o milho (Zea mays , o café (Coffea arabica e o solo arado tornaram os solos mais conducentes. Porém, os resultados mostraram que outros fatores, além da cobertura vegetal, podem estar afetando a supressividade. Um tratamento biocida (fumigação dos solos mais supressivos promoveu um maior incremento da taxa de crescimento do patógeno do que o observado com solos mais conducentes.Areas from a microbasin without the incidence of plant diseases caused by Rhizoctonia solani GA 4 were statistically grouped by Ward's method, in relation to soil suppressiveness, described by the mycelial growth rate. A gradient of suppressiveness was defined between the groups. The relationship between suppressiveness and types of vegetation was described by a multiple correspondence analysis. In general, soils from pasture, fallow ground and forest were classified as suppressive soils, while sugar cane (Saccharum officinarum, maize (Zea mays , coffee (Coffea arabica and ploughed soils, as conducive soils. However, results showed that other factors affect suppressiveness besides vegetation. A biocide treatment (fumigation promoted a greater increase in the growth rate of the pathogen on suppressive soils than on conducive ones

RAQUEL GHINI

2001-03-01

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Susceptibility of leguminous green manure species to Rhizoctonia solani and Sclerotium rolfsii / Suscetibilidade de espécies de leguminosas usadas como adubo verde a Rhizoctonia solani e Sclerotium rolfsii  

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese Estudou-se a suscetibilidade de leguminosas utilizadas como adubos verdes em campos cultivados com feijão à podridão-radicular (Rhizoctonia solani) e à podridão-do-colo (Sclerotium rolfsii). Crotalaria breviflora, Canavalia ensiformis, Cajanus cajan, Dolichos lablab, Stizolobium cinereum, S. aterrim [...] um, e as cultivares de feijão Pérola, Valente e Carnaval foram semeadas em solo infestado por R. solani AG-4 ou S. rolfsii em casa de vegetação. A emergência de D. lablab em solo infestado por R. solani foi reduzida a 62%. C. breviflora, C. ensiformis e Valente apresentaram a menor severidade de podridão-radicular. O fungo S. rolfsii reduziu drasticamente a emergência de todas as espécies; nenhuma plântula de C. cajan e S. cinereum emergiu. Todas as espécies apresentaram alta severidade de podridão-do-colo. As espécies de leguminosas testadas não são apropriadas para serem utilizadas como adubo verde em áreas de cultivo de feijão com alta população de R. solani e S. rolfsii. Abstract in english We studied the susceptibility of species used as green manure in common bean fields to root rot (Rhizoctonia solani) and southern blight (Sclerotium rolfsii). Seeds of Crotalaria breviflora, Canavalia ensiformis, Cajanus cajan, Dolichos lablab, Stizolobium cinereum, S. aterrimum, and the bean cvs. " [...] Pérola", "Valente" and "Carnaval" were sown in soil infested by either R. solani AG-4 or S. rolfsii in greenhouse. The emergence of D. lablab seedlings in soil infested by R. solani dropped to 62%. C. breviflora, C. ensiformis and cv. "Valente" presented the lowest root rot severity. The pathogen S. rolfsii drastically reduced seedling emergence in all species; no C. cajan and S. cinereum seedling emerged. All plant species presented high southern blight severity. We conclude that leguminous crops are not suitable as green manure for areas of bean cultivation with high R. solani and S. rolfsii populations.

Trazilbo José de, Paula Júnior; Hudson, Teixeira; Rogério Faria, Vieira; Miller da Silva, Lehner; Renan Cardoso de, Lima; Telma Fallieri Nascimento, Queiroz.

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Susceptibility of leguminous green manure species to Rhizoctonia solani and Sclerotium rolfsii Suscetibilidade de espécies de leguminosas usadas como adubo verde a Rhizoctonia solani e Sclerotium rolfsii  

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Full Text Available We studied the susceptibility of species used as green manure in common bean fields to root rot (Rhizoctonia solani and southern blight (Sclerotium rolfsii. Seeds of Crotalaria breviflora, Canavalia ensiformis, Cajanus cajan, Dolichos lablab, Stizolobium cinereum, S. aterrimum, and the bean cvs. "Pérola", "Valente" and "Carnaval" were sown in soil infested by either R. solani AG-4 or S. rolfsii in greenhouse. The emergence of D. lablab seedlings in soil infested by R. solani dropped to 62%. C. breviflora, C. ensiformis and cv. "Valente" presented the lowest root rot severity. The pathogen S. rolfsii drastically reduced seedling emergence in all species; no C. cajan and S. cinereum seedling emerged. All plant species presented high southern blight severity. We conclude that leguminous crops are not suitable as green manure for areas of bean cultivation with high R. solani and S. rolfsii populations.Estudou-se a suscetibilidade de leguminosas utilizadas como adubos verdes em campos cultivados com feijão à podridão-radicular (Rhizoctonia solani e à podridão-do-colo (Sclerotium rolfsii. Crotalaria breviflora, Canavalia ensiformis, Cajanus cajan, Dolichos lablab, Stizolobium cinereum, S. aterrimum, e as cultivares de feijão Pérola, Valente e Carnaval foram semeadas em solo infestado por R. solani AG-4 ou S. rolfsii em casa de vegetação. A emergência de D. lablab em solo infestado por R. solani foi reduzida a 62%. C. breviflora, C. ensiformis e Valente apresentaram a menor severidade de podridão-radicular. O fungo S. rolfsii reduziu drasticamente a emergência de todas as espécies; nenhuma plântula de C. cajan e S. cinereum emergiu. Todas as espécies apresentaram alta severidade de podridão-do-colo. As espécies de leguminosas testadas não são apropriadas para serem utilizadas como adubo verde em áreas de cultivo de feijão com alta população de R. solani e S. rolfsii.

Trazilbo José de Paula Júnior

2011-12-01

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Application of Fluorescent Pseudomonads in Biological Control of Rhizoctonia solani , Causal Agent of Colza  

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  Two hundred fifty seven bacterial isolates were collected from colza root and rhizosphere in Golestan, Mazandaran, Guilan and Tehran provinces. Antagonistic effect of bacterial isolates on Rhizoctonia solani, the causal agent of colza damping off, was studied using dual culture method. The results showed that, 60 isolates had the ability to inhibit the growth of R. solani on PDA medium. On the basis of the biochemical, physiological and morphological tests, isolates P1, P2 and P3 were iden...

Javan Nikkhah, M.; Ahmadzadeh, M.; Sharifi Tehrani, A.; Sarani, Sh A.

2008-01-01

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Draft Genome Sequence of the Plant-Pathogenic Soil Fungus Rhizoctonia solani Anastomosis Group 3 Strain Rhs1AP.  

Science.gov (United States)

The soil fungus Rhizoctonia solani is a pathogen of agricultural crops. Here, we report on the 51,705,945 bp draft consensus genome sequence of R. solani strain Rhs1AP. A comprehensive understanding of the heterokaryotic genome complexity and organization of R. solani may provide insight into the plant disease ecology and adaptive behavior of the fungus. PMID:25359908

Cubeta, Marc A; Thomas, Elizabeth; Dean, Ralph A; Jabaji, Suha; Neate, Stephen M; Tavantzis, Stellos; Toda, Takeshi; Vilgalys, Rytas; Bharathan, Narayanaswamy; Fedorova-Abrams, Natalie; Pakala, Suman B; Pakala, Suchitra M; Zafar, Nikhat; Joardar, Vinita; Losada, Liliana; Nierman, William C

2014-01-01

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REAÇÃO DE CULTIVARES DO FEIJOEIRO COMUM ÀS PODRIDÕES RADICULARES CAUSADAS POR Rhizoctonia solani E Fusarium solani f. sp. phaseoli REACTION OF COMMON BEAN CULTIVARS TO ROOT ROT CAUSED BY Rhizoctonia solani AND Fusarium solani f. sp. phaseoli  

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Full Text Available

Rhizoctonia solani Kuhn é um fungo necrotrófico, habitante do solo, que ataca grande número de espécies vegetais. Em feijoeiro, R. solani pode induzir sintomas como tombamento, podridões de raízes e de colo da planta. Fusarium solani (Mart Sacc. f. sp. phaseoli (Burcholder ocorre em praticamente todas as regiões produtoras de feijão no Brasil e pode causar podridão radicular e morte das plantas. Neste trabalho, avaliou-se a reação de cultivares de feijoeiro comum às podridões radiculares causadas por R. solani e F. solani f. sp. phaseoli, em solo artificialmente infestado, em condições de casa de vegetação. O delineamento experimental foi inteiramente casualizado, com 24 tratamentos e quatro repetições. Utilizou-se solo Latassolo vermelho-escuro, infestado com 1,0 g de grãos de sorgo triturado e previamente infestado com R. solani para cada 1,4 kg de solo e para F. solani f. sp. phaseoli utilizaram-se oito gramas para cada 1,4 kg de solo. A avaliação da doença foi realizada 21 dias após o plantio, em plantas cujo sistema radicular foi cuidadosamente retirado e lavado em água corrente. A severidade da doença foi avaliada de acordo com escala de notas proposta por Abawi & Pastor-Corrales (1990. O comportamento das cultivares variou de acordo com o patógeno utilizado, ou seja, os genótipos reagiram diferentemente aos dois patógenos, sendo todas suscetíveis, mas com diferentes níveis de suscetibilidade. Entre as cultivares avaliadas, a cultivar Pérola mostrou ser a menos suscetível a R. solani, e Radiante, a menos suscetível a F. solani f. sp. phaseoli.

PALAVRAS-CHAVE: Phaseolus vulgaris; patógenos de raiz.

Rhizoctonia solani Kuhn is a necrotrophic fungus and soil inhabitant that attacks great number of vegetable species. In bean plants, R. solani can induce different symptoms including toppling, root and colon plant rottenness. Fusarium solani (Mart Sacc. f. sp. phaseoli (Burcholder occurs in practically all bean producing areas in Brazil and can cause root rots and death to bean plants. This study evaluated the reaction of commercial common bean cultivars growing in R. solani or F. solani f. sp. phaseoli infested soil, under green house conditions. The experimental design was entirely randomized, with 24 treatments and four replications. A Oxisol was infested with triturated sorghum grains that were previously colonized by R. solani (1.0 g/1.4 L of soil or F. solani f. sp phaseoli (8.0 g/1.4 L of soil. The disease evaluations were accomplished 21 days after planting. All plants were carefully removed, their root systems were washed in running water and the disease severity was evaluated according to Abawi & Pastor-Corrales (1990 scale for disease severity. The cultivar behavior ranged according to the inoculated pathogen, all cultivars were susceptible with different degrees of susceptibility. Among evaluated common bean cultivars Pérola was less susceptible to R. solani, and Radiante was less susceptible to F. solani f. sp. phaseoli.

KEY-WORDS: Phaseolus vulgaris; resistance, soil pathogen.

Murillo Lobo Júnior

2007-12-01

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Role of Biological Control on Some Physiological Aspects of Zea mays Infected by Rhizoctonia solani  

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Full Text Available The results revealed that treatment with either Trichoderma harzianum or Bacillus subtilis by soil inoculation or grain coating significantly increased the percentage of healthy seedlings as well as the length, fresh and dry weight of seedlings. Photosynthetic pigments content of the leaves significantly increased in absence of Rhizoctonia solani alone. The same almost applied to soluble sugar content, amino acid content or total nitrogen of the seedlings, though less apparent or insignificant when the grains were treated with B. subtilis before growing in soil treated with 3% R. solani. R. solani lowered the test elemental content of Zea mays seedlings, while the reverse was most prominent by sowing the grains in soil amended with R. solani and T. harzianum. The results also revealed that infestation by Rhizoctonia solani significantly lowered the length of the ears and weight of 100 grains. In the mean time the weight of 100 grains significantly dropped; a response that was hardly, if at all affected by implying R. solani with Bacillus subtilis or T. harzianum. The presence of the three microorganisms increased the fresh weight of the ears but the total count or weight of the grains was lowered. The presence of R. solani in soil lowered the lipid, total carbohydrates and protein content of corn flour. Meanwhile using the biological control agents T. harzianum or B. subtilis or both initiated the increase of these components.

Faten A. El-Daly

2006-01-01

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Reaction of faba bean genotypes to Rhizoctonia solani and resistance stability Reação de genótipos de fava a Rhizoctonia solani e estabilidade da resistência  

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Full Text Available The production of faba bean (Phaseolus lunatus is limited due to the occurrence of Rhizoctonia canker, caused by the fungus Rhizoctonia solani. In order to select materials with potential for use in faba beans breeding programs and/or disease integrated management, 72 genotypes were evaluated and also stability of the disease resistance in relation to different pathogen isolates, inoculum densities and soil type. The seeds were sown in soil infested with the pathogen by the addition of colonized substrate (rice grains. The evaluation of genotypes was done after 15 days, using a note scale to discriminate the genotypes into five reaction classes. None of the 72 genotypes showed immunity to R. solani and only four genotypes (F-42, F-49, F-53 and F-58 behaved as highly resistant. The reactions presented by these genotypes varied according to the R. solani isolate, inoculum density and soil used. The genotype F-58 showed more stable resistance to pathogen isolates and inoculum densities. The genotype F-53 showed resistance stability in soils collected in different locations, remaining highly resistant in all situations. The genotype F-58 did not show high resistance to only one tested soil. Therefore, the genotypes F-58 and F-53 are promising sources of resistance to R. solani and should be indicated in areas infested by the pathogen.A produção de fava (Phaseolus lunatus é limitada pela ocorrência da rizoctoniose, causada pelo fungo Rhizoctonia solani. Visando selecionar materiais com potencial de utilização nos programas de melhoramento e/ou no manejo integrado da doença, foram avaliados 72 genótipos de fava e verificada a estabilidade da resistência em relação a diferentes isolados do patógeno, densidades de inóculo e tipos de solo. As sementes foram plantadas em solo infestado com o patógeno pela incorporação de substrato (grãos de arroz colonizado. A avaliação dos genótipos foi realizada após 15 dias, com o auxílio de escala de notas, discriminando-os em cinco classes de reação. Nenhum dos 72 genótipos apresentou reação de imunidade a R. solani e apenas quatro genótipos (F-42, F-49, F-53 e F-58 comportaram-se como altamente resistentes. As reações apresentadas por esses genótipos variaram conforme o isolado de R. solani, a densidade de inóculo e o solo utilizado. O genótipo F-58 evidenciou maior estabilidade na resistência aos isolados do patógeno e densidades de inóculo. O genótipo F-53 demonstrou estabilidade da resistência em solos coletados em diferentes locais, mantendo alta resistência em todas as situações. O genótipo F-58 não demonstrou alta resistência em somente um solo. Portanto, os genótipos F-58 e F-53 constituem fontes promissoras de resistência a R. solani e devem ser preferidas em campos infestados pelo patógeno.

Iraildes P Assunção

2011-12-01

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Ultrastructural analysis of anastomosis group 9 of Rhizoctonia solani  

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The ultrastructure of R. solani AG-9 (S-21, ATCC 62804) was investigated with transmission electron microscopy (TEM). The most important characteristics were those related with cell wall thickness, cytoplasmic matrix composition, number of nuclei and nucleoli and secretory material production. The majority of examined hyphae showed lateral cell walls thinner than those recorded before. The cytoplasmic matrix consistently appeared differentiated into two classes, one formed by a highly electron dense granular fine material and the other one showing a coloidal substance of very low density which give these cells a 'tiger-like' aspect. The granular dense matrix always had abundant free ribosomes and usually surrounded the cytoplasmic organelles and the septal pore apparatus. The somatic cells showed up to 5 nuclei, some of which with three nucleoli. Masses of secretory material surrounded by membrane were regularly seen in the cytoplasm, with sizes similar to those of nuclei

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Some characteristics of isolates of Rhizoctonia solani from patch of wheat and barley  

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Full Text Available Rhizoctonia-like fungi were isolated from the roots of discased wheat and barley plants sampled from the centre and periphery of bare patches and from apparently healthy plants from outside of the patches. Of the isolates recovered. 89% were multinucleate and belonged to R. solani anastomosis groups: AG-8, AG-2-2 and AG-4. The remaining isolates were binucleate Rhizoctonia spp. The multinucleate isolates of R. solani were all pathogenic. All the binucleate isolates were non-pathogenic. The AG-8 isolates of R. solani were obtained mor? frequently from the plants within the patches than outside the patches. The highly virulent isolates of AG-8 were not found outside the patches. Isolates of anastomosis groups AG-2-2, AG-4 and saprotrophic isolates of AG-8 noted less frequently within the patches.

Helena Furga?-W?gorzycka

1998-06-01

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Reação de resistência de genótipos de tomateiro (Lycopersicum spp. à infecção por Rhizoctonia solani Kuhn Resistance reaction of tomato genotypes (Lycopersicum spp. to Rhizoctonia solani Kuhn  

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Full Text Available Dada a importância da tomaticultura no Brasil e das enfermidades que atacam esta cultura, da mesma forma que visando futuros estados em programas de melhoramento vegetal para resistência à patógenos, este trabalho teve por objetivos: avaliar o grau de patogenicidade de quatro isolados de Rhizoctonia solani obtidos de plantas doentes de tomateiro (RT, berinjelas (RB1 e RB2 e pimentão (RP, em viveiros, frente a 9 genótipos de tomateiros e avaliar a reação de resistência de 73 genótipos de tomateiros ao R. solani. Nos experimentos utilizou-se solo esterilizado, em condições de casa de vegetação. Para o experimento I, os isolados de R. solani, oriundos das plantas de tomateiro (RT e berinjela (RB, foram igualmente mais patogênicos que os isolados de berinjela (RB, e pimentão (RP, com relação aos 9 genótipos de tomateiro testados. Pode-se dizer que os isolados variaram em graus de agressividade. Quanto às reações de resistência a R. solani, observou-se que os diferentes genótipos não diferiram estatisticamente entre si. Com relação ao experimento II, entre os 73 genótipos de tomateiro (incluindo espécies selvagens, variedades nacionais e introduções, pode-se observar que houve grande variabilidade quanto a reação de resistência a R. solani (isolado do tomateiro - RT, com percentuais de sobrevivência de plantas variando de 91%, para a cultivar Quinck Pick, até 0% de sobrevivência para o genótipo LA-462. Não foi verificada imunidade em nenhum material avaliado e sim níveis de resistência, onde esta, expressa em percentagem de sobrevivência, ocorreu de uma maneira contínua, desde uma reação de suscetibilidade até altos níveis de resistência.The present study was undertaken with the following objectives: 1 to evaluate the level of pathogenicity of four Rhizoctonia solani isolates obtained from diseased tomato plants (RT, from eggplant (RB1 and RB2, and pepper (RP and tested on 9 tomato genotypes grown in experimental plots; and 2 evaluate the resistance reaction of 73 tomato genotypes to the pathogen. Experiments were performed in greenhouse using sterilized soil. In experiment I, R. solani isolates from RT and RB2 plants were identically more pathogenic RB1 and RP. In experiment II, wide variability in the resistance reaction to R. solani (isolated from a tomato plant - RT was observed among the 73 tomato genotypes (which included wild species, Brazilian varieties and introduced material, with percentage of plant survival ranging from 91% for the cultivar Quick Pick to 0% for the genotype LA-462. None of the materials tested showed immunity, but different levels of resistance were observed, ranging from susceptibility to high resistance, as expressed by the survival percentages.

A.M. Rodrigues Cassiolato

1994-12-01

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Estudio del antagonismo de algunas especies de Trichoderma sobre Fusarium Oxysporum y Rhizoctonia Solani Antagonism studies of Trichoderma sp.p.. with Fusarium oxysporum and Rhizoctonia solani  

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Full Text Available En este trabajo se estudió el antagonismo de algunos aislamientos del hongo Trichoderma obtenidos de suelos colornbianos en el control de Fusarium oxysporum y Rhizoctonia solani. En los ensayos "in vitre" se observó un marcado antagonismo entre las colonias de los aislamientos de Trichoderma sobre R. sotsni, con una reducción apreciable
del tamaño de la colonia y un antaqonismo menor sobre F. oxysporum. En los ensayos de parasitismo a nivel microscópico, se observó una gran interacción entre alqunos
de los aislamientos de T. harzianum y T. hamatum y el patógéno R. solani rnanifestado por el enrollamiento, penetración, fragmentación y lisis de las hifas del patoqeno.
Los aislamientos de Trichoderma causaron un retraso en la aparición de los síntomas, una reducción en la severidad de la
enfermedad. y un menor número de plantas enfermas ocasionadas por F. oxysporum f. sp, cucumerinum en pepino cohombro, y su efecto fue superior en todos los casos a la
aplicación del fungicida benomil. Los aislamientos del antagonista aumentaron la qerminación de las semillas, la emergencia y el tamaño de las plántulas y redujeron la severidad de la enfermedad ocasionada por R. solani en fríjol.Several experiments were conducted to study the antagonism of 17 isolates of Trichoderma from Colombian soils with Fusarium oxysporum and Rhizoctonia solani. In "in vitro" tests, a high antagonism between colonies was found being greater the antagonism of Trichoderma with R. solani. At the microscopic level it was observed a great interaction between T. harzianum and T. hamatum with R. solani in such a way that the hyphae of the pathogen showed coiling, penetration, fragmentation and lysis. The Trichoderma isolates caused reduction in the disease severity, in the incubation period and a lower number of diseased cucumber plants when they were inoeulated with F. oxysporum f. sp, cucumerinum and these effects were better than Benomyl application. The same Trichoderma isolates increased seed germination, emergence and seedling size of bean plants inoculated with R. solani. A reduction of the disease severity was also found.

Elias Ricardo

1989-12-01

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A simple and rapid nuclear staining method for Rhizoctonia solani Kuhn.  

Science.gov (United States)

We developed a modified staining technique using acridine orange to stain the nuclei of Rhizoctonia solani. Acridine orange solution was prepared in acetic acid buffer, pH 7.2. Staining for 15 min was critical for observing the nuclei. All of the isolates were found to be multinucleated. The nuclei appeared bright green with light orange background. This method is simple, rapid and reproducible. PMID:21745160

Seema, M; Punith, B D; Devaki, N S

2012-04-01

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Reaction of faba bean genotypes to Rhizoctonia solani and resistance stability / Reação de genótipos de fava a Rhizoctonia solani e estabilidade da resistência  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A produção de fava (Phaseolus lunatus) é limitada pela ocorrência da rizoctoniose, causada pelo fungo Rhizoctonia solani. Visando selecionar materiais com potencial de utilização nos programas de melhoramento e/ou no manejo integrado da doença, foram avaliados 72 genótipos de fava e verificada a est [...] abilidade da resistência em relação a diferentes isolados do patógeno, densidades de inóculo e tipos de solo. As sementes foram plantadas em solo infestado com o patógeno pela incorporação de substrato (grãos de arroz) colonizado. A avaliação dos genótipos foi realizada após 15 dias, com o auxílio de escala de notas, discriminando-os em cinco classes de reação. Nenhum dos 72 genótipos apresentou reação de imunidade a R. solani e apenas quatro genótipos (F-42, F-49, F-53 e F-58) comportaram-se como altamente resistentes. As reações apresentadas por esses genótipos variaram conforme o isolado de R. solani, a densidade de inóculo e o solo utilizado. O genótipo F-58 evidenciou maior estabilidade na resistência aos isolados do patógeno e densidades de inóculo. O genótipo F-53 demonstrou estabilidade da resistência em solos coletados em diferentes locais, mantendo alta resistência em todas as situações. O genótipo F-58 não demonstrou alta resistência em somente um solo. Portanto, os genótipos F-58 e F-53 constituem fontes promissoras de resistência a R. solani e devem ser preferidas em campos infestados pelo patógeno. Abstract in english The production of faba bean (Phaseolus lunatus) is limited due to the occurrence of Rhizoctonia canker, caused by the fungus Rhizoctonia solani. In order to select materials with potential for use in faba beans breeding programs and/or disease integrated management, 72 genotypes were evaluated and a [...] lso stability of the disease resistance in relation to different pathogen isolates, inoculum densities and soil type. The seeds were sown in soil infested with the pathogen by the addition of colonized substrate (rice grains). The evaluation of genotypes was done after 15 days, using a note scale to discriminate the genotypes into five reaction classes. None of the 72 genotypes showed immunity to R. solani and only four genotypes (F-42, F-49, F-53 and F-58) behaved as highly resistant. The reactions presented by these genotypes varied according to the R. solani isolate, inoculum density and soil used. The genotype F-58 showed more stable resistance to pathogen isolates and inoculum densities. The genotype F-53 showed resistance stability in soils collected in different locations, remaining highly resistant in all situations. The genotype F-58 did not show high resistance to only one tested soil. Therefore, the genotypes F-58 and F-53 are promising sources of resistance to R. solani and should be indicated in areas infested by the pathogen.

Iraildes P, Assunção; Liliane D, Nascimento; Mércia F, Ferreira; Francisco J, Oliveira; Sami J, Michereff; Gaus SA, Lima.

 
 
 
 
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Comparative analysis of putative pathogenesis-related gene expression in two Rhizoctonia solani pathosystems.  

Science.gov (United States)

Rhizoctonia solani, teleomorph Thanatephorus cucumeris, is a polyphagous necrotrophic plant pathogen of the Basidiomycete order that is split into 14 different anastomosis groups (AGs) based on hyphal interactions and host range. In this investigation, quantitative real-time PCR (qRT-PCR) techniques were used to determine potential pathogenicity factors of R. solani in the AG1-IA/rice and AG3/potato pathosystems. These factors were identified by mining for sequences of pathogen origin in a library of rice tissue infected with R. solani AG1-IA and comparing these sequences against the recently released R. solani AG3 genome. Ten genes common to both AGs and two specific to AG1-IA were selected for expression analysis by qRT-PCR. Results indicate that a number of genes are similarly expressed by AG1 and AG3 during the early stages of pathogenesis. Grouping of these pathogenicity factors based on relatedness of expression profiles suggests three key events are involved in R. solani pathogenesis: early host contact and infiltration, adjustment to the host environment, and pathogen proliferation through necrotic tissue. Further studies of the pathogenesis-associated genes identified in this project will enable more precise elucidation of the molecular mechanisms that allow for the widespread success of R. solani as a phytopathogen and allow for more targeted, effective methods of management. PMID:21909999

Rioux, Renee; Manmathan, Harish; Singh, Pratibha; de los Reyes, Benildo; Jia, Yulin; Tavantzis, Stellos

2011-12-01

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Biocontrol efficacy of different isolates of Trichoderma against soil borne pathogen Rhizoctonia solani.  

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In this study, the biocontrol abilities of water-soluble and volatile metabolites of three different isolates of Trichoderma (T. asperellum, T. harzianum and Trichoderma spp.) against soil borne plant pathogen Rhizoctonia solani were investigated both in vitro and in vivo. The results showed for the first time that mycelial growth inhibition of the pathogen was 74.4-67.8% with water-soluble metabolites as compared to 15.3-10.6% with volatile metabolites in vitro. In vivo antagonistic activity of Trichoderma isolates against R. solani was evaluated on bean plants under laboratory and greenhouse conditions. We observed that T. asperellum was more effective and consistent, lowering disease incidence up to 19.3% in laboratory and 30.5% in green house conditions. These results showed that three isolates of Trichoderma could be used as effective biocontrol agents against R. solani. PMID:25033669

Asad, Saeed Ahmad; Ali, Naeem; Hameed, Abdul; Khan, Sabaz Ali; Ahmad, Rafiq; Bilal, Muhammad; Shahzad, Muhammad; Tabassum, Ayesha

2014-01-01

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A novel postharvest rot of okra pods caused by Rhizoctonia solani in Brazil / Uma nova podridão pós-colheita de frutos de quiabo causada por Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Frutos de quiabo apresentando podridão e lesões marrons foram coletados em um supermercado de Brasília DF. O objetivo deste trabalho foi identificar o agente causal e comprovar o envolvimento do fungo como causador da doença (Postulados de Koch) e determinar algumas condições favoráveis à ocorrência [...] da doença em frutos de quiabo após a colheita. O patógeno foi identificado como Rhizoctonia solani baseado nas suas características morfológicas, como hifas marrons a ocre, com ramificações laterais em ângulos quase retos com constrições na base, células da hifa com 6-10 µm de largura com um septo perto da base. Cinco isolados foram obtidos dos frutos infectados e identificados como sendo do grupo de anastomose AG 1-IB. Frutos de quiabo cv. Santa Cruz 47 inoculados com discos de micélio de R. solani com e sem ferimentos e mantidos em câmaras úmidas, a 25 ºC, por sete dias ficaram completamente apodrecidos pelo patógeno, com cor marrom, enquanto somente os frutos com ferimentos mantidos a 12 ºC apresentaram lesões pequenas, variando de 0,6 a 1,0 mm de diâmetro. Em outro experimento, foi demonstrado que o patógeno foi capaz de crescer na superfície de diferentes materiais usados na confecção de embalagens de produtos hortícolas, como madeira de pinus, papelão corrugado, plástico, isopor e folhas de jornal mantidos em câmara úmida (24 ºC, 96 % UR). A ocorrência da doença está relacionada com manuseio pós-colheita inadequado, e a transmissão de propágulos do fungo junto com restos culturais ou partículas de solo. Este é o primeiro relato de R. solani causando podridão pós-colheita em frutos de quiabo no Brasil. Abstract in english Okra pods with unusual brown lesions and rot were collected in a local supermarket in Brasília DF. The objective of this paper was to characterize the causal agent, to fulfill Koch's postulates and to determine some conditions conducive to disease. The pathogen was identified as Rhizoctonia solani b [...] ased on morphological characteristics which fitted the fungus description, such as pale to brown hyphae, with nearly right-angled side branches constricted at the base, hyphal cells 6-10 µm wide with a septum near the base. Five isolates were obtained from infected pods and identified as AG 1-IB anastomosis group. Wounded or unwounded okra pods cv. Santa Cruz 47 were inoculated with mycelium disks of R. solani and kept in humid chambers at 12 ºC or 25 ºC. After seven days at 25 ºC, both wounded and unwounded pods were completely rotted and brown, while those kept at 12 ºC showed small lesions ranging from 0.6 to 1.0 mm only in wounded pods. The pathogen was able to grow in different materials used for assembling crates and packs of horticultural products, such as pinewood, corrugated carton, plastic, Styrofoam and newspaper sheets when kept in humid chambers (24 ºC, 96 % RH). The disease occurrence can be related to careless handling practices and to the transmission of R. solani propagules by infected plant debris or soil particles. This is the first report of Rhizoctonia solani causing postharvest rot in okra pods in Brazil.

Gilmar P., Henz; Carlos A., Lopes; Ailton, Reis.

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A novel postharvest rot of okra pods caused by Rhizoctonia solani in Brazil Uma nova podridão pós-colheita de frutos de quiabo causada por Rhizoctonia solani  

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Full Text Available Okra pods with unusual brown lesions and rot were collected in a local supermarket in Brasília DF. The objective of this paper was to characterize the causal agent, to fulfill Koch's postulates and to determine some conditions conducive to disease. The pathogen was identified as Rhizoctonia solani based on morphological characteristics which fitted the fungus description, such as pale to brown hyphae, with nearly right-angled side branches constricted at the base, hyphal cells 6-10 µm wide with a septum near the base. Five isolates were obtained from infected pods and identified as AG 1-IB anastomosis group. Wounded or unwounded okra pods cv. Santa Cruz 47 were inoculated with mycelium disks of R. solani and kept in humid chambers at 12 ºC or 25 ºC. After seven days at 25 ºC, both wounded and unwounded pods were completely rotted and brown, while those kept at 12 ºC showed small lesions ranging from 0.6 to 1.0 mm only in wounded pods. The pathogen was able to grow in different materials used for assembling crates and packs of horticultural products, such as pinewood, corrugated carton, plastic, Styrofoam and newspaper sheets when kept in humid chambers (24 ºC, 96 % RH. The disease occurrence can be related to careless handling practices and to the transmission of R. solani propagules by infected plant debris or soil particles. This is the first report of Rhizoctonia solani causing postharvest rot in okra pods in Brazil.Frutos de quiabo apresentando podridão e lesões marrons foram coletados em um supermercado de Brasília DF. O objetivo deste trabalho foi identificar o agente causal e comprovar o envolvimento do fungo como causador da doença (Postulados de Koch e determinar algumas condições favoráveis à ocorrência da doença em frutos de quiabo após a colheita. O patógeno foi identificado como Rhizoctonia solani baseado nas suas características morfológicas, como hifas marrons a ocre, com ramificações laterais em ângulos quase retos com constrições na base, células da hifa com 6-10 µm de largura com um septo perto da base. Cinco isolados foram obtidos dos frutos infectados e identificados como sendo do grupo de anastomose AG 1-IB. Frutos de quiabo cv. Santa Cruz 47 inoculados com discos de micélio de R. solani com e sem ferimentos e mantidos em câmaras úmidas, a 25 ºC, por sete dias ficaram completamente apodrecidos pelo patógeno, com cor marrom, enquanto somente os frutos com ferimentos mantidos a 12 ºC apresentaram lesões pequenas, variando de 0,6 a 1,0 mm de diâmetro. Em outro experimento, foi demonstrado que o patógeno foi capaz de crescer na superfície de diferentes materiais usados na confecção de embalagens de produtos hortícolas, como madeira de pinus, papelão corrugado, plástico, isopor e folhas de jornal mantidos em câmara úmida (24 ºC, 96 % UR. A ocorrência da doença está relacionada com manuseio pós-colheita inadequado, e a transmissão de propágulos do fungo junto com restos culturais ou partículas de solo. Este é o primeiro relato de R. solani causando podridão pós-colheita em frutos de quiabo no Brasil.

Gilmar P. Henz

2007-06-01

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Factors affecting antifungal activity of Streptomyces philanthi RM-1-138 against Rhizoctonia solani.  

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Sheath blight disease of rice caused by Rhizoctonia solani Kühn is economically important disease in most of the world's rice growing areas. The disease causes severe yield losses of >20% of rice in Thailand. Our previous investigation reported the antifungal activity of Streptomyces philanthi RM-1-138 against R. solani PTRRC-9. In this study, glucose yeast-malt extract medium, initial pH of 7.5 and a temperature of 30 °C were found to be optimum for both cell growth and antifungal activity of S. philanthi RM-1-138. The inhibition of 94 and 100% on the growth of R. solani PTRRC-9 were achieved from the antifungal metabolites of the 6 and 9-days-old culture filtrates of S. philanthi RM-1-138, respectively. Heat treatment on the culture filtrate had slight effect on its antifungal activity. The culture broth demonstrated higher antifungal activity on growth of R. solani PTRRC-9 (90.4%) than the culture filtrate (31.5%) and its effective dose was at 0.1% (v/v). The present results indicated the possibilities of using either the culture broth or culture filtrate of S. philanthi RM-1-138 to inhibit growth of R. solani PTRRC-9. PMID:23839715

Boukaew, Sawai; Prasertsan, Poonsuk

2014-01-01

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Diversity of Rhizoctonia solani associated with pulse crops in different agro-ecological regions of India.  

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Four hundred seventy Rhizoctonia solani isolates from different leguminous hosts originating from 16 agro-ecological regions of India covering 21 states and 72 districts were collected. The disease incidence caused by R. solani varied from 6.8 to 22.2 % in the areas surveyed. Deccan plateau and central highlands, hot sub-humid ecoregion followed by northern plain and central highlands and hot semi-arid ecoregion showed the highest disease incidence. R. solani isolates were highly variable in growth diameter, number, size and pattern of sclerotia formation as well as hyphal width. The isolates obtained from aerial part of the infected plants showing web blight symptoms produced sclerotia of 1-2 mm in size whereas, the isolates obtained from infected root of the plants showing wet root rot symptoms produced microsclerotia (solani isolates showed solani associated with the pulse crops. The frequency (25.6 %) of AG3 was the highest followed by AG2-3 (20.9 %) and AG5 (17.4 %). The cropping sequence of rice/sorghum/wheat-chickpea/mungbean/urdbean/cowpea/ricebean influenced the dominance of AG1 (16.3 %). Phylogenetic analysis utilizing ITS-5.8S rDNA gene sequences indicated high level of genetic similarity among isolates representing different AGs, crops and regions. ITS groups did not correspond to the morphological characters. The sequence data from this article has been deposited with NCBI data libraries with JF701707 to JF701795 accession numbers. PMID:24399024

Dubey, Sunil C; Tripathi, Aradhika; Upadhyay, Balendu K; Deka, Utpal K

2014-06-01

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Crop Residue Affects Rhizoctonia solani Population Dynamics and Seedling Blight of Canola  

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Full Text Available Seedling blight caused by Rhizoctonia solani Kühn substantially reduces stand establishment and seed yield of canola (Brassica napus L. in western Canada. The effect of crop residue on soil populations of R. solani and canola seedling blight was examined under field, greenhouse and laboratory conditions. Field plots were established with inoculation or noninoculation with R. solani as the main plot and barley, canola, oat and field pea residues as the sub-plots. Soil samples were collected from each subplot for analysis in a greenhouse bioassay and laboratory assay of R. solani population before seeding canola. The crop residue effect was not significant. Under inoculation with R. solani, the yield was consistently greater when canola was grown on barley residue compared to the canola residue over two-year trials, although oat and pea residue contributed to greater yield. Without inoculation, canola yield was greatest when grown on barley residue, intermediate on oat and pea and the least on canola in the first trial and in the second trial greater yield was obtained on barley and oat residues compared to other residues. In the greenhouse bioassay, canola seedling emergence was greater, while damping off and root rot were less severe, following barley or oat compared to canola or field pea in both inoculated and non-inoculated treatments. Populations of Rhizoctonia were lower following barley or oat relative to canola or field pea. Crop rotation and incorporation of barley or oat residue between canola crops may be a useful strategy to reduce seedling blight of canola.

H.U. Ahmed

2014-01-01

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Endophytic Bacillus Species Confer Increased Resistance in Cotton Against Damping off Disease Caused by Rhizoctonia solani  

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Full Text Available Endophytic bacterial strains were evaluated for their efficacy against the damping off disease caused by Rhizoctonia solani in cotton. Among hundred and three endophytic bacterial strains isolated, two strains (Bacillus sp. strains EPCO102 and EPCO16 significantly increased plant growth and inhibited the mycelial growth of Rhizoctonia solani in vitro conditions. The efficacy of talc-based bioformulation of endophytic bacterial strains, EPCO102, EPCO16 and Pseudomonas fluorescens strain Pf1 amended with and without chitin in inducing systemic resistance was tested against damping off disease under greenhouse conditions. The application of the bioformulation through seed, soil and foliar spray significantly reduced disease incidence under greenhouse conditions. The amendment of chitin in the formulation further reduced the disease incidence. EPCO102, EPCO16 and Pf1 strain along with chitin treatment was recorded 46.7, 53.3 and 40.0% damping-off incidence compared to control 83.3%. Treatment with the endophytic bacterial bioformulation increased the levels of the defence-related enzymes chitinase, ?-1,3-glucanase, peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase and phenol in cotton plants which had been challenged with R. solani. In addition to plant growth and antibiosis, endophytic bacterial strains enhanced the resistance in plants through the induction of defense enzymes in cotton plants.

L. Rajendran

2008-01-01

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Genetic diversity of Rhizoctonia solani associated with potato tubers in France.  

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The soilborne fungus Rhizoctonia solani is a pathogen of many plants and causes severe damage in crops around the world. Strains of R. solani from the anastomosis group (AG) 3 attack potatoes, leading to great yield losses and to the downgrading of production. The study of the genetic diversity of the strains of R. solani in France allows the structure of the populations to be determined and adapted control strategies against this pathogen to be established. The diversity of 73 French strains isolated from tubers grown in the main potato seed production areas and 31 strains isolated in nine other countries was assessed by phylogenetic analyses of (i) the internal transcribed spacer sequences (ITS1 and ITS2) of ribosomal RNA (rRNA), (ii) a part of the gene tef-1? and (iii) the total DNA fingerprints of each strain established by amplified fragment length polymorphism (AFLP). The determination of the AGs of R. solani based on the sequencing of the ITS region showed three different AGs among our collection (60 AG 3 PT, 8 AG 2-1 and 5 AG 5). Grouping of the strains belonging to the same AG was confirmed by sequencing of the gene tef-1? used for the first time to study the genetic diversity of R. solani. About 42% of ITS sequences and 72% of tef-1? sequences contained polymorphic sites, suggesting that the cells of R. solani strains contain several copies of ITS and the tef-1? gene within the same nucleus or between different nuclei. Phylogenetic trees showed a greater genetic diversity within AGs in tef-1? sequences than in ITS sequences. The AFLP analyses showed an even greater diversity among the strains demonstrating that the French strains of R. solani isolated from potatoes were not a clonal population. Moreover there was no relationship between the geographical origins of the strains or the variety from which they were isolated and their genetic diversity. PMID:21642342

Fiers, Marie; Edel-Hermann, Véronique; Héraud, Cécile; Gautheron, Nadine; Chatot, Catherine; Le Hingrat, Yves; Bouchek-Mechiche, Karima; Steinberg, Christian

2011-01-01

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Dried powders of velvetbean and pine bark added to soil reduce Rhizoctonia solani-induced disease on soybean Pós secos de mucuna e casca de pinus adicionados ao solo reduzem a doença causada por Rhizoctonia solani em soja  

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Diseases induced by Rhizoctonia solani, like damping-off and root and stem rot on soybean (Glycine max), are a serious problem around the world. The addition of some organic material to soil is an alternative control for these diseases. In this study, benzaldehyde and dried powders of kudzu (Pueraria lobata), velvetbean or mucuna (Mucuna deeringiana), and pine bark (Pinus spp.) were used in an attempt to improve soybean plant growth and to reduce the disease R. solani (AG-4) causes on soybean...

Blum, Luiz E. B.; Rodrígo Rodríguez-Kábana

2006-01-01

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Solarização do solo em casa-de-vegetação e campo para o controle de Rhizoctonia solani AG-4 Soil solarization under greenhouse and field conditions to the control of Rhizoctonia solani AG-4  

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Os cultivos em ambientes protegidos apresentaram uma grande expansão na década de 1990 no Brasil. O solo desses locais pode, por ser intensa e sucessivamente cultivado, se tornar infestado por patógenos como Rhizoctonia solani, responsável por tombamento e podridão de raízes em muitas espécies de plantas. O presente trabalho avaliou o emprego da solarização, dentro e fora de uma casa-de-vegetação vedada com plástico transparente, para o controle de R. solani. Quatro experimentos f...

Flávia Rodrigues Alves Patrício; Hiroshi Kimati; João Tessarioli Neto; Ademir Petenatti; Benedito De Camargo Barros

2007-01-01

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Rhizoctonia root rot (Rhizoctoni solani K ü h n of sugar beet in province Vojvodina  

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Full Text Available Sugar beet root rot appears regularly each year, but its intensity depends on agro ecological conditions. The predominant causers of root rot in Vojvodina are fungi from Fusarium genus and species Macrophomina phaseolina. Over the last couple of years, more intense occurrence of Rhizoctonia root rot has been observed. Rhizoctonia solani, the causal agent of root rot is present in sugar beet fields. During 2000-2005, on the territory of Vojvodina, the frequency of Rhizoctonia solani in phytopathological isolations from rotted sugar beet roots was between 0,0-18,2%. The intensity of the disease depends on localities, agro ecological conditions and genotypes. Symptoms of Rhizoctonia root rot were registered at some localities in all regions of Vojvodina: Srem, Banat and Ba?ka. The disease appearance is above all local. It occurs in small patches, on heavy, non-structured soil and on depressed wet parts of plots. Individual diseased plants can be found during July. Brown rot appears on sugar beet roots, with dried tissue on surface, which is present on the tail as well as on the middle part and the head of root. Tissues with described symptoms are deeper regarding the healthy part of root. On vertical root section, the necrotic changes are clearly visible comparing to tissue section without symptoms. The heavily infected tissue forms fissures on roots in most cases. Besides the above-mentioned symptoms on roots, the plant wilting and leaf handle necrosis as well as leaf dying are also observed. When rot spreads to the whole root head, plants quickly die.

Stojšin Vera B.

2006-01-01

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Seed disinfection effect of atmospheric pressure plasma and low pressure plasma on Rhizoctonia solani.  

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Gas plasma generated and applied under two different systems, atmospheric pressure plasma and low pressure plasma, was used to investigate the inactivation efficacy on the seedborne pathogenic fungus, Rhizoctonia solani, which had been artificially introduced to brassicaceous seeds. Treatment with atmospheric plasma for 10 min markedly reduced the R. solani survival rate from 100% to 3% but delayed seed germination. The low pressure plasma treatment reduced the fungal survival rate from 83% to 1.7% after 10 min and the inactivation effect was dependent on the treatment time. The seed germination rate after treatment with the low pressure plasma was not significantly different from that of untreated seeds. The air temperature around the seeds in the low pressure system was lower than that of the atmospheric system. These results suggested that gas plasma treatment under low pressure could be effective in disinfecting the seeds without damaging them. PMID:24975415

Nishioka, Terumi; Takai, Yuichiro; Kawaradani, Mitsuo; Okada, Kiyotsugu; Tanimoto, Hideo; Misawa, Tatsuya; Kusakari, Shinichi

2014-01-01

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Screening of bioantagonistic bacteria for biocontrol agent of Rhizoctonia solani and surfactin producer  

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Full Text Available The objective of this research was to screen 31 of bacteria isolates that have potency to control Rhizoctonia solani growth and isolates capability to produce surfactin. R. solani growth inhibition was performed uses paper discs containing a 5 days cultivation of isolates culture. Surfactin activity assay was performed on LB agar medium. Results of the screening showed that the highest growth inhibition was obtained for isolates code 54 (96.43%, KC4 (93.45%, and 163 (93.19%. All of the isolates were cooproducer of surfactin and iturin, and the highest biosurfactan index was obtained for isolate KB2 (3.91.The four potential isolates were identified, as Bacillus pantotheinticus (isolate 54 and isolate 163, Bacillus brevis (isolateKC4, and Bacillus sp(isolate KB2.

YULIAR

2008-04-01

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Determination of Optimum Cultivation Conditions on the Production of Inulinase from Rhizoctonia solani  

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Full Text Available Rhizoctonia solani isolated from Tekirdag-Turkey soil, was found to produce a very active inulinase enzyme. The optimum conditions for enzyme production were determined. Maximum growth was observed at 45°C while the highest inulinase production was determined at 40°C. The best inulinase production was observed at an initial medium pH 6.0 and on the first day of cultivation time. Inulin and Jerusalem artichoke powder as carbon source were the most effective on production of inulinase from R. solani. The highest productivity was recorded in the presence of 10 mM NH4H2PO4+10 mM NH4NO3 as nitrogen source.

Figen Ertan

2003-01-01

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Randomly Amplified Polymorphic DNA of Trichoderma isolates and antagonism against Rhizoctonia solani  

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Full Text Available Random Amplified Polymorphic DNA (RAPD procedure was used to examine the genetic variability among fourteen isolates of Trichoderma and their ability to antagonize Rhizoctonia solani using a dual-culture assay for correlation among RAPD products and their hardness to R. solani. Seven oligodeoxynucleotide primers were selected for the RAPD assays which resulted in 197 bands for 14 isolates of Trichoderma. The data were entered into a binary matrix and a similarity matrix was constructed using DICE similarity (SD index. A UPGMA cluster based on SD values was generated using NTSYS (Numerical Taxonomy System, Applied Biostatistics computer program. A mean coefficient of similarity obtained for pairwise comparisons among the most antagonics isolates was around 40%. The results presented here showed that the variability among the isolates of Trichoderma was very high. No relationship was found between the polymorphism showed by the isolates and their hardness, origin and substrata.

Góes Larissa Brandão

2002-01-01

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Postharvest dark skin spots in potato tubers are an oversuberization response to Rhizoctonia solani infection.  

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Israeli farmers export 250,000 tons of potato tubers annually, ?40,000 tons of which are harvested early, before skin set. In recent years, there has been an increase in the occurrence of dark skin spots on early-harvested potato tubers ('Nicola') packed in large bags containing peat to retain moisture. The irregular necrotic spots form during storage and overseas transport. Characterization of the conditions required for symptom development indicated that bag temperature after packing is 11 to 13°C and it reaches the target temperature (8°C) only 25 days postharvest. This slow decrease in temperature may promote the establishment of pathogen infection. Isolates from typical lesions were identified as Rhizoctonia spp., and Koch's postulates were completed with 25 isolates by artificial inoculation performed at 13 to 14°C. Phylogenetic analysis, using the internal transcribed spacer sequences (ITS1 and ITS2) of rDNA genes, assigned three isolates to anastomosis group 3 of Rhizoctonia solani. Inoculation of wounded tubers with mycelium of these R. solani isolates resulted in an oversuberization response in the infected area. With isolate Rh17 of R. solani, expression of the suberin biosynthesis-related genes StKCS6 and CYP86A33 increased 6.8- and 3.4-fold, respectively, 24 h postinoculation, followed by a 2.9-fold increase in POP_A, a gene associated with wound-induced suberization, expression 48 h postinoculation, compared with the noninoculated tubers. We suggest that postharvest dark spot disease is an oversuberization response to R. solani of AG-3 infection that occurs prior to tuber skin set. PMID:21391824

Buskila, Yossi; Tsror Lahkim, Leah; Sharon, Michal; Teper-Bamnolker, Paula; Holczer-Erlich, Orly; Warshavsky, Shimon; Ginzberg, Idit; Burdman, Saul; Eshel, Dani

2011-04-01

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Biological Control of Potato Isolate of Rhizoctonia solani by Streptomyces olivaceus Strain 115  

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Full Text Available This is the first report of antifungal activity of Iranian actinomycete isolates against Rhizoctonia solani Kuhn AG-3 (Teleomorph: Thanatephorus cucumeris [(Frank Donk]. Biological control offers an environmentally friendly alternative to the use of antimicrobials for controlling plant diseases. A collection of about 200 actinomycete strains was screened for the ability to produce metabolites that inhibit R. solani growth in vitro. The Streptomyces olivaceus strain 115 showed strong in vitro antagonistic activity against R. solani in agar disc and Well-diffusion methods by producing extracellular antifungal metabolites. The strain No. 115 was propagated in submerged cultures and active crude was prepared upon which some biological characterization performed. The active metabolite(s is polar, soluble in H2O and methanol but insoluble in chloroform, dichloromethane or hexane. Thermal inactivation point of active phase of S. olivaceus strain 115 was 80?C. Antifungal active phase of S. olivaceus strain 115 tolerate range of pH (6-9. Antifungal gene from strain 115 may be a useful candidate for genetic engineering of agriculturally important crop for increased tolerance against R. solani.

S. Shahrokhi

2005-01-01

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Effect of mycorrhization on the accumulation of rishitin and solavetivone in potato plantlets challenged with Rhizoctonia solani.  

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The effect of colonization with the vesicular-arbuscular mycorrhizal fungus Glomus etunicatum on the content of rishitin and solavetivone was determined in potato plants cv. Goldrush challenged with Rhizoctonia solani. Mycorrhization stimulated significantly the accumulation of both phytoalexins in roots of plantlets challenged with R. solani but did not influence phytoalexin levels in non-challenged plantlet roots. No accumulation of solavetivone or rishitin was detected in shoots. In Petri dish bioassays, rishitin and solavetivone inhibited mycelial growth of R. solani. PMID:14505123

Yao, M K; Désilets, H; Charles, M T; Boulanger, R; Tweddell, R J

2003-12-01

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Diversidade genética de isolados de Rhizoctonia solani coletados em feijão-caupi no Estado de Roraima Genetic diversity of Rhizoctonia solani isolates collected from Cowpea in the State of Roraima  

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Full Text Available O feijão-caupi (Vigna unguiculata é uma das principais fontes de proteína para a população de baixa renda, principalmente nas Regiões Norte e Nordeste do Brasil. Esta leguminosa é suscetível a várias doenças incluindo a mela ou murcha-da-teia-micélica, cujo agente causal é o fungo Rhizoctonia solani (teleomorfo: Thanatephorus cucumeris. Embora Rhizoctonia solani seja um agente causal de doença muito importante, no Brasil inexiste qualquer informação sobre as características de seus isolados associados ao feijão-caupi. O objetivo do presente estudo foi avaliar, utilizando-se das técnicas Random Amplified Polymorphic DNA (RAPD e RFLP-ITS (Internal Transcribed Spacer, a diversidade genética de isolados de R. solani coletados de plantas de feijão-caupi oriundas da região de cerrado e de mata do Estado de Roraima. Pelos resultados obtidos pode-se concluir que existe diversidade genética em R.. solani coletada de feijão-caupi e que os dois métodos moleculares utilizados foram eficientes em avaliar a divergência genética deste patógeno.Cowpea (Vigna unguiculata is one of the most important sources of protein for people with low incomes in Northern and Northeastern Brazil. Cowpea is susceptible to several diseases, including web blight caused by the fungus Rhizoctonia solani (teleomorph Thanatephorus cucumeris. Although R. solani is a very important disease agent, in Brazil there is no information on isolate characteristics when this fungus is associated with cowpea. The objective of this study was to evaluate, using Random Amplified Polymorphic DNA (RAPD and RFLP-ITS (Internal Transcribed Spacer techniques, the genetic diversity of R. solani isolates collected in the State of Roraima from cowpea cultivated under 'savannah' and 'forest' ecosystems. From the results it was possible to demonstrate genetic diversity among R. solani isolates and to prove that both molecular techniques used were efficient in evaluating it.

Aloísio Sartorato

2006-06-01

 
 
 
 
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DNA Microsatellite Analysis of Kenyan Isolates of Rhizoctonia solani from Common Bean (Phaseolus vulgaris L.  

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Full Text Available Seven hundred and fifty bean plant samples with root rot symptoms were collected from farmers' fields during two surreys carried out in Embu district, Kenya. Various fungal pathogens were isolated in the laboratory from these samples; among them were 50 isolates of Rhizoctonia solani, which were subjected to pathogenicity tests in a glasshouse. Thirty-six isolates of R. solani obtained from beans with root rots were subjected to DNA microsatellite analysis. Five isolates of R. solani that cause black scarf of potatoes (Solanum tuberosum L. were also analysed alongside those from the beans. A total of 50 alleles were detected when six microsatellite loci were typed in the 41 samples, with the mean of 8.33 and a range of 3 at locus RB23 to 19 at locus AF513014. The smallest allele size was 129 basepair at locus RE102 and the largest was 297 basepair at locus AY212027. Microsatellite analysis showed a moderate variation among the isolates from different agro-ecological zones and administrative boundaries (divisions. Phylogenetic analysis revealed 3 major clusters within the population of 41 isolates of R. solani from Kenya. Clusters 1, 2 and 3 had 15, 10 and 75% isolates, respectively. However, cluster 3 had 4 sub-clusters and cluster 1 had 2 sub-clusters, while cluster 2 did not have a sub-cluster. There was no relationship between microsatellites and geographical origin of the isolates. This is the first study on the genetic diversity of R. solani using DNA microsatellite analysis in Kenya.

A.W. Mwang`Ombe

2007-01-01

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Biological control of Rhizoctonia solani in tomatoes with Trichoderma harzianum mutants  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Biocontrol of Rhizoctonia solani in tomatoes cultivated under greenhouse and field conditions was analyzed using the Trichoderma harzianum mutants Th650-NG7, Th11A80.1, Th12A40.1, Th12C40.1 and Th12A10.1 and ThF2-1, respectively. Their innocuousness on tomato cultivars 92.95 and Gondola (greenhouse [...] assays), and on cultivar Fortaleza (field assays) was established. Alginate pellets (1.7 g pellets/L soil) containing c.a1 x 10(5) colony forming units (cfu)/g pellet were applied to a soil previously inoculated with R. solani at transplant (greenhouse) or to a naturally infected soil (field). Controls considered parental wild strains, a chemical fungicide and no additions. Th11A 80.1, Th12A10.1 and Th650-NG7 prevented the 100% mortality of tomato plants cv. 92.95 caused by R. solani, and the 40% mortality in tomato plants cv. Gondola (greenhouse assays). Mortality reduction was reflected in canker level lessening and in plant parameters increases (development, fresh and dry weights). A different degree of susceptibility of tomato plants was observed, being Gondola cv. more resistant than 92.95 cv. to infection in a soil previously inoculated with R. solani. Tomato plants of cv. Fortaleza did not show mortality in naturally infected soils (field assays), where the mutant ThF2-1 reduced significantly the canker level caused by R. solani.

Jaime, Montealegre; Luis, Valderrama; Soledad, Sánchez; Rodrigo, Herrera; Ximena, Besoain; Luz María, Pérez.

2010-03-15

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Reação de cultivares de feijão-caupi à mela (Rhizoctonia solani) em Roraima / Reaction of cowpea cultivars to web blight (Rhizoctonia solani) in Roraima, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Em Roraima, uma das principais doenças que incidem na cultura do feijão-caupi (Vigna unguiculata) é a mela causada pelo fungo Thanatephorus cucumeris (anamorfo Rhizoctonia solani). Este trabalho teve como objetivo avaliar a reação a esta doença de dez cultivares de feijão-caupi em área de cerrado em [...] Roraima, em dois anos consecutivos. As cultivares de porte ereto utilizadas foram BRS-Mazagão, IT86D-719, Vita-7 (Epace-1), BR02-Bragança, Pitiúba, e as de porte prostrado, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato e Canapuzinho. Os ensaios foram instalados em 2005 e 2006, utilizando-se o delineamento experimental em blocos completos casualizados com cinco tratamentos e quatro repetições. Avaliou-se, semanalmente, a porcentagem de área foliar lesionada para a obtenção da área baixo da curva de progresso da doença. Pelos resultados obtidos verificou-se que os genótipos de porte prostrado apresentaram menor severidade do que os de porte ereto, indicando uma relação da arquitetura da planta com a resistência à mela. As cultivares de porte prostrado, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato e Canapuzinho, e as de porte ereto, BRS-Mazagão, Pitiúba e BR03-Bragança, foram as mais resistentes à mela e podem ser recomendadas para áreas com histórico de incidência da doença. Abstract in english Web blight caused by the fungus Thanatephorus cucumeris (Rhizoctonia solani) is one of most important diseases of cowpea (Vigna unguiculata) in the state of Roraima, Brazil. Web blight severity for ten cowpea cultivars was evaluated in Roraima in two consecutive years. The erect cowpea cultivars BRS [...] -Mazagão, IT86D-719, Vita-7 (Epace-1), BR02-Bragança and Pitiúba, as well as the prostrate cultivars BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, were used. The experiment was conducted during 2005 and 2006 in a complete randomized block design with five treatments and four replications. The percentage of diseased foliage was evaluated once a week and the data were used to calculate the area under the disease progress curve. Disease severity was lower on prostrate cultivars indicating a relationship between plant architecture and web blight resistance. The prostrate cultivars, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, and erect cultivars, BRS-Mazagão, Pitiúba and BR03-Bragança, were more resistant to web blight and can be recommended for planting in areas where the disease is known to occur.

Kátia de Lima, Nechet; Bernardo A., Halfeld-Vieira.

2007-10-01

64

Reação de cultivares de feijão-caupi à mela (Rhizoctonia solani) em Roraima / Reaction of cowpea cultivars to web blight (Rhizoctonia solani) in Roraima, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Em Roraima, uma das principais doenças que incidem na cultura do feijão-caupi (Vigna unguiculata) é a mela causada pelo fungo Thanatephorus cucumeris (anamorfo Rhizoctonia solani). Este trabalho teve como objetivo avaliar a reação a esta doença de dez cultivares de feijão-caupi em área de cerrado em [...] Roraima, em dois anos consecutivos. As cultivares de porte ereto utilizadas foram BRS-Mazagão, IT86D-719, Vita-7 (Epace-1), BR02-Bragança, Pitiúba, e as de porte prostrado, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato e Canapuzinho. Os ensaios foram instalados em 2005 e 2006, utilizando-se o delineamento experimental em blocos completos casualizados com cinco tratamentos e quatro repetições. Avaliou-se, semanalmente, a porcentagem de área foliar lesionada para a obtenção da área baixo da curva de progresso da doença. Pelos resultados obtidos verificou-se que os genótipos de porte prostrado apresentaram menor severidade do que os de porte ereto, indicando uma relação da arquitetura da planta com a resistência à mela. As cultivares de porte prostrado, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato e Canapuzinho, e as de porte ereto, BRS-Mazagão, Pitiúba e BR03-Bragança, foram as mais resistentes à mela e podem ser recomendadas para áreas com histórico de incidência da doença. Abstract in english Web blight caused by the fungus Thanatephorus cucumeris (Rhizoctonia solani) is one of most important diseases of cowpea (Vigna unguiculata) in the state of Roraima, Brazil. Web blight severity for ten cowpea cultivars was evaluated in Roraima in two consecutive years. The erect cowpea cultivars BRS [...] -Mazagão, IT86D-719, Vita-7 (Epace-1), BR02-Bragança and Pitiúba, as well as the prostrate cultivars BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, were used. The experiment was conducted during 2005 and 2006 in a complete randomized block design with five treatments and four replications. The percentage of diseased foliage was evaluated once a week and the data were used to calculate the area under the disease progress curve. Disease severity was lower on prostrate cultivars indicating a relationship between plant architecture and web blight resistance. The prostrate cultivars, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, and erect cultivars, BRS-Mazagão, Pitiúba and BR03-Bragança, were more resistant to web blight and can be recommended for planting in areas where the disease is known to occur.

Kátia de Lima, Nechet; Bernardo A., Halfeld-Vieira.

65

Reação de cultivares de feijão-caupi à mela (Rhizoctonia solani em Roraima Reaction of cowpea cultivars to web blight (Rhizoctonia solani in Roraima, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available Em Roraima, uma das principais doenças que incidem na cultura do feijão-caupi (Vigna unguiculata é a mela causada pelo fungo Thanatephorus cucumeris (anamorfo Rhizoctonia solani. Este trabalho teve como objetivo avaliar a reação a esta doença de dez cultivares de feijão-caupi em área de cerrado em Roraima, em dois anos consecutivos. As cultivares de porte ereto utilizadas foram BRS-Mazagão, IT86D-719, Vita-7 (Epace-1, BR02-Bragança, Pitiúba, e as de porte prostrado, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato e Canapuzinho. Os ensaios foram instalados em 2005 e 2006, utilizando-se o delineamento experimental em blocos completos casualizados com cinco tratamentos e quatro repetições. Avaliou-se, semanalmente, a porcentagem de área foliar lesionada para a obtenção da área baixo da curva de progresso da doença. Pelos resultados obtidos verificou-se que os genótipos de porte prostrado apresentaram menor severidade do que os de porte ereto, indicando uma relação da arquitetura da planta com a resistência à mela. As cultivares de porte prostrado, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato e Canapuzinho, e as de porte ereto, BRS-Mazagão, Pitiúba e BR03-Bragança, foram as mais resistentes à mela e podem ser recomendadas para áreas com histórico de incidência da doença.Web blight caused by the fungus Thanatephorus cucumeris (Rhizoctonia solani is one of most important diseases of cowpea (Vigna unguiculata in the state of Roraima, Brazil. Web blight severity for ten cowpea cultivars was evaluated in Roraima in two consecutive years. The erect cowpea cultivars BRS-Mazagão, IT86D-719, Vita-7 (Epace-1, BR02-Bragança and Pitiúba, as well as the prostrate cultivars BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, were used. The experiment was conducted during 2005 and 2006 in a complete randomized block design with five treatments and four replications. The percentage of diseased foliage was evaluated once a week and the data were used to calculate the area under the disease progress curve. Disease severity was lower on prostrate cultivars indicating a relationship between plant architecture and web blight resistance. The prostrate cultivars, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, and erect cultivars, BRS-Mazagão, Pitiúba and BR03-Bragança, were more resistant to web blight and can be recommended for planting in areas where the disease is known to occur.

Kátia de Lima Nechet

2007-10-01

66

Promotion of growth and control of damping-off (Rhizoctonia solani) of greenhouse tomatoes amended with vermicompost  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: English Abstract in english The pathogen Rhizoctonia solani (teleomorph Tanatephorus cucumeris) can affect tomatoes germination and emergence and cause basal rot of seedlings. It is generally accepted that composts suppress plant diseases, improve soil nutrient availability and stimulate plant growth. However, no reports have [...] been found on the simultaneous evaluation of vermicompost as plant growth promoter and suppressive to damping-off caused by R. solani on tomatoes. This research evaluated the suppressive effects of different concentrations of vermicompost against R. solani and the ability of vermicompost to promote tomato seedlings growth. The microbial composition of the substratum was explored. Thirty six microorganisms were isolated, 13 of which were antagonic to R.solani in vitro. The addition of 25 to 100% of vermicompost promoted seedlings growth and prevented damping-off caused by R. solani.

MC, Rivera; ER, Wright; MV, López; D, Garda; MY, Barragué.

2004-12-01

67

Promotion of growth and control of damping-off (Rhizoctonia solani) of greenhouse tomatoes amended with vermicompost  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: English Abstract in english The pathogen Rhizoctonia solani (teleomorph Tanatephorus cucumeris) can affect tomatoes germination and emergence and cause basal rot of seedlings. It is generally accepted that composts suppress plant diseases, improve soil nutrient availability and stimulate plant growth. However, no reports have [...] been found on the simultaneous evaluation of vermicompost as plant growth promoter and suppressive to damping-off caused by R. solani on tomatoes. This research evaluated the suppressive effects of different concentrations of vermicompost against R. solani and the ability of vermicompost to promote tomato seedlings growth. The microbial composition of the substratum was explored. Thirty six microorganisms were isolated, 13 of which were antagonic to R.solani in vitro. The addition of 25 to 100% of vermicompost promoted seedlings growth and prevented damping-off caused by R. solani.

MC, Rivera; ER, Wright; MV, López; D, Garda; MY, Barragué.

68

Diversidad genética de aislados de Rhizoctonia solani (Kuhn) de chile en México / Genetic diversity of Rhizoctonia solani isolates (Kuhn) from pepper in Mexico  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Una de las principales limitantes para la producción de chile son los hongos patógenos causantes de la enfermedad conocida como "marchitez del chile" o "secadera". Esta enfermedad puede ser devastadora cuando las condiciones climáticas son favorables para el patógeno. A pesar de que se han intentado [...] diferentes medios de control (químicos y culturales) ninguno ha tenido éxito. Una alternativa para su control es producir germoplasma resistente, sin embargo para poder establecer un programa de mejoramiento efectivo es necesario conocer la distribución y diversidad genética de los patógenos involucrados, particularmente de Rhizoctonia solani, que por su ubicuidad representa un peligro potencial en todas las zonas productoras. Por ello el objetivo fue caracterizar a R. solani en las zona Centro Norte de México y determinar su diversidad genética. Para cumplir con este objetivo se consideraron los estados de Chihuahua, Durango, Zacatecas, San Luis Potosí, Colima, Querétaro y Guanajuato donde en 2009 se colectaron plantas adultas de Chile con síntomas de marchitez, se aisló al hongo y se encontró una incidencia del 33%, encontrándose tanto en tallo como en raíz. Las células miceliales fueron multinucleadas, características de las cepas patogénicas. Las pruebas de anastomosis demostaron la presencia en México de los grupos GA4, GA-2.1, GA-IIB, GA-2IV, GA7, GA11, GA12 y GA13. La diversidad genética de este hongo fue muy alta, de tal manera que las relaciones demostradas por la construcción de dendrogramas no muestran tendencias homogéneas pues los principales grupos formados contienen elementos de todos los estados. Abstract in english One of the major constraints for the production of pepper are pathogenic fungi causing diseases known as "pepper blight" or "damping off". This disease can be devastating when weather conditions are favorable for the pathogen. Although different means of control (chemical and cultural) have benn use [...] d but none has been successful. An alternative to control is to produce resistant germplasm, however in order to establish an effective breeding program is necessary to know the distribution and genetic diversity of the pathogens involved, particularly Rhizoctonia solani, which by its ubiquity represents a potential danger in all producing areas. Thus, the objective was to characterize R. solani in North Central area from Mexico and determine its genetic diversity. To achieve with this goal are considered the states of Chihuahua, Durango, Zacatecas, San Luis Potosi, Colima, Queretaro and Guanajuato where in 2009 were collected adult plants of pepper with pepper blight symptoms, the fungus was isolated and found an incidence of 33%, finding it in both stem and root. Mycelial cells were multinucleated, a characteristic from pathogenic strains. The anastomosis testing showed that in Mexico are present the groups GA4, GA-2. 1, GA-IIB, GA-2IV, GA7, GA11, GA12 and GA13. The genetic diversity of this fungus was very high, so that the relationships demonstrated by the construction of dendrogram show no homogeneous trends so as the main groups formed contain elements of all states.

Víctor, Montero-Tavera; Brenda Zulema, Guerrero-Aguilar; José Luis, Anaya-López; Talina Olivia, Martínez-Martínez; Lorenzo, Guevara-Olvera; Mario Martín, González-Chavira.

1043-10-01

69

Diversidad genética de aislados de Rhizoctonia solani (Kuhn) de chile en México / Genetic diversity of Rhizoctonia solani isolates (Kuhn) from pepper in Mexico  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Una de las principales limitantes para la producción de chile son los hongos patógenos causantes de la enfermedad conocida como "marchitez del chile" o "secadera". Esta enfermedad puede ser devastadora cuando las condiciones climáticas son favorables para el patógeno. A pesar de que se han intentado [...] diferentes medios de control (químicos y culturales) ninguno ha tenido éxito. Una alternativa para su control es producir germoplasma resistente, sin embargo para poder establecer un programa de mejoramiento efectivo es necesario conocer la distribución y diversidad genética de los patógenos involucrados, particularmente de Rhizoctonia solani, que por su ubicuidad representa un peligro potencial en todas las zonas productoras. Por ello el objetivo fue caracterizar a R. solani en las zona Centro Norte de México y determinar su diversidad genética. Para cumplir con este objetivo se consideraron los estados de Chihuahua, Durango, Zacatecas, San Luis Potosí, Colima, Querétaro y Guanajuato donde en 2009 se colectaron plantas adultas de Chile con síntomas de marchitez, se aisló al hongo y se encontró una incidencia del 33%, encontrándose tanto en tallo como en raíz. Las células miceliales fueron multinucleadas, características de las cepas patogénicas. Las pruebas de anastomosis demostaron la presencia en México de los grupos GA4, GA-2.1, GA-IIB, GA-2IV, GA7, GA11, GA12 y GA13. La diversidad genética de este hongo fue muy alta, de tal manera que las relaciones demostradas por la construcción de dendrogramas no muestran tendencias homogéneas pues los principales grupos formados contienen elementos de todos los estados. Abstract in english One of the major constraints for the production of pepper are pathogenic fungi causing diseases known as "pepper blight" or "damping off". This disease can be devastating when weather conditions are favorable for the pathogen. Although different means of control (chemical and cultural) have benn use [...] d but none has been successful. An alternative to control is to produce resistant germplasm, however in order to establish an effective breeding program is necessary to know the distribution and genetic diversity of the pathogens involved, particularly Rhizoctonia solani, which by its ubiquity represents a potential danger in all producing areas. Thus, the objective was to characterize R. solani in North Central area from Mexico and determine its genetic diversity. To achieve with this goal are considered the states of Chihuahua, Durango, Zacatecas, San Luis Potosi, Colima, Queretaro and Guanajuato where in 2009 were collected adult plants of pepper with pepper blight symptoms, the fungus was isolated and found an incidence of 33%, finding it in both stem and root. Mycelial cells were multinucleated, a characteristic from pathogenic strains. The anastomosis testing showed that in Mexico are present the groups GA4, GA-2. 1, GA-IIB, GA-2IV, GA7, GA11, GA12 and GA13. The genetic diversity of this fungus was very high, so that the relationships demonstrated by the construction of dendrogram show no homogeneous trends so as the main groups formed contain elements of all states.

Víctor, Montero-Tavera; Brenda Zulema, Guerrero-Aguilar; José Luis, Anaya-López; Talina Olivia, Martínez-Martínez; Lorenzo, Guevara-Olvera; Mario Martín, González-Chavira.

70

Chitosan-cinnamon beads enhance suppressive activity against Rhizoctonia solani and Meloidogyne incognita in vitro.  

Science.gov (United States)

A novel chitosan-cinnamon bead carrier was prepared in this study. Chitosan was mixed with cinnamon powder (CP) and cinnamon extract (CE) to obtain chitosan-cinnamon powder (CCP) beads and chitosan-cinnamon extracted (CCE) beads, respectively. The potential antifungal and nematicidal activities of CCP and CCE were investigated against Rhizoctonia solani and Meloidogyne incognita in vitro. Relative antifungal activity of the CCP (5% CP) bead-treated R. solani was 30.9 and 23.9% after 1 and 2 day incubations, respectively. Relative antifungal activity of the CCE (0.5% CE) bead-treated R. solani was 4.3, 3.0 and 4.2% after 1, 2 and 3 days of incubation. Inhibition of hatch by CCP beads with CP of 5% was 78.8%. Inhibition of hatch by CCE beads with CE of 0.5% was 82.0%. J2 mortality following the CCP (5% CP) and CCE (0.5% CE) bead treatments was 85.0 and 95.8%, respectively against M. incognita after 48 h incubations. PMID:24417978

Seo, Dong-Jun; Nguyen, Dang-Minh-Chanh; Park, Ro-Dong; Jung, Woo-Jin

2014-01-01

71

Genetic Variability in Rhizoctonia solani Isolated from Vitis vinifera Based on Amplified Fragment Length Polymorphism  

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Full Text Available Problem statement: Rhizoctonia solani is a potential grapevine pathogen. In order to develop effective methods of control, it is necessary to document its genetic diversity. Approach: The objective of this study was to analyze the genetic variability of R. solani isolated from the rhizosphere of ungrafted V. vinifera var. perlette seedless planted in Sonora, Mexico using Amplified Fragment Length Polymorphism (AFLP. Results: In the selective amplification using eight primer combinations we obtained a total of 446 AFLP markers with a 100% polymorphism. Out of 41 isolates, 36 different AFLP patterns were observed and five were replicates of the same pattern. The dendrogram shows inter- and intrapopulation similarity indexes of 0.26, 0.98 and 0.31, 0.98, respectively. Six groups emerged from the principal components analysis, five of which were clearly defined, while the other one was spread out. Conclusion: We conclude that R. solani growing in Sonoran vineyards shows a high degree of genetic variability, even under similar environmental conditions.

Amparo Meza-Moller

2011-01-01

72

High levels of gene flow and heterozygote excess characterize Rhizoctonia solani AG-1 IA (Thanatephorus cucumeris) from Texas.  

Science.gov (United States)

To date, much of the genetics of the basidiomycete Thanatephorus cucumeris (anamorph = Rhizoctonia solani) remains unknown. Here, we present a population genetics study using codominant markers to augment laboratory analyses. Seven single-copy nuclear RFLP markers were used to examine 182 isolates of Rhizoctonia solani AG-1 IA collected from six commercial rice fields in Texas. Thirty-six multilocus RFLP genotypes were identified. Population subdivision analyses indicated a high degree of gene flow/migration between the six geographic populations. Tests for Hardy-Weinberg equilibrium (HWE) among the 36 multilocus RFLP genotypes revealed that four of the seven loci did not significantly differ from HWE. Subsequent analysis demonstrated that departures from HWE at the three remaining loci were due to an excess of heterozygotes. Data presented here suggest that R. solani AG-1 IA is actively outbreeding (heterothallic). Possible explanations for heterozygote excess, which was observed at all seven RFLP loci, are discussed. PMID:10669581

Rosewich, U L; Pettway, R E; McDonald, B A; Kistler, H C

1999-12-01

73

Diversidade genética de isolados de Rhizoctonia solani coletados em feijão-caupi no Estado de Roraima / Genetic diversity of Rhizoctonia solani isolates collected from Cowpea in the State of Roraima  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O feijão-caupi (Vigna unguiculata) é uma das principais fontes de proteína para a população de baixa renda, principalmente nas Regiões Norte e Nordeste do Brasil. Esta leguminosa é suscetível a várias doenças incluindo a mela ou murcha-da-teia-micélica, cujo agente causal é o fungo Rhizoctonia solan [...] i (teleomorfo: Thanatephorus cucumeris). Embora Rhizoctonia solani seja um agente causal de doença muito importante, no Brasil inexiste qualquer informação sobre as características de seus isolados associados ao feijão-caupi. O objetivo do presente estudo foi avaliar, utilizando-se das técnicas Random Amplified Polymorphic DNA (RAPD) e RFLP-ITS (Internal Transcribed Spacer), a diversidade genética de isolados de R. solani coletados de plantas de feijão-caupi oriundas da região de cerrado e de mata do Estado de Roraima. Pelos resultados obtidos pode-se concluir que existe diversidade genética em R.. solani coletada de feijão-caupi e que os dois métodos moleculares utilizados foram eficientes em avaliar a divergência genética deste patógeno. Abstract in english Cowpea (Vigna unguiculata) is one of the most important sources of protein for people with low incomes in Northern and Northeastern Brazil. Cowpea is susceptible to several diseases, including web blight caused by the fungus Rhizoctonia solani (teleomorph Thanatephorus cucumeris). Although R. solani [...] is a very important disease agent, in Brazil there is no information on isolate characteristics when this fungus is associated with cowpea. The objective of this study was to evaluate, using Random Amplified Polymorphic DNA (RAPD) and RFLP-ITS (Internal Transcribed Spacer) techniques, the genetic diversity of R. solani isolates collected in the State of Roraima from cowpea cultivated under 'savannah' and 'forest' ecosystems. From the results it was possible to demonstrate genetic diversity among R. solani isolates and to prove that both molecular techniques used were efficient in evaluating it.

Aloísio, Sartorato; Kátia L., Nechet; Bernardo A., Halfeld-Vieira.

2006-06-01

74

Diversidade genética de isolados de Rhizoctonia solani coletados em feijão-caupi no Estado de Roraima / Genetic diversity of Rhizoctonia solani isolates collected from Cowpea in the State of Roraima  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O feijão-caupi (Vigna unguiculata) é uma das principais fontes de proteína para a população de baixa renda, principalmente nas Regiões Norte e Nordeste do Brasil. Esta leguminosa é suscetível a várias doenças incluindo a mela ou murcha-da-teia-micélica, cujo agente causal é o fungo Rhizoctonia solan [...] i (teleomorfo: Thanatephorus cucumeris). Embora Rhizoctonia solani seja um agente causal de doença muito importante, no Brasil inexiste qualquer informação sobre as características de seus isolados associados ao feijão-caupi. O objetivo do presente estudo foi avaliar, utilizando-se das técnicas Random Amplified Polymorphic DNA (RAPD) e RFLP-ITS (Internal Transcribed Spacer), a diversidade genética de isolados de R. solani coletados de plantas de feijão-caupi oriundas da região de cerrado e de mata do Estado de Roraima. Pelos resultados obtidos pode-se concluir que existe diversidade genética em R.. solani coletada de feijão-caupi e que os dois métodos moleculares utilizados foram eficientes em avaliar a divergência genética deste patógeno. Abstract in english Cowpea (Vigna unguiculata) is one of the most important sources of protein for people with low incomes in Northern and Northeastern Brazil. Cowpea is susceptible to several diseases, including web blight caused by the fungus Rhizoctonia solani (teleomorph Thanatephorus cucumeris). Although R. solani [...] is a very important disease agent, in Brazil there is no information on isolate characteristics when this fungus is associated with cowpea. The objective of this study was to evaluate, using Random Amplified Polymorphic DNA (RAPD) and RFLP-ITS (Internal Transcribed Spacer) techniques, the genetic diversity of R. solani isolates collected in the State of Roraima from cowpea cultivated under 'savannah' and 'forest' ecosystems. From the results it was possible to demonstrate genetic diversity among R. solani isolates and to prove that both molecular techniques used were efficient in evaluating it.

Aloísio, Sartorato; Kátia L., Nechet; Bernardo A., Halfeld-Vieira.

75

Investigating the roles of MicroRNAs in biotic stress response induced by Rhizoctonia solani in rice  

Science.gov (United States)

Sheath blight disease, caused by Rhizoctonia solani 1802/KB was screened on two rice varieties, Oryza sativaindica cultivar MR219 and Oryza sativa indica cultivar UKMRC9. The disease symptom was severe in MR219 compared to UKMRC9. Total RNA from R. solani 1802/KB, infected rice leaves of MR219 and infected rice leaves of UKMRC9 were extracted using TRIzol reagent, purified and sent for small RNA sequencing. Three miRNA libraries were generated and analyzed. The libraries generated 65 805, 78 512 and 81 325 known miRNAs respectively. The structure of miRNA of these samples was predicted. The up-regulated and down-regulated of miRNAs target gene prediction and its target functions were discovered and were mainly related to the growth and development of metabolism, protein transport, transcriptional regulation, stress response, and hormone signaling and electron transfer. Sheath blight-induced differential expression of known miRNAs tends to targetMYB transcription factor, F-box proteins, NBS-LRR, leucine-rich repeat receptor protein kinases and zinc finger proteins. Detecting new miRNAs and measuring the expression profiles of known miRNAs is an important tasks required for a better understanding of various biological conditions. Therefore, further analysis using Gene Ontology Slim will be conducted to deduce some biological information from the datasets obtained.

Syuhada, O. Nurfarahana; Kalaivani, N.

2014-09-01

76

Genetic diversity of Rhizoctonia solani AG-3 from potato and tobacco in North Carolina.  

Science.gov (United States)

Anastomosis group 3 (AG-3) of Rhizoctonia solani (teleomorph = Thanatephorus cucumeris) is frequently associated with diseases of potato (AG-3 PT) and tobacco (AG-3 TB). Although isolates of R. solani AG-3 from these two Solanaceous hosts are somatically related based on anastomosis reaction and taxonomically related based on fatty acid, isozyme and DNA characters, considerable differences are evident in their biology, ecology, and epidemiology. However, genetic diversity among field populations of R. solani AG-3 PT and TB has not been documented. In this study, the genetic diversity of field populations of R. solani AG-3 PT and AG-3 TB in North Carolina was examined using somatic compatibility and amplified fragment length polymorphism (AFLP) criteria. A sample of 32 isolates from potato and 36 isolates from tobacco were paired in all possible combinations on PDA plus activated charcoal and examined for their resulting somatic interactions. Twenty-eight and eight distinct somatic compatibility groups (SCG) were identified in the AG-3 PT and AG-3 TB samples, respectively. AFLP analyses indicated that each of the 32 AG-3 PT isolates had a distinct AFLP phenotype, whereas 28 AFLP phenotypes were found among the 36 isolates of AG-3 TB. None of the AG-3 PT isolates were somatically compatible or shared a common AFLP phenotype with any AG-3 TB isolate. Clones (i.e., cases where two or more isolates were somatically compatible and shared the same AFLP phenotype) were identified only in the AG-3 TB population. Four clones from tobacco represented 22% of the total population. All eight SCG from tobacco were associated with more than one AFLP phenotype. Compatible somatic interactions between AG-3 PT isolates occurred only between certain isolates from the same field (two isolates in each of four different fields), and when this occurred AFLP phenotypes were similar but not identical. PMID:21156515

Ceresini, Paulo C; Shew, H David; Vilgalys, Rytas J; Cubeta, Marc A

2002-01-01

77

Randomly Amplified Polymorphic DNA of Trichoderma isolates and antagonism against Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese A técnica de RAPD (Random Amplified Polymorphic DNA) foi utilizada para examinar a variabilidade genética em quatorze isolados de Trichoderma além de sua capacidade de antagonizar o fungo fitopatogênico Rhizoctonia solani usando pareamento in vitro, e a possível relação entre perfís de RAPD e agress [...] ividade dos isolados de Trichoderma a R. solani. Foram selecionados sete primers para os ensaios de RAPD, os quais produziram 197 bandas. Os dados foram introduzidos no programa de computador NTSYS (Numerical Taxonomy System, Applied Biostatistics)na forma de uma matrix binária, sendo construída uma matriz de similaridade utilizando-se o coeficiente de similaridade de DICE (SD) e baseado nos valores SD, pelo método de agrupamento UPGMA um dendrograma. Observou-se que o grau de similaridade das amostras que apresentaram melhor desempenho antagônico foi bastante baixo, em torno de 40%. Os resultados demonstraram que a variabilidade entre os isolados de Trichoderma é muito alta. Aparentemente não foi demonstrada nenhuma relação entre o perfil de RAPD obtido e o nível de antagonismo dos isolados de Trichoderma nem agrupamento em função da origem dos isolados ou substrato. Abstract in english Random Amplified Polymorphic DNA (RAPD) procedure was used to examine the genetic variability among fourteen isolates of Trichoderma and their ability to antagonize Rhizoctonia solani using a dual-culture assay for correlation among RAPD products and their hardness to R. solani. Seven oligodeoxynucl [...] eotide primers were selected for the RAPD assays which resulted in 197 bands for 14 isolates of Trichoderma. The data were entered into a binary matrix and a similarity matrix was constructed using DICE similarity (SD) index. A UPGMA cluster based on SD values was generated using NTSYS (Numerical Taxonomy System, Applied Biostatistics) computer program. A mean coefficient of similarity obtained for pairwise comparisons among the most antagonics isolates was around 40%. The results presented here showed that the variability among the isolates of Trichoderma was very high. No relationship was found between the polymorphism showed by the isolates and their hardness, origin and substrata.

Larissa Brandão, Góes; Ana Bolena Lima da, Costa; Laurineide Lopes de Carvalho, Freire; Neiva Tinti de, Oliveira.

2002-06-01

78

Identifikasi dan Kuantifikasi Metabolit Bakteri Pelarut Fosfat dan Pengaruhnya terhadap Aktivitas Rhizoctonia solani pada Tanaman Kedelai  

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Full Text Available Phosphate solubilizing bacteria (PSB metabolites are organic acids, phosphomonoesterase enzyme (alkaline phosphatase and antibiotic, which is able to dissolve insoluble phosphate. Phosphate solubilizing bacteria used in this study was expected to suppress Rhizoctonia solani attacks. This experiment was aimed at (1 identifiying and quantifying PSB metabolites, and (2 examining their capability as biocontrol agent for Rhizoctonia solani in vitro and hydroponics soybean. This study was conducted in three stages. The first stage of this study was culturing two PSB isolates (Pseudomonas putida 27.4B and Pseudomonas diminuta in the Pikovskaya medium to analyze their metabolites. The second and third stage of this study was testing the antagonist of two bacteria to suppressed R. solani activity, which was conducted in vitro, and in hydroponics medium soybean as indicator plant. The results showed that P. putida 27.4B and P. diminuta produced organic acids i.e.: citrate, formic, succinic, acetic, propionate, butyrate, and oxalate. The totals of organic acids from each bacterium were 70,3 mg.kg-1 and 61,9 mg.kg-1. Production of alkaline phosphatase enzyme in Pikovskaya medium of P. Putida 27.4B was 11,71 ìg pNP .mL-1.h-1 and P. diminuta was 24,04 ìg pNP.mL-1.h-1. Concentration of this enzyme in soil medium was higher than that in Pikovskaya medium with 26,27 ìg pNP.g-1.h-1 and 39,03 ìg pNP.g-1.h-1 respectively. This study also showed that total concentration of antibiotics (tetracycline, oxitetracycline and penicillin produced by the PSB, were 3,2 ìg.mL-1 (P. putida 27.4B and 10,96 ìg.m1-1 (P. diminuta, respectively. The results from second stage of this study showed that by using in vitro, the reduced growth of R. solani was observed 58,35% with P. putida 27.4B and 41,96% with P. diminuta. In addition, inoculations of PSB in hydroponics medium reduced the fungal pathogenesis from 10,71% to 21,42% of pre and post emergence damping-off. Visually, the symptom of pathogen attack appeared within the period of 2 untill 14 days after infection.

Tri Candra Setiawati

2008-09-01

79

Randomly Amplified Polymorphic DNA of Trichoderma isolates and antagonism against Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A técnica de RAPD (Random Amplified Polymorphic DNA) foi utilizada para examinar a variabilidade genética em quatorze isolados de Trichoderma além de sua capacidade de antagonizar o fungo fitopatogênico Rhizoctonia solani usando pareamento in vitro, e a possível relação entre perfís de RAPD e agress [...] ividade dos isolados de Trichoderma a R. solani. Foram selecionados sete primers para os ensaios de RAPD, os quais produziram 197 bandas. Os dados foram introduzidos no programa de computador NTSYS (Numerical Taxonomy System, Applied Biostatistics)na forma de uma matrix binária, sendo construída uma matriz de similaridade utilizando-se o coeficiente de similaridade de DICE (SD) e baseado nos valores SD, pelo método de agrupamento UPGMA um dendrograma. Observou-se que o grau de similaridade das amostras que apresentaram melhor desempenho antagônico foi bastante baixo, em torno de 40%. Os resultados demonstraram que a variabilidade entre os isolados de Trichoderma é muito alta. Aparentemente não foi demonstrada nenhuma relação entre o perfil de RAPD obtido e o nível de antagonismo dos isolados de Trichoderma nem agrupamento em função da origem dos isolados ou substrato. Abstract in english Random Amplified Polymorphic DNA (RAPD) procedure was used to examine the genetic variability among fourteen isolates of Trichoderma and their ability to antagonize Rhizoctonia solani using a dual-culture assay for correlation among RAPD products and their hardness to R. solani. Seven oligodeoxynucl [...] eotide primers were selected for the RAPD assays which resulted in 197 bands for 14 isolates of Trichoderma. The data were entered into a binary matrix and a similarity matrix was constructed using DICE similarity (SD) index. A UPGMA cluster based on SD values was generated using NTSYS (Numerical Taxonomy System, Applied Biostatistics) computer program. A mean coefficient of similarity obtained for pairwise comparisons among the most antagonics isolates was around 40%. The results presented here showed that the variability among the isolates of Trichoderma was very high. No relationship was found between the polymorphism showed by the isolates and their hardness, origin and substrata.

Larissa Brandão, Góes; Ana Bolena Lima da, Costa; Laurineide Lopes de Carvalho, Freire; Neiva Tinti de, Oliveira.

80

Identification and functional analysis of AG1-IA specific genes of Rhizoctonia solani.  

Science.gov (United States)

Rhizoctonia solani is an important necrotrophic fungal pathogen which causes disease on diverse plant species. It has been classified into 14 genetically distinct anastomosis groups (AGs), however, very little is known about their genomic diversity. AG1-IA causes sheath blight disease in rice and controlling this disease remains a challenge for sustainable rice cultivation. Recently the draft genome sequences of AG1-IA (rice isolate) and AG1-IB (lettuce isolate) had become publicly available. In this study, using comparative genomics, we report identification of 3,942 R. solani genes that are uniquely present in AG1-IA. Many of these genes encode important biological, molecular functions and exhibit dynamic expression during in-planta growth of the pathogen in rice. Based upon sequence similarity with genes that are required for plant and human/zoonotic diseases, we identified several putative virulence/pathogenicity determinants amongst AG1-IA specific genes. While studying the expression of 19 randomly selected genes, we identified three genes highly up-regulated during in-planta growth. The detailed in silico characterization of these genes and extent of their up-regulation in different rice genotypes, having variable degree of disease susceptibility, suggests their importance in rice-Rhizoctonia interactions. In summary, the present study reports identification, functional characterization of AG1-IA specific genes and predicts important virulence determinants that might enable the pathogen to grow inside hostile plant environment. Further characterization of these genes would shed useful insights about the pathogenicity mechanism of AG1-IA on rice. PMID:25070039

Ghosh, Srayan; Gupta, Santosh Kumar; Jha, Gopaljee

2014-11-01

 
 
 
 
81

Molecular Characterization and Screening for Sheath Blight Resistance Using Malaysian Isolates of Rhizoctonia solani.  

Science.gov (United States)

Two field isolates of Rhizoctonia solani were isolated from infected paddy plants in Malaysia. These isolates were verified via ITS-rDNA analysis that yielded ~720?bp products of the ITS1-5.8S-ITS4 region, respectively. The sequenced products showed insertion and substitution incidences which may result in strain diversity and possible variation in disease severity. These strains showed some regional and host-specific relatedness via Maximum Likelihood and further phylogenetic analysis via Maximum Parsimony showed that these strains were closely related to R. solani AG1-1A (with 99-100% identity). Subsequent to strain verification and analysis, these isolates were used in the screening of twenty rice varieties for tolerance or resistance to sheath blight via mycelial plug method where both isolates (1801 and 1802) showed resistance or moderate resistance to Teqing, TETEP, and Jasmine 85. Isolate 1802 was more virulent based on the disease severity index values. This study also showed that the mycelial plug techniques were efficient in providing uniform inoculum and humidity for screening. In addition this study shows that the disease severity index is a better mode of scoring for resistance compared to lesion length. These findings will provide a solid basis for our future breeding and screening activities at the institution. PMID:25258710

Nadarajah, Kalaivani; Omar, Nurfarahana Syuhada; Rosli, Marhamah Md; Shin Tze, Ong

2014-01-01

82

Mechanism for mercury tolerance in fungi. [Aspergillus niger; Rhizoctonia solani; Pythium ultimum  

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Aspergillus niger was protected from mercury (Hg) poisoning by sulfhydryl (SH) compounds (glutathione and cysteine) in culture experiments, whereas Rhizoctonia solani and Pythium ultimum were not protected. Two- to 30-day-old mycelium of A. niger was found to be more tolerant to Hg than either younger or older mycelia. Mycelia of the other fungi were sensitive regardless of age. Mercury tolerance of A. niger mycelium was altered when sulfur nutrition was modified; it was greater after growth on a substrate containing reduced sulfur than after growth on one containing sulfate. The Hg tolerance of A. niger mycelium appears to be due to a pool of intracellular SH that is free of protein and that protects enzyme systems by forming complexes with Hg as it is taken up by the thallus. Potato-dextrose broth-grown mats of A. niger contained about 100 ..mu..g of SH/g of dry mycelia after 36 hr and after 5 days. R.. solani had about 9 ..mu..g of SH/g of mycelia after 5 days; a measurable amount was not recovered from P. ultimum. 20 references, 1 figure, 2 tables.

Ashworth, L.J. Jr.; Amin, J.V.

1964-01-01

83

Proteomic response of Rhizoctonia solani GD118 suppressed by Paenibacillus kribbensis PS04.  

Science.gov (United States)

Rice sheath blight, caused by Rhizoctonia solani, is considered a worldwide destructive rice disease and leads to considerable yield losses. A bio-control agent, Paenibacillus kribbensis PS04, was screened to resist against the pathogen. The inhibitory effects were investigated (>80 %) by the growth of the hyphae. Microscopic observation of the hypha structure manifested that the morphology of the pathogenic mycelium was strongly affected by P. kribbensis PS04. To explore essentially inhibitory mechanisms, proteomic approach was adopted to identify differentially expressed proteins from R. solani GD118 in response to P. kribbensis PS04 using two-dimensional gel electrophoresis. Protein profiling was used to identify 13 differential proteins: 10 proteins were found to be down-regulated while 3 proteins were up-regulated. These proteins were involved in material and energy metabolism, antioxidant activity, protein folding and degradation, and cytoskeleton regulation. Among them, material and energy metabolism was differentially regulated by P. kribbensis PS04. Protein expression was separately inhibited by the bio-control agent in oxidation resistance, protein folding and degradation, and cytoskeleton regulation. Proteome changes of the mycelium assist in understanding how the pathogen was directly suppressed by P. kribbensis PS04. PMID:25164959

Wang, Liuqing; Liu, Mei; Liao, Meide

2014-12-01

84

Isolation and characterization of siderophore producing antagonistic rhizobacteria against Rhizoctonia solani.  

Science.gov (United States)

Plant protection through siderophore producing rhizobacteria (SPR) has emerged as a sustainable approach for crop health management. In present study, 220 bacteria isolated from tomato rhizosphere were screened for in vitro antagonistic activity against Rhizoctonia solani AG-4. Nine potent antagonistic strains viz., Alcaligenes sp. (MUN1, MB21, and MPF37), Enterobacter sp. (MPM1), Pseudomonas sp. (M10A and MB65), P. aeruginosa (MPF14 and MB123) and P. fluorescens (MPF47) were identified on the basis of physiological characters and 16S rDNA sequencing. These strains were able to produce hydrolytic enzymes, hydrogen cyanide, indole acetic acid, although, only few strains were able to solubilize phosphate. Two strains (MB123 and MPF47) showed significant disease reduction in glasshouse conditions were further evaluated under field conditions using three different application methods. Application of P. fluorescens (MPF47) in nursery as soil mix?+?seedling root treatments prior to transplantation resulted in significant disease reduction compared to control. Total chlorophyll and available iron were significantly higher in the MPF47 treated plants in contrast to infected control. In conclusion, siderophore producing bacteria MPF47 have strong biocontrol abilities and its application as soil mix?+?seedling root treatments provided strong shield to plant roots against R. solani and could be used for effective bio-management of pathogen. PMID:23686438

Solanki, Manoj Kumar; Singh, Rajesh Kumar; Srivastava, Supriya; Kumar, Sudheer; Kashyap, Prem Lal; Srivastava, Alok K; Arora, Dilip K

2014-06-01

85

Virulence and molecular characterization of Costa Rican isolates of Rhizoctonia solani from common bean  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Web blight is one of the main diseases that affects bean (Phaseolus vulgaris) cultivation. It infects diverse organs at any growth stage of the plant and can be present at different altitudes in a humid tropical climate. The causal agent of this disease is Thanatephorus cucumeris in its sexual stage [...] and Rhizoctonia solani in the anamorph. The objective of this investigation was to characterize molecular isolates of R. solani obtained from bean plants from diverse production regions in Costa Rica and determine their virulence. Fifty-one samples of symptomatic bean plants were collected using a global positioning system. Virulence was evaluated using the detached leaf technique. Isolates were identified using AG 1-IA, AG 1-IB, AG 1-IC, AG 1-ID, AG 2-2, AG 2-2IIIB, AG 2-2IV and AG 4 molecular markers. ITS sequences were obtained and analyzed with BLAST, aligned, and a phylogenetic tree was constructed. A high degree of virulence and genetic variability between isolates was identified and the anastomosis subgroups of isolates were independent of their geographical origin.

Floribeth, Mora-Umaña; Natalia, Barboza; Ricardo, Alvarado; Marcela, Vásquez; Graciela, Godoy-Lutz; James R., Steadman; Pilar, Ramírez.

86

Application of Fluorescent Pseudomonads in Biological Control of Rhizoctonia solani , Causal Agent of Colza  

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Full Text Available   Two hundred fifty seven bacterial isolates were collected from colza root and rhizosphere in Golestan, Mazandaran, Guilan and Tehran provinces. Antagonistic effect of bacterial isolates on Rhizoctonia solani, the causal agent of colza damping off, was studied using dual culture method. The results showed that, 60 isolates had the ability to inhibit the growth of R. solani on PDA medium. On the basis of the biochemical, physiological and morphological tests, isolates P1, P2 and P3 were identified as Pseudomonas fluorescens. Biocontrol mechanism studies showed that isolates produced antibiotics and volatile metabolites prevented the mycelial growth of the fungus. The isolates produced some of antimicrobial metabolites including hydrogen cyanide, protease and siderophore. Isolate P3 was more effective to inhibit the growth of the fungus in-vitro. The effect of isolates on disease reduction in comparison with control was significantly different. None of the isolates were able to prevent disease occurrence completely. Isolates applied as soil treatment had a significantly higher disease control as compared to seed treatment method. Isolate P3 had considerable effect on reduction disease in the greenhouse conditions. All isolates were capable of colonizing canola roots and so increased canola growth in free-causal agent conditions.

M. Javan Nikkhah

2008-01-01

87

Virulence and molecular characterization of Costa Rican isolates of Rhizoctonia solani from common bean  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Web blight is one of the main diseases that affects bean (Phaseolus vulgaris) cultivation. It infects diverse organs at any growth stage of the plant and can be present at different altitudes in a humid tropical climate. The causal agent of this disease is Thanatephorus cucumeris in its sexual stage [...] and Rhizoctonia solani in the anamorph. The objective of this investigation was to characterize molecular isolates of R. solani obtained from bean plants from diverse production regions in Costa Rica and determine their virulence. Fifty-one samples of symptomatic bean plants were collected using a global positioning system. Virulence was evaluated using the detached leaf technique. Isolates were identified using AG 1-IA, AG 1-IB, AG 1-IC, AG 1-ID, AG 2-2, AG 2-2IIIB, AG 2-2IV and AG 4 molecular markers. ITS sequences were obtained and analyzed with BLAST, aligned, and a phylogenetic tree was constructed. A high degree of virulence and genetic variability between isolates was identified and the anastomosis subgroups of isolates were independent of their geographical origin.

Floribeth, Mora-Umaña; Natalia, Barboza; Ricardo, Alvarado; Marcela, Vásquez; Graciela, Godoy-Lutz; James R., Steadman; Pilar, Ramírez.

2013-12-01

88

INDUCE SYSTEMIC RESISTANCE AGAINST BLACK SCARF DISEASE CAUSED BY Rhizoctonia solani IN POTATO (Solanum tuberosum  

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Full Text Available In present study influence of ?-aminobutyric acid, salicylic acid and hydrogenperoxide were tested to induced systemic resistance against black scarf disease caused by Rhizoctonia solani in potato. Results of the present study revealed that both salicylic acid and hydrogen peroxide treatments effectively reduced percentage severity of black scarf on potato tubers. This reduction was recorded 10.00 and 23.34% for salicylic acid at150 and 250 mg/L respectively, while these reduction were 6.67 and 3.37% respectively at both the concentration (150 and 250 mg/L of hydrogen peroxide. All the treated plants with BABA, salicylic acid and hydrogen peroxide were showed a significant increase in potato tuber yield as compared with check (R. solani only at150 and 250 mg/l, it was82.50, 137.5, 128.5, 128.7, 149.0 and 414.2 g for pathogen treatment. Treatment containing spraying of 250 mg/l Hydrogen peroxide showed the maximum improvement in fresh and dry weight, and potato tubers yield as compared with all treatments. Furthermore, plant characters results showed that treatment containing 150 mg/l BABA and H2O2 was significantly increase the content of chlorophyll type A and B as compared with check (R. solani only at (0.74, 1.07 and (0.71, 1.06 and (0.69, 1.00 µg/ml respectively, as well as total chlorophyll was significantly increased to same treatments at 1.82, 1.75 and 1.69 µg/ml respectively. Hydrogen peroxide 150 mg/L showed significantly increased peroxidase activity after 48 h from spray compared with pathogen treatment (R. solani only at 5.71 and 4.68 change the absorption respectively, While after 30 day of spray with chemicals inducer all treatments showed a significantly increased with peroxidaes activity compared with pathogen treatment (R. solani only and this improvement was 7.21, 5.91, 7.55, 6.37, 7.78, 8.19 and 5.18 respectively.

Oadi N Matny

2014-07-01

89

Comparison of different methods for total RNA extraction from sclerotia of Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Background Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) is one of the most important pathogens of rice (Oryza sativa L.) that causes severe yield losses in all rice-growing regions. Sclerotia, formed from the aggregation of hyphae, are important structures in the life cycles of R. solani [...] and contain a large quantity of polysaccharides, lipids, proteins and pigments. In order to extract high-quality total RNA from the sclerotia of R. solani, five methods, including E.Z.N.A.™ Fungal RNA Kit, sodium dodecyl sulfate (SDS)-sodium borate, SDS-polyvinylpyrrolidone (PVP), guanidinium thiocyanate (GTC) and modified Trizol, were compared in this study. Results The electrophoresis results showed that it failed to extract total RNA from the sclerotia using modified Trizol method, whereas it could extract total RNA from the sclerotia using other four methods. Further experiments confirmed that the total RNA extracted using SDS-sodium borate, SDS-PVP and E.Z.N.A.™ Fungal RNA Kit methods could be used for RT-PCR of the specific amplification of GAPDH gene fragments, and that extracted using GTC method did not fulfill the requirement for above-mentioned RT-PCR experiment. Conclusion It is concluded that SDS-sodium borate and SDS-PVP methods were the better ones for the extraction of high-quality total RNA that could be used for future gene cloning and expression studies, whereas E.Z.N.A.™ Fungal RNA Kit was not taken into consideration when deal with a large quantity of samples because it is expensive and relatively low yield.

Canwei, Shu; Si, Sun; Jieling, Chen; Jianyi, Chen; Erxun, Zhou.

2014-01-15

90

Occurrence of Banded Leaf and Sheath Blight of Maize in Jharkhand with Reference to Diversity in Rhizoctonia solani  

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Full Text Available Survey during kharif, 2005 and 2006 were carried out to record occurrence of disease and diversity in R. solani among the naturally occurring populations and revealed that banded leaf and sheathblight incited by Rhizoctonia solani, is show ing wide spread w ith the disease severity ranging from 30.30 to80.46 per cent and gaining the economic importance in the state of Jharkhand. Five isolates from five differentlocations showed variation in their morphological characters such as abundance of mycelium, colour andlocation, distribution, size and density of sclerotia etc. Pathogenicity revealed isolate Hc most aggressive whileisolate Jr least aggressive.

J. Akhtar

2009-10-01

91

Biological Control of Potato Isolate of Rhizoctonia solani by Streptomyces olivaceus Strain 115  

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This is the first report of antifungal activity of Iranian actinomycete isolates against Rhizoctonia solani Kuhn AG-3 (Teleomorph: Thanatephorus cucumeris [(Frank) Donk]). Biological control offers an environmentally friendly alternative to the use of antimicrobials for controlling plant diseases. A collection of about 200 actinomycete strains was screened for the ability to produce metabolites that inhibit R. solani growth in vitro. The Streptomyces ol...

Shahrokhi, S.; Shahidi Bonjar, G. H.; Saadoun, I.

2005-01-01

92

Effect of Certain Fungicides and Isolates of Antagonistic Fungi on Rhizoctonia solani, the Causal Agent of Rice Sheath Blight  

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Antagonistic fungi Trichoderma harzianum (T1, from bean fields in Ahwaz, T2, from rice fields in Rasht), T. viride (T3 from bean fields in Shahriar, T4 from the collection in Plant Pest and Disease Institute, Tehran), Gliocladium virens (from bean fields in Kamal Abad, Karaj) and some fungicides (Benomyl, Carbendazim, Carboxin-Thiram, edifenphos and Zineb) were used to control sheath blight of rice incited by Rhizoctonia solani in vitro and under greenhouse conditions. The experiment was carr...

Elahinia, S. A.; Pedramfar, H.; Niknejad Kazempour, M.

2003-01-01

93

Dried powders of velvetbean and pine bark added to soil reduce Rhizoctonia solani-induced disease on soybean / Pós secos de mucuna e casca de pinus adicionados ao solo reduzem a doença causada por Rhizoctonia solani em soja  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese As doenças em soja (Glycine max) causadas por Rhizoctonia solani são um sério problema ao redor do mundo. A incorporação ao solo de resíduos orgânicos é uma alternativa para o controle destas doenças. Neste estudo, benzaldeido e pós-secos de kudzu (Pueraria lobata), mucuna (Mucuna deeringiana) e cas [...] ca de pinus (Pinus spp.) foram usados com o objetivo de melhorar o crescimento de plantas de soja e de diminuir a doença causada por R. solani (AG-4). Benzaldehyde (0,1-0,4 mL/kg de solo) e mucuna (25-100 g/kg) reduziram significativamente (P Abstract in english Diseases induced by Rhizoctonia solani, like damping-off and root and stem rot on soybean (Glycine max), are a serious problem around the world. The addition of some organic material to soil is an alternative control for these diseases. In this study, benzaldehyde and dried powders of kudzu (Puerari [...] a lobata), velvetbean or mucuna (Mucuna deeringiana), and pine bark (Pinus spp.) were used in an attempt to improve soybean plant growth and to reduce the disease R. solani (AG-4) causes on soybean. Benzaldehyde (0.1-0.4 mL/kg of soil) and velvetbean (25-100 g/kg) significantly (P

Luiz E. B., Blum; Rodrígo, Rodríguez-Kábana.

2006-06-01

94

Genome sequencing and comparative genomics of the broad host-range pathogen Rhizoctonia solani AG8.  

Science.gov (United States)

Rhizoctonia solani is a soil-borne basidiomycete fungus with a necrotrophic lifestyle which is classified into fourteen reproductively incompatible anastomosis groups (AGs). One of these, AG8, is a devastating pathogen causing bare patch of cereals, brassicas and legumes. R. solani is a multinucleate heterokaryon containing significant heterozygosity within a single cell. This complexity posed significant challenges for the assembly of its genome. We present a high quality genome assembly of R. solani AG8 and a manually curated set of 13,964 genes supported by RNA-seq. The AG8 genome assembly used novel methods to produce a haploid representation of its heterokaryotic state. The whole-genomes of AG8, the rice pathogen AG1-IA and the potato pathogen AG3 were observed to be syntenic and co-linear. Genes and functions putatively relevant to pathogenicity were highlighted by comparing AG8 to known pathogenicity genes, orthology databases spanning 197 phytopathogenic taxa and AG1-IA. We also observed SNP-level "hypermutation" of CpG dinucleotides to TpG between AG8 nuclei, with similarities to repeat-induced point mutation (RIP). Interestingly, gene-coding regions were widely affected along with repetitive DNA, which has not been previously observed for RIP in mononuclear fungi of the Pezizomycotina. The rate of heterozygous SNP mutations within this single isolate of AG8 was observed to be higher than SNP mutation rates observed across populations of most fungal species compared. Comparative analyses were combined to predict biological processes relevant to AG8 and 308 proteins with effector-like characteristics, forming a valuable resource for further study of this pathosystem. Predicted effector-like proteins had elevated levels of non-synonymous point mutations relative to synonymous mutations (dN/dS), suggesting that they may be under diversifying selection pressures. In addition, the distant relationship to sequenced necrotrophs of the Ascomycota suggests the R. solani genome sequence may prove to be a useful resource in future comparative analysis of plant pathogens. PMID:24810276

Hane, James K; Anderson, Jonathan P; Williams, Angela H; Sperschneider, Jana; Singh, Karam B

2014-05-01

95

Resistência física de bainhas de plantas de arroz supridas com silício e infectadas por Rhizoctonia solani Physical resistance of leaf sheaths of rice plants supplied with silicon and infected by Rhizoctonia solani  

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Full Text Available Este trabalho objetivou associar a deposição de silício (Si nas bainhas de plantas de arroz ao aumento da resistência física à infecção por Rhizoctonia solani. Plantas das cultivares suscetíveis BR-Irga 409 e Labelle foram cultivadas em solução nutritiva contendo (+Si ou não (-Si Si. A concentração de Si nas bainhas das plantas supridas com Si e inoculadas com R. solani aumentou significativamente em relação às plantas não supridas com Si reduzindo o comprimento relativo da lesão às 96 horas após inoculação (hai. Houve diferença significativa entre os tratamentos -Si e +Si quanto à força necessária para uma agulha metálica atravessar as bainhas às 48 e 72 hai. A maior resistência física às 24 hai deve-se ao fato de que R. solani estava crescendo sobre o tecido sem destruí-lo, o que pôde ser comprovado pela ausência de sintomas. Após esse período, a resistência diminuiu devido ao rápido crescimento de R. solani. Entretanto, nas bainhas de plantas supridas com Si, a força necessária para a agulha penetrar foi maior às 48 e 72 hai. A resistência das bainhas de plantas supridas com Si à infecção por R. solani pode ser explicada, em parte, pela maior resistência física decorrente da deposição desse elemento.This study aimed to associate the silicon (Si deposition on sheaths of rice plants with an increase in physical resistance against infection by Rhizoctonia solani. Plants from the susceptible cultivars BR-Irga 409 and Labelle were grown in nutrient solution containing (+Si or not (-Si Si. Si concentration on sheaths of plants supplied with Si and inoculated with R. solani significantly increased compared to plants non-supplied with Si, reducing the relative lesion length at 96 hours after inoculation (hai. There were significant differences between -Si and +Si treatments for the force required of a metal needle to pass through the sheaths at 48 and 72 hai. The greater physical resistance at 24 hai was due to the fact that R. solani was growing on sheath tissue without destroying it, which could be proved by the absence of symptoms. After this period, the resistance decreased due to the rapid R. solani growth. However, on sheaths of plants supplied with Si, the force required for the needle to penetrate was higher at 48 and 72 hai. The sheath resistance of plants supplied with Si to infection by R. solani can be explained partly by the greater physical resistance due to Si deposition.

Daniel Augusto Schurt

2012-08-01

96

Resistência física de bainhas de plantas de arroz supridas com silício e infectadas por Rhizoctonia solani / Physical resistance of leaf sheaths of rice plants supplied with silicon and infected by Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho objetivou associar a deposição de silício (Si) nas bainhas de plantas de arroz ao aumento da resistência física à infecção por Rhizoctonia solani. Plantas das cultivares suscetíveis BR-Irga 409 e Labelle foram cultivadas em solução nutritiva contendo (+Si) ou não (-Si) Si. A concentraç [...] ão de Si nas bainhas das plantas supridas com Si e inoculadas com R. solani aumentou significativamente em relação às plantas não supridas com Si reduzindo o comprimento relativo da lesão às 96 horas após inoculação (hai). Houve diferença significativa entre os tratamentos -Si e +Si quanto à força necessária para uma agulha metálica atravessar as bainhas às 48 e 72 hai. A maior resistência física às 24 hai deve-se ao fato de que R. solani estava crescendo sobre o tecido sem destruí-lo, o que pôde ser comprovado pela ausência de sintomas. Após esse período, a resistência diminuiu devido ao rápido crescimento de R. solani. Entretanto, nas bainhas de plantas supridas com Si, a força necessária para a agulha penetrar foi maior às 48 e 72 hai. A resistência das bainhas de plantas supridas com Si à infecção por R. solani pode ser explicada, em parte, pela maior resistência física decorrente da deposição desse elemento. Abstract in english This study aimed to associate the silicon (Si) deposition on sheaths of rice plants with an increase in physical resistance against infection by Rhizoctonia solani. Plants from the susceptible cultivars BR-Irga 409 and Labelle were grown in nutrient solution containing (+Si) or not (-Si) Si. Si conc [...] entration on sheaths of plants supplied with Si and inoculated with R. solani significantly increased compared to plants non-supplied with Si, reducing the relative lesion length at 96 hours after inoculation (hai). There were significant differences between -Si and +Si treatments for the force required of a metal needle to pass through the sheaths at 48 and 72 hai. The greater physical resistance at 24 hai was due to the fact that R. solani was growing on sheath tissue without destroying it, which could be proved by the absence of symptoms. After this period, the resistance decreased due to the rapid R. solani growth. However, on sheaths of plants supplied with Si, the force required for the needle to penetrate was higher at 48 and 72 hai. The sheath resistance of plants supplied with Si to infection by R. solani can be explained partly by the greater physical resistance due to Si deposition.

Daniel Augusto, Schurt; Fabrício Ávila, Rodrigues; Ricardo Dutra, Reis; Wiler Ribas, Moreira; Naiara Fernandes Abreu, Souza; Washington Azevedo, Silva.

97

Resistência física de bainhas de plantas de arroz supridas com silício e infectadas por Rhizoctonia solani / Physical resistance of leaf sheaths of rice plants supplied with silicon and infected by Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho objetivou associar a deposição de silício (Si) nas bainhas de plantas de arroz ao aumento da resistência física à infecção por Rhizoctonia solani. Plantas das cultivares suscetíveis BR-Irga 409 e Labelle foram cultivadas em solução nutritiva contendo (+Si) ou não (-Si) Si. A concentraç [...] ão de Si nas bainhas das plantas supridas com Si e inoculadas com R. solani aumentou significativamente em relação às plantas não supridas com Si reduzindo o comprimento relativo da lesão às 96 horas após inoculação (hai). Houve diferença significativa entre os tratamentos -Si e +Si quanto à força necessária para uma agulha metálica atravessar as bainhas às 48 e 72 hai. A maior resistência física às 24 hai deve-se ao fato de que R. solani estava crescendo sobre o tecido sem destruí-lo, o que pôde ser comprovado pela ausência de sintomas. Após esse período, a resistência diminuiu devido ao rápido crescimento de R. solani. Entretanto, nas bainhas de plantas supridas com Si, a força necessária para a agulha penetrar foi maior às 48 e 72 hai. A resistência das bainhas de plantas supridas com Si à infecção por R. solani pode ser explicada, em parte, pela maior resistência física decorrente da deposição desse elemento. Abstract in english This study aimed to associate the silicon (Si) deposition on sheaths of rice plants with an increase in physical resistance against infection by Rhizoctonia solani. Plants from the susceptible cultivars BR-Irga 409 and Labelle were grown in nutrient solution containing (+Si) or not (-Si) Si. Si conc [...] entration on sheaths of plants supplied with Si and inoculated with R. solani significantly increased compared to plants non-supplied with Si, reducing the relative lesion length at 96 hours after inoculation (hai). There were significant differences between -Si and +Si treatments for the force required of a metal needle to pass through the sheaths at 48 and 72 hai. The greater physical resistance at 24 hai was due to the fact that R. solani was growing on sheath tissue without destroying it, which could be proved by the absence of symptoms. After this period, the resistance decreased due to the rapid R. solani growth. However, on sheaths of plants supplied with Si, the force required for the needle to penetrate was higher at 48 and 72 hai. The sheath resistance of plants supplied with Si to infection by R. solani can be explained partly by the greater physical resistance due to Si deposition.

Daniel Augusto, Schurt; Fabrício Ávila, Rodrigues; Ricardo Dutra, Reis; Wiler Ribas, Moreira; Naiara Fernandes Abreu, Souza; Washington Azevedo, Silva.

2012-08-01

98

A One-Step, Immunochromatographic Lateral Flow Device Specific to Rhizoctonia solani and Certain Related Species, and Its Use to Detect and Quantify R. solani in Soil.  

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ABSTRACT A murine hybridoma cell line GD2 secreting an immunoglobulin (Ig)M monoclonal antibody (MAb) was produced against surface antigens from an anastomosis group (AG) 4 isolate of Rhizoctonia solani (teleomorph: Thanatephorus cucumeris). Ascites were produced in mice using GD2 hybridoma cells and used to develop a rapid immunochromatographic lateral flow device (LFD) for the detection of antigens from R. solani and certain related Rhizoctonia spp. The LFD was tested for specificity against surface antigens from related and unrelated soil fungi. Antigens from representative isolates of R. solani AGs 1, 2-1, 2-3, 2-t, 3, 4, 5, 6, 7, 8, 9, 10, 11, and BI gave a positive response in LFD tests, as did antigens from Thanatephorus orchidicola, T. praticola, R. fragariae (teleomorph: Ceratorhiza fragariae), Ceratorhiza goodyerae-repentis, Ceratobasidium cornigerum, and binucleate AGE. Antigens from R. solani AGs 2-2, 2-2IIIB, and 2-2IV and from the related fungi R. carotae, R. cerealis (teleomorph: Ceratobasium cereale), R. crocorum (teleomorph: Helicobasidium brebissonii), R. oryzae (teleomorph Waitea circinata), and R. zeae gave negative responses, as did antigens from a range of unrelated fungi and oomycetes including Fusarium, Gliocladium, Trichoderma, Pythium, and Phytophthora spp. The usefulness of the LFD to detect R. solani was demonstrated in soils naturally infested with R. solani AG3. There was close agreement between results of LFD tests and conventional plate enrichment tests employing selective medium. The specificity of the technique was confirmed by polymerase chain reaction PCR using R. solani AG3-specific primers and by analyses based on sequences of the internal transcribed spacer (ITS)1-5.8S-ITS2 rRNA-encoding regions of unrelated fungi recovered from soil samples. The LFD was used to quantify R. solani AG4 in artificially infested soil samples (chopped potato soil inoculum). Estimates of CFU per gram of soil were derived using a most-probable number technique, which was based on the presence or absence of a detectable signal in the LFD. Estimates of CFU obtained in LFD tests and those obtained in a plate-trapped antigen enzyme-linked immunosorbent assay incorporating MAb GD2 were identical (449 CFU g(-1) of soil). PMID:18943976

Thornton, Christopher R; Groenhof, Andrew C; Forrest, Robert; Lamotte, Richard

2004-03-01

99

Identification of Rhizoctonia solani isolates from sugar beet roots by analyzing the ITS region of ribosomal DNA  

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Full Text Available Rhizoctonia solani (Kühn is one of the most important sugar beet pathogens Rhizoctonia solani anastomosis groups (AGs 2-2 and 4 are proven to be the most common pathogenic strains on sugar beet. AG 2-2 (intraspecific groups IIIB and IV can cause root and crown rot while damping-off of seedlings is most frequently attributed to AG 4. Four isolates of R. solani from sugar beet roots showing characteristic crown and root rot symptoms, collected from different localities in Vojvodina Province, were chosen and compared to the well-characterized R. solani isolate R9, AG 2-2 IV, from the USA. All Vojvodinian isolates showed medium level of pathogenicity and were able to cause crown and root rot symptoms on inoculated sugar beet roots. Based on anastomosis reaction, isolates from Vojvodina did not belong to the AG 2-2 group. Sequencing of the ITS (internal transcribed spacer region of ribosomal DNA was performed on the Vojvodinian isolates from R9 in order to determine their relatedness. Sequence analysis showed that these isolates were different than R9 and were closely related (99-100% sequence homology to anastomosis group 4, subgroup HG II.

Stojšin Vera B.

2007-01-01

100

Mobile elements and mitochondrial genome expansion in the soil fungus and potato pathogen Rhizoctonia solani AG-3.  

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The soil fungus Rhizoctonia solani is an economically important pathogen of agricultural and forestry crops. Here, we present the complete sequence and analysis of the mitochondrial genome of R. solani, field isolate Rhs1AP. The genome (235 849 bp) is the largest mitochondrial genome of a filamentous fungus sequenced to date and exhibits a rich accumulation of introns, novel repeat sequences, homing endonuclease genes, and hypothetical genes. Stable secondary structures exhibited by repeat sequences suggest that they comprise functional, possibly catalytic RNA elements. RNA-Seq expression profiling confirmed that the majority of homing endonuclease genes and hypothetical genes are transcriptionally active. Comparative analysis suggests that the mitochondrial genome of R. solani is an example of a dynamic history of expansion in filamentous fungi. PMID:24461055

Losada, Liliana; Pakala, Suman B; Fedorova, Natalie D; Joardar, Vinita; Shabalina, Svetlana A; Hostetler, Jessica; Pakala, Suchitra M; Zafar, Nikhat; Thomas, Elizabeth; Rodriguez-Carres, Marianela; Dean, Ralph; Vilgalys, Rytas; Nierman, William C; Cubeta, Marc A

2014-03-01

 
 
 
 
101

In vitro attachment of phylloplane yeasts to Botrytis cinerea, Rhizoctonia solani, and Sclerotinia homoeocarpa.  

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The ability of yeasts to attach to hyphae or conidia of phytopathogenic fungi has been speculated to contribute to biocontrol activity on plant surfaces. Attachment of phylloplane yeasts to Botrytis cinerea, Rhizoctonia solani, and Sclerotinia homoeocarpa was determined using in vitro attachment assays. Yeasts were incubated for 2 d on potato dextrose agar (PDA) prior to experimentation. A total of 292 yeasts cultured on PDA were screened for their ability to attach to conidia of B. cinerea; 260 isolates (89.1%) attached to conidia forming large aggregates of cells, and 22 isolates (7.5%) weakly attached to conidia with 1 or 2 yeast cells attached to a few conidia. Ten yeasts (3.4%), including 8 isolates of Cryptococcus laurentii, 1 isolate of Cryptococcus flavescens, and an unidentified species of Cryptococcus, failed to attach to conidia. All non-attaching yeasts produced copious extracellular polysaccharide (EPS) on PDA. Seventeen yeast isolates did not attach to hyphal fragments of B. cinerea, R. solani, and S. homoeocarpa after a 1 h incubation, but attachment was observed after 24 h. Culture medium, but not culture age, significantly affected the attachment of yeast cells to conidia of B. cinerea. The 10 yeast isolates that did not attach to conidia when grown on agar did attach to conidia (20%-57% of conidia with attached yeast cells) when cultured in liquid medium. Attachment of the biocontrol yeast Rhodotorula glutinis PM4 to conidia of B. cinerea was significantly greater at 1 x 10(7) yeast cells x mL(-1) than at lower concentrations of yeast cells. The ability of yeast cells to attach to fungal conidia or hyphae appears to be a common phenotype among phylloplane yeasts. PMID:15714235

Allen, Tom W; Burpee, Leon L; Buck, James W

2004-12-01

102

Mechanism of the generation of new somatic compatibility groups within Thanatephorus cucumeris (Rhizoctonia solani).  

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Single-basidiospore isolates (SBIs) were obtained from field isolates of Thanatephorus cucumeris (Rhizoctonia solani) AG-1 IC and AG-2-2 IV. Formation of distinctive tufts, a recognized feature of heterokaryon synthesis, was observed, and isolates derived from hyphal-tipped tuft hyphae were obtained following pairings between various strains. Three distinctive types of tufts were formed: the fibrous type of mating-compatible homokaryon-homokaryon (Hom-Hom) pairings, the sparse type between heterokaryon-homokaryon (Het-Hom) pairings originating from one parent, and the compact type between Het-Hom pairings originating from different parents. Amplified Fragment Length Polymorphism (AFLP) profile of fingerprints of these tuft isolates verified that they were all heterokaryotic. Because of heterokaryotic vigor, the growth and pathogenicity of the majority of tuft isolates increased compared with their contributing SBIs. New somatic compatibility groups (SCGs) that were different from parental field isolates occurred following heterokaryon formation within T. cucumeris. Tuft isolates produced by Hom-Hom and Het-Hom pairings among isolates of different parents yielded no somatic compatibility with the original parent isolates and a high frequency of new SCGs (62-100%). This was in contrast to those produced by Hom-Hom and Het-Hom pairings among isolates with a common parent that yielded only 12-37% new SCGs. The SCG diversity of R. solani in the field may be attributed to new fitter heterokaryons formed between a heterokaryon of one pair of parents and a homokaryon of another parent pair. This mechanism greatly contributes to genetic diversity in the field and accounts for the failure to recover the expected distribution of SCGs from a field population. PMID:23995511

Qu, Ping; Saldajeno, Mary Grace B; Hyakumachi, Mitsuro

2013-01-01

103

Sobrevivência de micélio e escleródios de Rhizoctonia solani tratados com Trichoderma spp., em restos de cultura de Eucalyptus sp. Survival of Rhizoctonia solani mycelia and sclerotia treated with Trichoderma spp., in Eucalyp]tus sp. litter  

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Full Text Available Este trabalho objetivou estudar a sobrevivência de micélio e escleródios de Rhizoctonia solani AG1-1C, em restos de cultura de eucalipto (Eucalyptus spp. e avaliar a eficiência dos isolados Trichoderma longibrachiatum (UFV-1 e T. inhamatum (UFV-2 e UFV-3, comprovadamente antagônicos a R. solani, em reduzir a sobrevivência do patógeno, em condições de campo. Ao longo de 12 meses de avaliação, a sobrevivência de R. solani em folhas de eucalipto infetadas não foi afetada por fatores ambientes e tampouco por possíveis antagonistas de ocorrência natural. Por outro lado, a sobrevivência dos escleródios decresceu progressivamente, atingindo cerca de 26%. Não se constatou influência dos isolados de Trichoderma spp. na sobrevivência de R. solani em folhas infetadas de eucalipto. Entretanto, redução significativa e contínua na viabilidade de escleródios, foi observada, equiparando-se ao tratamento com fungicida, aos 25 dias após inoculação dos antagonistas, sendo os três isolados igualmente efetivos. Já, a sobrevivência no tratamento com fungicida, atingiu níveis significativamente baixos na primeira avaliação, mas sua eficiência foi reduzida ao longo do período experimental. Redução progressiva e contínua na sobrevivência de escleródios da testemunha foi também constatada, mas inferior a quaisquer dos tratamentos.The survival of mycelium and sclerotia of Rhizoctonia solani AG1-1C was studied in Eucalyptus sp. litter treated with the antagonists Trichoderma longibrachiatum (UFV-1 and T. inhamatum (UFV-2 and UFV-3 isolates. For 12 months, R. solani survival in Rhizoctonia infected eucalypt leaves, was apparently not affected by environmental factors, nor by possible naturally occurring antagonists. On the other hand, the sclerotial rate survival decreased progressively reaching 26%. The influence of Trichoderma spp. isolates did not affect R. solani survival in eucalypt-infected leaves, but significant and continuous reduction of sclerotia viability was observed when compared to captan treatment, 25 days after treatment with the antagonists. The survival in the fungicide treatment reached significantly low levels in the first evaluation, but its efficiency decreased with time. Progressive reduction and continuous survival of sclerotia was detected in the control as well, but significantly less than any other treatment.

Sandra Kunieda-Alonso

2005-04-01

104

Sobrevivência de micélio e escleródios de Rhizoctonia solani tratados com Trichoderma spp., em restos de cultura de Eucalyptus sp. / Survival of Rhizoctonia solani mycelia and sclerotia treated with Trichoderma spp., in Eucalyp]tus sp. litter  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho objetivou estudar a sobrevivência de micélio e escleródios de Rhizoctonia solani AG1-1C, em restos de cultura de eucalipto (Eucalyptus spp.) e avaliar a eficiência dos isolados Trichoderma longibrachiatum (UFV-1) e T. inhamatum (UFV-2 e UFV-3), comprovadamente antagônicos a R. solani, [...] em reduzir a sobrevivência do patógeno, em condições de campo. Ao longo de 12 meses de avaliação, a sobrevivência de R. solani em folhas de eucalipto infetadas não foi afetada por fatores ambientes e tampouco por possíveis antagonistas de ocorrência natural. Por outro lado, a sobrevivência dos escleródios decresceu progressivamente, atingindo cerca de 26%. Não se constatou influência dos isolados de Trichoderma spp. na sobrevivência de R. solani em folhas infetadas de eucalipto. Entretanto, redução significativa e contínua na viabilidade de escleródios, foi observada, equiparando-se ao tratamento com fungicida, aos 25 dias após inoculação dos antagonistas, sendo os três isolados igualmente efetivos. Já, a sobrevivência no tratamento com fungicida, atingiu níveis significativamente baixos na primeira avaliação, mas sua eficiência foi reduzida ao longo do período experimental. Redução progressiva e contínua na sobrevivência de escleródios da testemunha foi também constatada, mas inferior a quaisquer dos tratamentos. Abstract in english The survival of mycelium and sclerotia of Rhizoctonia solani AG1-1C was studied in Eucalyptus sp. litter treated with the antagonists Trichoderma longibrachiatum (UFV-1) and T. inhamatum (UFV-2 and UFV-3) isolates. For 12 months, R. solani survival in Rhizoctonia infected eucalypt leaves, was appare [...] ntly not affected by environmental factors, nor by possible naturally occurring antagonists. On the other hand, the sclerotial rate survival decreased progressively reaching 26%. The influence of Trichoderma spp. isolates did not affect R. solani survival in eucalypt-infected leaves, but significant and continuous reduction of sclerotia viability was observed when compared to captan treatment, 25 days after treatment with the antagonists. The survival in the fungicide treatment reached significantly low levels in the first evaluation, but its efficiency decreased with time. Progressive reduction and continuous survival of sclerotia was detected in the control as well, but significantly less than any other treatment.

Sandra, Kunieda-Alonso; Acelino C., Alfenas; Luiz A., Maffia.

105

In vitro and glasshouse biocontrol of Rhizoctonia solani with improved strains of Trichoderma spp. / Biocontrol de Rhizoctonia solani in vivo y en invernadero, con cepas mejoradas de Trichoderma spp.  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in spanish J.R. Montealegre, F. Ochoa, X. Besoain, R. Herrera y L.M. Pérez. 2014. Biocontrol de Rhizoctonia solani in vivo y en invernadero, con cepas mejoradas de Trichoderma spp. Cien. Inv. Agr. 41(2):197-206. Se comparó la capacidad de cepas de Trichoderma spp., obtenidas previamente por fusión de protoplas [...] tos, con la de sus correspondientes cepas parentales, para biocontrolar a Rhizoctonia solani. El efecto biocontrolador se analizó sobre dos cepas de R. solani: 509 (GA 2-1) y 618 (GA 4). Las cepas producto de fusión de protoplastos de Trichoderma spp. fueron más efectivas que al menos una de las correspondientes cepas parentales. La inhibición más alta en experimentos de cultivos duales, se observó con las cepas ThF2-1 (89,79%), ThF3-3 (90,55%), ThF4-15 (91,75%) y ThF5-8 (77,67%) sobre R. solani 509; mientras que el efecto biocontrolador sobre R. solani 618, sólo logró un 60,19% de inhibición con la cepa ThF2-1. El efecto inhibidor del desarrollo se debió principalmente a la secreción de metabolitos difusibles. El porcentaje de mortalidad y nivel de cancro en plantas de tomate se evaluó en experimentos de invernadero, en los que todas las cepas producto de la fusión de protoplastos de Trichoderma spp. suprimieron la mortalidad de plantas de tomate, y solamente ThF2-1 y ThF5-8 disminuyeron significativamente el nivel de cancro. Abstract in english J.R. Montealegre, F. Ochoa, X. Besoain, R. Herrera, and L.M. Pérez. 2014. In vitro and glasshouse biocontrol of Rhizoctonia solani with improved strains of Trichoderma spp. Cien. Inv. Agr. 41(2):197-206. The potential of Trichoderma spp. fusants for the biocontrol of Rhizoctonia solani was compared [...] with the ability of their corresponding parental strains. Their effect was tested in vitro using two R. solani strains, 509 (AG 2-1) and 618 (AG 4). The highest inhibitions in growth in dual cultures were obtained with the ThF2-1 (89.79%), ThF3-3 (90.55%), ThF4-15 (91.75%) and ThF5-8 (77.67%) fusants on R. solani 509; only ThF2-1 was able to inhibit the growth of R. solani 618 (60.19%). The inhibitory effect on growth was mainly due to diffusible metabolites. Percent mortality and canker level in tomato plants were evaluated in glasshouse experiments where all of the evaluated fusants suppressed plant mortality, but only ThF2-1 and ThF5-8 significantly decreased the canker level.

Jaime R, Montealegre; Fabián, Ochoa; Ximena, Besoain; Rodrigo, Herrera; Luz M, Pérez.

106

Development of a difenoconazole/propiconazole microemulsion and its antifungal activities against Rhizoctonia solani AG1-IA.  

Science.gov (United States)

According to its physical and chemical properties, the composition of difenoconazole/propiconazole microemulsion was as follows: xylene as solvent, emulsifier HSH as surfactant and methanol as cosurfactant. The optimal formulation of difenoconazole/propiconazole microemulsion was oil/SAA/water = 1/2/5 (w/w), in which the SAA consisted of emulsifier HSH and methanol with ratio of 3/2 (w/w). The cloud point of difenoconazole/propiconazole microemulsion was 70 degrees C and its effective ingredient content was 2.5% measured by High Performance Liquid Chromatography (HPLC). Its heat storage stability was studied according to the standards. The decomposition rates of the difenoconazole/propiconazole microemulsion were merely 2.45%, 2.63% respectively and met the Food and Agriculture Organization (FAO) standards of pesticide microemulsion. Investigated by Transmission Electron Microscopy (TEM) the particle size of difenoconazole/propiconazole microemulsion was 90-140 nm and its antifungal activities against Rhizoctonia solani AG1-IA were tested and compared with that of Meiyu. We found that the inhibition rates in the difenoconazole/propiconazole microemulsion treatment group were significantly higher than that of the emulsion group with the same content of effective ingredients and the study also revealed that its inhibiting ability on the formation and germination of sclerotia was significant. PMID:22822543

Leng, Pengfei; Zhang, Zhiming; Li, Qian; Zhang, Yunsong; Zhao, Maojun; Pan, Guangtang

2012-06-01

107

Preparation and characterization of nano-sized calcium carbonate as controlled release pesticide carrier for validamycin against Rhizoctonia solani  

International Nuclear Information System (INIS)

Nano-sized calcium carbonate (nano-CC) was studied in terms of acting as a carrier for a pesticide. Nano-CC was prepared by reaction of calcium chloride and sodium carbonate by the reversed-phase microemulsion method and then loaded with the pesticide validamycin. The resulting material was characterized by X-ray diffraction analysis and scanning electron microscopy. The loading efficiency, sustained-release performance, germicidal efficacy, and stability also were investigated. The size of the loaded nano-CC can be adjusted to between 50 to 200 nm by varying the water/surfactant molar ratio from 30/1 to 10/1, and the loading efficiency can be increased to about 20% by increasing the size of the nano-CC. The material displayed better germicidal efficacy against Rhizoctonia solani compared to conventional technical validamycin after about 7 days, and the time of the release of validamycin was extended to 2 weeks. Given the loading efficiency, stability, sustained-release performance and good environmental compatibility of the material, the method for its preparation may be extended to other hydrophilic pesticide. (author)

108

Genetic Analysis of Banded Leaf and Sheath Blight Resistance (Rhizoctonia Solani In Maize  

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Full Text Available Line × tester analysis involving 12 inbred lines and 5 inbred testers were carried to study the genetics of resistance to banded leaf and sheath blight in maize incited by Rhizoctonia solani in Kharif2010at B.A.U. research farm. Out of seventeen inbreds including five testers, three lines were resistant, twelve lines were moderately resistant and two lines were moderately susceptible. Both additive and dominance components were important in the inheritance of this disease with the predominant role of additive gene action. The inbreds, BAUIM-3, BQPM-2 and BQPM-4 were good general combiners for disease resistance as well as yield. Among the testers, BAUIM-2 was found to be the best general combiner for disease resistance as well as yield. The estimate of specific combining ability effect revealed that the cross combinations, BAU1M-3× CM-150, BAU1M-1×BAU1M-2, BAU1M-4×HKI 193-1, BAU1M-4×HKI163, V341× CM150, BQPM-2× BAU1M-2 and CML161× HKI 193-1 were identified as best cross combinations in respect of disease resistance as well as yield.

Tajwar Izhar

2013-03-01

109

Estudio de Rhizoctonia solani Kühn aislado de papa (Solanum tuberosum L. en los estados Táchira, Mérida, Trujillo y Lara: II. virulencia y caracterización molecular Rhizoctonia solani Kühn isolated from potato in various Venezuelan states: II. Virulence and molecular characterization  

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Full Text Available Rhizoctonia solani ocasiona la enfermedad conocida como rizoctoniosis en el cultivo de la papa y constituye un serio problema en Venezuela. En el país se han identificado los grupos anastomósicos presentes y se ha realizado la caracterización cultural del hongo pero no la molecular ni la de virulencia, por lo que estos objetivos fueron planteados en el presente trabajo. Se utilizaron cuarenta aislamientos obtenidos de los estados Táchira, Mérida, Trujillo y Lara. Se utilizaron las técnicas de RAPD, UPR e ITS para la caracterización molecular, y pruebas de patogenicidad en papa ‘Kennebec’ para determinar la virulencia. Con las tres técnicas moleculares se observaron variaciones genéticas entre las cepas del hongo y se confirmó la presencia de AG-3 y AG-2.1 de R. solani. Las cepas mostraron diferencias significativas en la virulencia, la cual estuvo influenciada por la temperatura.Rhizoctonia solani causes the disease known as rizoctoniosis in potato and it is a serious problem in Venezuela. Anastomosis groups and cultural characterization have been determined in the country, but neither molecular nor virulence characterization. Therefore, the research focused on those two objectives. Forty isolates from Táchira, Merida, Trujillo and Lara States were used on which RAPD, UPR and ITS techniques were performed; also, pathogenicity tests were run on ‘Kennebec’ potato plants. Genetic variability among isolates was observed with all three molecular techniques and presence of AG-3 and AG-2.1 was confirmed. Isolates showed significant difference with regard to virulence, which was influenced by temperature.

Yoleidy Escalona

2012-04-01

110

Control biológico de Rhizoctonia solani en plantas de papa criollaSolanum phureja usando cepas nativas de Pseudomonas fluorescens / BIOCONTROL OF Rhizoctonia solani IN NATIVE POTATO (Solanum phureja) PLANTS USING NATIVE Pseudomonas fluorescens  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Rhizoctonia solani es un hongo fitopatógeno del suelo, el cual produce una reducción significativa del vigor de las plantas y de la producción de tubérculos en cultivos de papa. Es de gran interés la búsqueda de alternativas de manejo de esta enfermedad, especialmente desde la perspectiva de control [...] biológico ya que los cultivos de papa son los mayores consumidores de plaguicidas de origen químicos en Colombia. Con el objeto de obtener una cepa del grupo de las Pseudomonas fluorescentes con la capacidad para reducir los síntomas de la enfermedad producidos por R. solani, se realizó en un estudio previo el aislamiento y caracterización de una colección de aislamientos de Pseudomonas fluorescentes provenientes de diferentes cultivos de la región papera más productiva del país. Seis cepas nativas de P. fluorescens con buena, moderada o ninguna capacidad para inhibir el crecimiento fúngico in vitro fueron seleccionadas. A pesar de las diferencias encontradas en términos de la dinámica y capacidad de colonización, todas las cepas evaluadas indujeron el crecimiento en las plantas de S. phureja y redujeron los síntomas de la enfermedad producidos por R. solani a nivel de invernadero. Nuestros resultados sustentan la conclusión que la asociación de cepas de P. fluorescens con la rizosfera de S. phureja es una alternativa para el manejo de R. solani en papa. Abstract in english Rhizoctonia solani is a soil borne phytopathogen associated with reduced plant vigor and tuber production in potato crops. There is a huge interest to search alternatives of biological control management of this disease, because the potato crops in Colombia are the highest consumers of chemical pest [...] icides in Colombia. In order to obtain a fluorescent Pseudomonas strain with the capacity to reduce the disease symptoms produced by R. solani, determination and isolation of the predominant fluorescent Pseudomonas in several potato crops of the main Colombian producing region was done in a previous study. Six different P. fluorescens strains with none, moderate and high fungal growth inhibition capacity in vitro, were used in this study. Despite of the differences found in the dynamics of colonization and colonization capacity, all evaluated strains induced S. phureja growth and reduced disease symptoms produced by R. solani. Our results support the conclusion that association of P. fluorescens strains with S. phureja rhizosphere is a feasible alternative for the management of R. solani symptoms.

GLORIA, BAUTISTA; HENRY, MENDOZA; DANIEL, URIBE.

2007-06-01

111

High protection of protein kinase NtPK against the phytopatogenic fungus Rhizoctonia solani / La proteína quinasa NtPK confiere alto nivel de protección contra el hongo fitopatógeno Rhizoctonia solani  

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Full Text Available SciELO Cuba | Language: English Abstract in spanish Con el objetivo de identificar los genes involucrados en la resistencia y susceptibilidad de la Nicotiana tabacum al hongo fitopatógeno Rhizoctonia solani, se generaron (a través de librerías substractivas) transcriptos que se expresan diferentemente en cada interacción. Ello permitió el aislamiento [...] de un gen que codifica para una proteína quinasa que se silencia durante la interacción de susceptibilidad y se activa durante la resistencia. La expresión de este gen en plantas de tabaco incrementó significativamente su resistencia frente a un aislado agresivo de R. solani. Sin embargo, el silenciamiento del gen redujo drásticamente la resistencia a una cepa no agresiva de R. solani. Además se evaluaron genes como superóxido dismutasa, hsr203j, quitinasas y fenilalanina amonio-liasa relacionados con la resistencia a enfermedades en plantas de tabaco en las que se sobrexpresa o silencia el gen que codifica para la proteína quinasa. Este gen se puede utilizar para el diseño de una estrategia de resistencia a R. solani en cultivos de tabaco u otras plantas de la familia Solanácea, susceptibles a este fitopatógeno. Abstract in english To identify Nicotiana tabacum genes involved in resistance and susceptibility to the phytopathogenic fungus Rhizoctonia solani, transcripts were generated (by subtractive libraries), which were differentially expressed in each interaction. This enabled isolation of a gene coding for a protein kinase [...] that becomes silent during the susceptibility interaction and is activated during resistance. The expression of this gene in tobacco plants significantly increased resistance against an aggressive isolate of R. solani. However, silencing the gene drastically reduced resistance to a non-aggressive isolate of R. solani. Besides, genes such as: superoxide dismutase, hsr203j, chitinases and phenylalanine ammonia lyase, related with resistance to tobacco plant diseases, in which the gene coding for the protein kinase is overexpressed or silenced, were evaluated. This gene can be used to design a strategy of resistance to R. solani in tobacco cultures or other plants of the Solanaceae family, susceptible to this phytopathogen.

Orlando, Borrás; Osmani, Chacón; Marleny, González; Roxana, Portieles; Ernesto, González; Merardo, Pujol.

2012-12-01

112

Control biológico de Rhizoctonia solani en plantas de papa criollaSolanum phureja usando cepas nativas de Pseudomonas fluorescens BIOCONTROL OF Rhizoctonia solani IN NATIVE POTATO (Solanum phureja PLANTS USING NATIVE Pseudomonas fluorescens  

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Full Text Available Rhizoctonia solani es un hongo fitopatógeno del suelo, el cual produce una reducción significativa del vigor de las plantas y de la producción de tubérculos en cultivos de papa. Es de gran interés la búsqueda de alternativas de manejo de esta enfermedad, especialmente desde la perspectiva de control biológico ya que los cultivos de papa son los mayores consumidores de plaguicidas de origen químicos en Colombia. Con el objeto de obtener una cepa del grupo de las Pseudomonas fluorescentes con la capacidad para reducir los síntomas de la enfermedad producidos por R. solani, se realizó en un estudio previo el aislamiento y caracterización de una colección de aislamientos de Pseudomonas fluorescentes provenientes de diferentes cultivos de la región papera más productiva del país. Seis cepas nativas de P. fluorescens con buena, moderada o ninguna capacidad para inhibir el crecimiento fúngico in vitro fueron seleccionadas. A pesar de las diferencias encontradas en términos de la dinámica y capacidad de colonización, todas las cepas evaluadas indujeron el crecimiento en las plantas de S. phureja y redujeron los síntomas de la enfermedad producidos por R. solani a nivel de invernadero. Nuestros resultados sustentan la conclusión que la asociación de cepas de P. fluorescens con la rizosfera de S. phureja es una alternativa para el manejo de R. solani en papa.Rhizoctonia solani is a soil borne phytopathogen associated with reduced plant vigor and tuber production in potato crops. There is a huge interest to search alternatives of biological control management of this disease, because the potato crops in Colombia are the highest consumers of chemical pesticides in Colombia. In order to obtain a fluorescent Pseudomonas strain with the capacity to reduce the disease symptoms produced by R. solani, determination and isolation of the predominant fluorescent Pseudomonas in several potato crops of the main Colombian producing region was done in a previous study. Six different P. fluorescens strains with none, moderate and high fungal growth inhibition capacity in vitro, were used in this study. Despite of the differences found in the dynamics of colonization and colonization capacity, all evaluated strains induced S. phureja growth and reduced disease symptoms produced by R. solani. Our results support the conclusion that association of P. fluorescens strains with S. phureja rhizosphere is a feasible alternative for the management of R. solani symptoms.

GLORIA BAUTISTA

2007-06-01

113

High protection of protein kinase NtPK against the phytopatogenic fungus Rhizoctonia solani / La proteína quinasa NtPK confiere alto nivel de protección contra el hongo fitopatógeno Rhizoctonia solani  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: English Abstract in spanish Con el objetivo de identificar los genes involucrados en la resistencia y susceptibilidad de la Nicotiana tabacum al hongo fitopatógeno Rhizoctonia solani, se generaron (a través de librerías substractivas) transcriptos que se expresan diferentemente en cada interacción. Ello permitió el aislamiento [...] de un gen que codifica para una proteína quinasa que se silencia durante la interacción de susceptibilidad y se activa durante la resistencia. La expresión de este gen en plantas de tabaco incrementó significativamente su resistencia frente a un aislado agresivo de R. solani. Sin embargo, el silenciamiento del gen redujo drásticamente la resistencia a una cepa no agresiva de R. solani. Además se evaluaron genes como superóxido dismutasa, hsr203j, quitinasas y fenilalanina amonio-liasa relacionados con la resistencia a enfermedades en plantas de tabaco en las que se sobrexpresa o silencia el gen que codifica para la proteína quinasa. Este gen se puede utilizar para el diseño de una estrategia de resistencia a R. solani en cultivos de tabaco u otras plantas de la familia Solanácea, susceptibles a este fitopatógeno. Abstract in english To identify Nicotiana tabacum genes involved in resistance and susceptibility to the phytopathogenic fungus Rhizoctonia solani, transcripts were generated (by subtractive libraries), which were differentially expressed in each interaction. This enabled isolation of a gene coding for a protein kinase [...] that becomes silent during the susceptibility interaction and is activated during resistance. The expression of this gene in tobacco plants significantly increased resistance against an aggressive isolate of R. solani. However, silencing the gene drastically reduced resistance to a non-aggressive isolate of R. solani. Besides, genes such as: superoxide dismutase, hsr203j, chitinases and phenylalanine ammonia lyase, related with resistance to tobacco plant diseases, in which the gene coding for the protein kinase is overexpressed or silenced, were evaluated. This gene can be used to design a strategy of resistance to R. solani in tobacco cultures or other plants of the Solanaceae family, susceptible to this phytopathogen.

Orlando, Borrás; Osmani, Chacón; Marleny, González; Roxana, Portieles; Ernesto, González; Merardo, Pujol.

114

Control biológico de Rhizoctonia solani en plantas de papa criollaSolanum phureja usando cepas nativas de Pseudomonas fluorescens / BIOCONTROL OF Rhizoctonia solani IN NATIVE POTATO (Solanum phureja) PLANTS USING NATIVE Pseudomonas fluorescens  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Rhizoctonia solani es un hongo fitopatógeno del suelo, el cual produce una reducción significativa del vigor de las plantas y de la producción de tubérculos en cultivos de papa. Es de gran interés la búsqueda de alternativas de manejo de esta enfermedad, especialmente desde la perspectiva de control [...] biológico ya que los cultivos de papa son los mayores consumidores de plaguicidas de origen químicos en Colombia. Con el objeto de obtener una cepa del grupo de las Pseudomonas fluorescentes con la capacidad para reducir los síntomas de la enfermedad producidos por R. solani, se realizó en un estudio previo el aislamiento y caracterización de una colección de aislamientos de Pseudomonas fluorescentes provenientes de diferentes cultivos de la región papera más productiva del país. Seis cepas nativas de P. fluorescens con buena, moderada o ninguna capacidad para inhibir el crecimiento fúngico in vitro fueron seleccionadas. A pesar de las diferencias encontradas en términos de la dinámica y capacidad de colonización, todas las cepas evaluadas indujeron el crecimiento en las plantas de S. phureja y redujeron los síntomas de la enfermedad producidos por R. solani a nivel de invernadero. Nuestros resultados sustentan la conclusión que la asociación de cepas de P. fluorescens con la rizosfera de S. phureja es una alternativa para el manejo de R. solani en papa. Abstract in english Rhizoctonia solani is a soil borne phytopathogen associated with reduced plant vigor and tuber production in potato crops. There is a huge interest to search alternatives of biological control management of this disease, because the potato crops in Colombia are the highest consumers of chemical pest [...] icides in Colombia. In order to obtain a fluorescent Pseudomonas strain with the capacity to reduce the disease symptoms produced by R. solani, determination and isolation of the predominant fluorescent Pseudomonas in several potato crops of the main Colombian producing region was done in a previous study. Six different P. fluorescens strains with none, moderate and high fungal growth inhibition capacity in vitro, were used in this study. Despite of the differences found in the dynamics of colonization and colonization capacity, all evaluated strains induced S. phureja growth and reduced disease symptoms produced by R. solani. Our results support the conclusion that association of P. fluorescens strains with S. phureja rhizosphere is a feasible alternative for the management of R. solani symptoms.

GLORIA, BAUTISTA; HENRY, MENDOZA; DANIEL, URIBE.

115

Queima foliar e tombamento de mudas em plantas medicinais causadas por Rhizoctonia solani AG1 - 1B Leaf blight and seedling damping-off of medicinal plants caused by Rhizoctonia solani AG1 - 1B  

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Full Text Available Recentemente, em plantas medicinais da família Labiatae (Rosmarinus officinalis, Lavandula sp., Salvia officinalis e Thymus vulgaris, constatou-se tombamento de mudas em pós-emergência e queima foliar ascendente. Em isolamentos efetuados a partir de tecidos doentes, observou-se o desenvolvimento de um fungo com hifas ramificadas em ângulo de aproximadamente 90º, constrição na base da ramificação, septo próximo à inserção da hifa lateral e outras características típicas do gênero Rhizoctonia. Inoculou-se o fungo em plantas sadias cultivadas em vasos plásticos. Naquelas inoculadas por pincelamento de inóculo, ocorreu queima foliar de forma generalizada aos quatro dias da inoculação, enquanto nas inoculadas pela deposição de inóculo na superfície dos vasos, houve queima foliar ascendente, como observado em condições naturais, aos dez dias da inoculação. Com base na morfologia da colônia, crescimento micelial, número de núcleos, identificação do grupo e subgrupo de anastomose e da fase teleomórfica, o patógeno foi caracterizado como Rhizoctonia solani (fase anamórfica de Thanatephorus cucumeris. Com a reprodução dos sintomas da doença por inoculação artificial nas mudas e o reisolamento, em meio de batata dextrose ágar (BDA, do mesmo fungo a partir de tecidos doentes confirmou-se R. solani como o agente etiológico da doença.Recently, seedling damping off and blight progressing from old to young leaves were found on medicinal plants of the family Labiatae (Rosmarinus officinalis, Lavandula sp., Salvia officinalis and Thymus vulgaris. A fungus was isolated from diseased tissues, in which the hyphae had diameter, ramification angle of about 90º, basal constriction, a septum next to the lateral hyphae, and other typical characteristics of the genus Rhizoctonia. The fungus was inoculated on healthy plants cultivated in plastic pots by brushing inoculum suspension on leaves (brushing or by pouring the inoculum suspension on the surface of pots (soil infestation. On plants inoculated by brushing, disease symptoms occurred on all leaves four days after inoculation. On plants inoculated by soil infestation, leaf blight continued to ascent for ten days after inoculation under natural conditions. Based on colony morphology, mycelial growth, number of nuclei, identification of anastomosys group and subgroup, and on the teleomorph, the pathogen was considered to be Rhizoctonia solani (anamorph of Thanatephorus cucumeris. As disease symptoms were reproduced by artificial inoculation on plants and the fungus was reisolated on potato dextrose agar (PDA from diseased tissues, R. solani was confirmed to be the causal agent of the disease.

Reginaldo G. Mafia

2005-06-01

116

Queima foliar e tombamento de mudas em plantas medicinais causadas por Rhizoctonia solani AG1 - 1B / Leaf blight and seedling damping-off of medicinal plants caused by Rhizoctonia solani AG1 - 1B  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Recentemente, em plantas medicinais da família Labiatae (Rosmarinus officinalis, Lavandula sp., Salvia officinalis e Thymus vulgaris), constatou-se tombamento de mudas em pós-emergência e queima foliar ascendente. Em isolamentos efetuados a partir de tecidos doentes, observou-se o desenvolvimento de [...] um fungo com hifas ramificadas em ângulo de aproximadamente 90º, constrição na base da ramificação, septo próximo à inserção da hifa lateral e outras características típicas do gênero Rhizoctonia. Inoculou-se o fungo em plantas sadias cultivadas em vasos plásticos. Naquelas inoculadas por pincelamento de inóculo, ocorreu queima foliar de forma generalizada aos quatro dias da inoculação, enquanto nas inoculadas pela deposição de inóculo na superfície dos vasos, houve queima foliar ascendente, como observado em condições naturais, aos dez dias da inoculação. Com base na morfologia da colônia, crescimento micelial, número de núcleos, identificação do grupo e subgrupo de anastomose e da fase teleomórfica, o patógeno foi caracterizado como Rhizoctonia solani (fase anamórfica de Thanatephorus cucumeris). Com a reprodução dos sintomas da doença por inoculação artificial nas mudas e o reisolamento, em meio de batata dextrose ágar (BDA), do mesmo fungo a partir de tecidos doentes confirmou-se R. solani como o agente etiológico da doença. Abstract in english Recently, seedling damping off and blight progressing from old to young leaves were found on medicinal plants of the family Labiatae (Rosmarinus officinalis, Lavandula sp., Salvia officinalis and Thymus vulgaris). A fungus was isolated from diseased tissues, in which the hyphae had diameter, ramific [...] ation angle of about 90º, basal constriction, a septum next to the lateral hyphae, and other typical characteristics of the genus Rhizoctonia. The fungus was inoculated on healthy plants cultivated in plastic pots by brushing inoculum suspension on leaves (brushing) or by pouring the inoculum suspension on the surface of pots (soil infestation). On plants inoculated by brushing, disease symptoms occurred on all leaves four days after inoculation. On plants inoculated by soil infestation, leaf blight continued to ascent for ten days after inoculation under natural conditions. Based on colony morphology, mycelial growth, number of nuclei, identification of anastomosys group and subgroup, and on the teleomorph, the pathogen was considered to be Rhizoctonia solani (anamorph of Thanatephorus cucumeris). As disease symptoms were reproduced by artificial inoculation on plants and the fungus was reisolated on potato dextrose agar (PDA) from diseased tissues, R. solani was confirmed to be the causal agent of the disease.

Reginaldo G., Mafia; Acelino C., Alfenas; Luiz A., Maffia; Gizella M., Ventura; Eraclides M., Ferreira; Irislei F., Neves; Cláudia A., Vanetti; Clarice, Silva.

2005-06-01

117

Queima foliar e tombamento de mudas em plantas medicinais causadas por Rhizoctonia solani AG1 - 1B / Leaf blight and seedling damping-off of medicinal plants caused by Rhizoctonia solani AG1 - 1B  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Recentemente, em plantas medicinais da família Labiatae (Rosmarinus officinalis, Lavandula sp., Salvia officinalis e Thymus vulgaris), constatou-se tombamento de mudas em pós-emergência e queima foliar ascendente. Em isolamentos efetuados a partir de tecidos doentes, observou-se o desenvolvimento de [...] um fungo com hifas ramificadas em ângulo de aproximadamente 90º, constrição na base da ramificação, septo próximo à inserção da hifa lateral e outras características típicas do gênero Rhizoctonia. Inoculou-se o fungo em plantas sadias cultivadas em vasos plásticos. Naquelas inoculadas por pincelamento de inóculo, ocorreu queima foliar de forma generalizada aos quatro dias da inoculação, enquanto nas inoculadas pela deposição de inóculo na superfície dos vasos, houve queima foliar ascendente, como observado em condições naturais, aos dez dias da inoculação. Com base na morfologia da colônia, crescimento micelial, número de núcleos, identificação do grupo e subgrupo de anastomose e da fase teleomórfica, o patógeno foi caracterizado como Rhizoctonia solani (fase anamórfica de Thanatephorus cucumeris). Com a reprodução dos sintomas da doença por inoculação artificial nas mudas e o reisolamento, em meio de batata dextrose ágar (BDA), do mesmo fungo a partir de tecidos doentes confirmou-se R. solani como o agente etiológico da doença. Abstract in english Recently, seedling damping off and blight progressing from old to young leaves were found on medicinal plants of the family Labiatae (Rosmarinus officinalis, Lavandula sp., Salvia officinalis and Thymus vulgaris). A fungus was isolated from diseased tissues, in which the hyphae had diameter, ramific [...] ation angle of about 90º, basal constriction, a septum next to the lateral hyphae, and other typical characteristics of the genus Rhizoctonia. The fungus was inoculated on healthy plants cultivated in plastic pots by brushing inoculum suspension on leaves (brushing) or by pouring the inoculum suspension on the surface of pots (soil infestation). On plants inoculated by brushing, disease symptoms occurred on all leaves four days after inoculation. On plants inoculated by soil infestation, leaf blight continued to ascent for ten days after inoculation under natural conditions. Based on colony morphology, mycelial growth, number of nuclei, identification of anastomosys group and subgroup, and on the teleomorph, the pathogen was considered to be Rhizoctonia solani (anamorph of Thanatephorus cucumeris). As disease symptoms were reproduced by artificial inoculation on plants and the fungus was reisolated on potato dextrose agar (PDA) from diseased tissues, R. solani was confirmed to be the causal agent of the disease.

Reginaldo G., Mafia; Acelino C., Alfenas; Luiz A., Maffia; Gizella M., Ventura; Eraclides M., Ferreira; Irislei F., Neves; Cláudia A., Vanetti; Clarice, Silva.

118

Genetic analyses of Rhizoctonia solani isolates from Phaseolus vulgaris grown in the Atlantic Rainforest Region of São Paulo, Brazil Análise genética de isolados de Rhizoctonia solani de Phaseolus vulgaris da região da Mata Atlântica de São Paulo, Brasil  

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Full Text Available Rhizoctonia solani isolates obtained from common beans (Phaseolus vulgaris grown in the mountainous Atlantic Rainforest (Mata Atlântica region of São Paulo, Brazil, were analyzed to determine their genetic diversity using internal transcribed spacer (ITS, microsatellite and telomere sequence-based PCR primers. Restriction digestion of the ITS1/5.8S/ITS2 ribosomal regions yielded unique banding patterns specific for AG4 and its subgroups. The ITS restriction digestion (ITS/RFLP, telomere and microsatellite primers identified five to 11 genotypes within the isolates of R. solani. While all isolates were pathogenic on beans, there was no correlation found between genotypic differences and pathogenicity. The different PCR primers revealed a number of isolates that were genetically similar. Some of these genetic groups were supported by more than one of the primers utilized in this study, thus confirming their relationship.A diversidade genética de 18 isolados de Rhizoctonia solani de feijoeiro (Phaseolus vulgaris cultivado na Mata Atlântica de São Paulo, Brasil foi avaliada através da análise do espaçadores transcritos internos (ITS, microssatélites e iniciadores ("primers" específicos para sequências teloméricas. A análise de restrição da região ribossomal ITS1/5,8S/ITS2 produziu um padrão de bandas específico para o grupo de anastomose 4 (GA 4 e seus subgrupos. O padrão obtido com ITS/RFLP, microsatélites e os iniciadores teloméricos permitiram identificar cinco a 11 genótipos entre os isolados de R. solani. Enquanto todos os isolados foram patogênicos em feijoeiro, não houve correlação entre patogenicidade e diferenças genotípicas. Os diferentes iniciadores para PCR revelaram que muitos isolados são geneticamente similares, análise esta que pode ser confirmada por mais de um conjunto de iniciadores, fortalecendo a relação deste agrupamento.

LYNDEL W. MEINHARDT

2002-06-01

119

Regulation of L-phenylalanine ammonia-lyase from Rhizoctonia solani.  

Science.gov (United States)

Maximal levels of L-henylalanine ammonia-lyase activity were observed when the mycelial felts of Rhizoctonia solani were grown for 4.5 days on Byrde synthetic medium containing 3.5% glucose and 0.3% L-phenylalanine, Differential centrifugation studies have indicated that the enzyme is localized in the soluble fraction. The time course of induction of L-phenylalanine ammonia-lyase activity by L-phenylalanine showed a lag period of 1 to 1.5 h and reached a maximum around 4 to 6 h after the addition of the inducer to the medium. L-Phenylalanine, L-tyrosine, and L-tryptophan were nearly equally efficient inducers of the enzyme. D-Phenylalanine was as efficient as the L-isomer, whereas D-tyrosine was a poor inducer. Light, gibberellic acid, indole 3-acetic acid, and kinetin had no effect on the induction of L-phenylalanine ammonia-lyase activity. Cycloheximide did not inhibit the uptake of amino acids by the mycelia but completely blocked the incorporation of radioactive amino acids into soluble proteins and the development of L-phenylalanine ammonia-lyase activity. Actinomycin D inhibited both the incorporation of 32P into ribonucleic acid and the enzyme activity. Conclusive evidence for de novo synthesis of L-phenylalanine ammonia-lyase was obtained by the incorporation of radioactive amino acids into the enzyme. Electrophoretic analysis of the purified preparation showed a single protein band that coincided with radioactivity and L-phenylalanine ammonia-lyase activity. Glucose and intermediates of the tricarboxylic acid cycle, like citric acid, alpha-ketoglutaric acid, and succinic acid, and the metabolites of L-phenylalanine, like o-coumaric acid, o-hydroxyphenylacetic acid, and protocatechuic acid, significantly repressed L-phenylalanine ammonia-lyase activity. The observed repression was not relieved by cyclic adenosine 5'-triphosphate. PMID:1262311

Kalghatgi, K K; Subba Rao, P V

1976-05-01

120

A novel mycovirus closely related to viruses in the genus Alphapartitivirus confers hypovirulence in the phytopathogenic fungus Rhizoctonia solani.  

Science.gov (United States)

We report here the biological and molecular attributes of a novel dsRNA mycovirus designated Rhizoctonia solani partitivirus 2 (RsPV2) from strain GD-11 of R. solani AG-1 IA, the causal agent of rice sheath blight. The RsPV2 genome comprises two dsRNAs, each possessing a single ORF. Phylogenetic analyses indicated that this novel virus species RsPV2 showed a high sequence identity with the members of genus Alphapartitivirus in the family Partitiviridae, and formed a distinct clade distantly related to the other genera of Partitiviridae. Introduction of purified RsPV2 virus particles into protoplasts of a virus-free virulent strain GD-118 of R. solani AG-1 IA resulted in a derivative isogenic strain GD-118T with reduced mycelial growth and hypovirulence to rice leaves. Taken together, it is concluded that RsPV2 is a novel dsRNA virus belonging to Alphapartitivirus, with potential role in biological control of R. solani. PMID:24889241

Zheng, Li; Zhang, Meiling; Chen, Qiguang; Zhu, Minghai; Zhou, Erxun

2014-05-01

 
 
 
 
121

Mass spectrometry identification of antifungal lipopeptides from Bacillus sp. BCLRB2 against Rhizoctonia solani and Sclerotinia sclerotiorum.  

Science.gov (United States)

This work aims to characterize the bioactive molecules produced by an antagonistic Bacillus sp. strain BCLRB2 isolated from healthy leaves of olive tree against Rhizoctonia solani and Sclerotinia sclerotiorum. The bacterial strain isolated showed a high and persistent antifungal activity against the two pathogens. The free-cell supernatant showed also a high antifungal activity against R. solani and at a lower extent against S. sclerotiorum. The partial purification of the antifungal substances with methanol gradient applied to C18 column binding the Bacillus BCLRB2 culture supernatant showed that the 20% and 60% methanol fractions had a high and specific activity against S. sclerotiorum and R. solani, respectively. The mass spectrometry identification of the compounds in the fraction specifically active against S. sclerotiorum revealed the presence of bacillomycin D C16 as a major lipopeptide. The fraction specifically active against R. solani contained bacillomycin D C15 and 2 unknown lipopeptides. The 80% methanol fraction had a moderate and a broad spectrum activity against the two pathogens and consisted from two iturin D (C13 and C14) as a major lipopeptides. PMID:25272736

Elkahoui, S; Djébali, N; Karkouch, I; Ibrahim, A Hadj; Kalai, L; Bachkovel, S; Tabbene, O; Limam, F

2014-01-01

122

Dried powders of velvetbean and pine bark added to soil reduce Rhizoctonia solani-induced disease on soybean Pós secos de mucuna e casca de pinus adicionados ao solo reduzem a doença causada por Rhizoctonia solani em soja  

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Full Text Available Diseases induced by Rhizoctonia solani, like damping-off and root and stem rot on soybean (Glycine max, are a serious problem around the world. The addition of some organic material to soil is an alternative control for these diseases. In this study, benzaldehyde and dried powders of kudzu (Pueraria lobata, velvetbean or mucuna (Mucuna deeringiana, and pine bark (Pinus spp. were used in an attempt to improve soybean plant growth and to reduce the disease R. solani (AG-4 causes on soybean. Benzaldehyde (0.1-0.4 mL/kg of soil and velvetbean (25-100 g/kg significantly (P As doenças em soja (Glycine max causadas por Rhizoctonia solani são um sério problema ao redor do mundo. A incorporação ao solo de resíduos orgânicos é uma alternativa para o controle destas doenças. Neste estudo, benzaldeido e pós-secos de kudzu (Pueraria lobata, mucuna (Mucuna deeringiana e casca de pinus (Pinus spp. foram usados com o objetivo de melhorar o crescimento de plantas de soja e de diminuir a doença causada por R. solani (AG-4. Benzaldehyde (0,1-0,4 mL/kg de solo e mucuna (25-100 g/kg reduziram significativamente (P < 0.05 o crescimento micelial de R. solani em experimentos de laboratório. Em experimentos conduzidos em casa de vegetação a porcentagem de plantas sobreviventes foi maior em solo com casca de pinus e mucuna (50-100 g/kg. Em solo tratado com kudzu (r²=0,91 ou mucuna (r²=0,94, houve tendência significativa em aumentar a massa fresca das plantas de soja. Em microparcelas de campo solos com mucuna (r²=0,85 ou com casca de pinus (r²=0,61 reduziram significativamente a quantidade de doença. A quantidade de Bacillus megaterium (r²=0,87 e Trichoderma hamatum (r²=0,92 e a hidrólise de diacetato fluoresceina (r²=0,91 foram maiores em solo com doses crescentes de mucuna, indicando uma maior atividade microbiana. Neste estudo conclui-se que pós-secos de mucuna e casca de pinus, incorporados ao solo, podem reduzir a doença causada por R. solani em soja.

Luiz E. B. Blum

2006-06-01

123

Técnica de inoculación rápida y eficiente para la evaluación de materiales de maíz (zea mays l.) ante rhizoctonia solani kuhn / Efficient and fast inoculation technique for evaluation of maize germplasms (Zea mays L.) for resistance to Rhizoctonia solani Kuhn  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish Para la búsqueda de germoplasmas de maíz resistentes a Rhizoctonia solani es necesario realizar pruebas de inoculación para determinar su comportamiento. Para ello se requiere de una técnica de inoculación que proporcione una respuesta rápida, efectiva y confiable en la manifestación de la enfermeda [...] d, y que sea de fácil y práctica aplicación a una gran población de plantas y materiales genéticos. Con este fin se realizaron pruebas en el Posgrado de Agronomía de la Universidad Centroccidental "Lisandro Alvarado", en Tarabana, estado Lara, Venezuela, y en las instalaciones de la Fundación DANAC, San Javier, estado Yaracuy, con plantas de maíz de 15 días de edad, desarrolladas en vivero. Se utilizaron las siguientes ocho técnicas: inoculación a la semilla, siembra en suelo inoculado con una de las siguientes tres formas: hojas de maíz infectadas, esclerocios o granos de arroz infectados y aplicación sobre plantas de maíz de una de las siguientes cuatro formas: esclerocios, granos de arroz infectados, trocitos de hojas de maíz infectados o micelio sobre el ápice de plantas de 15 días de edad La cepa de R. solani fue aislada de la localidad El Playón, estado Portuguesa. La técnica más adecuada resultó ser la utilización de granos de arroz infectados aplicados al momento de la siembra (incidencia 100%), aunque la utilización de esclerocios de R. solani también resultó eficiente, pero menos práctica su aplicación; la inoculación a la semilla de maíz fue eficiente, pero presentó el menor tamaño de mancha. Para inoculaciones al follaje, el tratamiento con mayor incidencia en plantas (100%) fue el de granos de arroz; la aplicación de micelio produjo una respuesta más rápida y mayor tamaño de mancha (9,43 cm). La técnica más segura y factible para la inoculación de Rhizoctonia solani en plantas de maíz de 15 días de edad la constituyó la de granos de arroz infectados con el patógeno por su facilidad de aplicación y de multiplicación del inóculo. Abstract in english In search of resistance to Rhizoctonia solani in maize germplasms, it is necessary to make inoculation tests to determine its behavior. Inoculation techniques that provide fast, effective, and reliable responses in the manifestation of the disease and also of easy and practical application to a wide [...] population of plants and genetic materials are required. Tests were conducted at UCLA, Posgrado de Agronomia in Tarabana, Lara state, Venezuela and in the facilities of DANAC Foundation in San Javier, Yaracuy state, utilizing 15 days old maize plants, developed under nursery conditions. Eight techniques were tested, among them seed inoculation, sowing in soil inoculated with infected mayze leaves or infected rice grains or esclerotia, application of esclerotia, micelia, infected mayze leaves or infected rice grains on the apex of 15 days old plants. R. solani stock was isolated from the locality of El Playón- Portuguesa state. The most practical and reliable technique was the use of infected rice grains at the time of sowing (incidence 100 %), although the use of R. solani esclerotia also was efficient, but less practical its application; the inoculation to the maize seed was efficient, but it showed to be of minor size the lesions. In foliage inoculation, the treatment with more incidences in plants (100 %) also was the one of rice kernels. The application of micelia alone, gave a fast response and large size of lesions (9.43 cm). The more surely and feasible technique for R. solani inoculation in 15 days old maize plants, by its facility of application and inocula multiplication, it constituted the rice grains infected with the pathogen.

Juan, Pineda; Alexander, Hernández; Alex, González; Venancio, Barrientos; Herman, Nass; Elizabeth, Gil.

2005-04-01

124

Rhizoctonia solani Kühn aislado de papa (Solanum tuberosum L.): En los estados Táchira, Mérida, Trujillo y Lara. I. Caracterización cultural / Rhizoctonia solani Kühn isolated from potato (Solanum tuberosum L.): in Táchira, Mérida, Trujillo and Lara States, Venezuela. I. Cultural characterization  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish La papa es uno de los rubros más importantes en la economía de Venezuela. Este cultivo se ve afectado por diferentes patógenos, uno de ellos es el hongo Rhizoctonia solani, que ocasiona la rizoctoniosis, enfermedad que está ampliamente distribuida en el país y es la causa de pérdidas económicas cons [...] iderables. Con la finalidad de comparar las poblaciones del hongo en Venezuela, se llevó a cabo el trabajo; para ello se colectaron muestras en diferentes zonas productoras de papa de los estados Táchira, Mérida, Trujillo, y Lara. El patógeno fue caracterizado culturalmente mediante el estudio de su condición nuclear y determinación del grupo de anastomosis (AG), así como la evaluación del desarrollo micelial, número y diámetro de esclerocios, a 10, 20 y 30 °C. Se encontraron diferencias significativas (P?0,01) en cuanto a las características culturales de las cepas evaluadas, las cuales mostraron mejor comportamiento en su desarrollo a 20 °C; se determinó que 97,5 % de las cepas fueron AG-3 y 2,5 % AG-2.1. Los resultados indicaron diferencias culturales entre las poblaciones de R. solani analizadas lo que puede estar asociado con el comportamiento de la enfermedad en las diferentes localidades. Abstract in english Potato is one of the most important crops in Venezuelan economy. This crop is affected by different pathogens, one of which is the fungus Rhizoctonia solani, the inducer of rhizoctonia disease; which is widely distributed and is the cause of considerable economic losses. In order to know phenotypic [...] variation among fungus populations, this research was carried out with samples collected at different potato producing areas of Táchira, Merida, Trujillo, and Lara States. The pathogen was culturally characterized by the study and determination of its nuclear condition, anastomosis group (AG), as well as colony growth, and number and diameter of sclerotia at 10, 20 and 30 °C. Significant differences (P?0.01) were found among strains with regard to the cultural characteristics; in general, strains showed better behavior of their development at 20 °C; 97.5 % of the strains were found to be AG-3 and the other 2.5 %, AG-2.1. Results indicated differences in cultural characteristics among the R. solani populations, which may be associated with disease behavior at the different localities.

Yoleidy, Escalona; Dorian, Rodríguez; Alexander, Hernández.

125

An immunological approach to quantifying the saprotrophic growth dynamics of Trichoderma species during antagonistic interactions with Rhizoctonia solani in a soil-less mix.  

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Studies of the saprotrophic growth dynamics of Trichoderma species and their fungal hosts during antagonistic interactions are severely hampered by the absence of methods that allow the unambiguous identification and quantification of individual genera in complex environments such as soil or compost containing mixed populations of fungi. Furthermore, methods are required that allow discrimination between active hyphal growth and other components of fungal biomass such as quiescent spores that are produced in large numbers by Trichoderma species. This study details the use of monoclonal antibodies to quantify the saprotrophic growth dynamics of the soil-borne plant pathogen Rhizoctonia solani and biological control strains of Trichoderma asperellum and Trichoderma harzianum during antagonistic interactions in peat-based microcosms. Quantification was based on the immunological detection of constitutive, extracellular antigens that are secreted from the growing tip of Rhizoctonia and Trichoderma mycelium and, in the case of Trichoderma harzianum, from quiescent phialoconidia also. The Trichoderma-specific monoclonal antibody (MF2) binds to a protein epitope of the enzyme glucoamylase, which was shown by immunofluorescence and immunogold electron gold microscopy studies of Trichoderma virens in vitro to be produced at the origin of germ tube emergence in phialoconidia and from the growing tip of germ tubes. In addition, a non-destructive immunoblotting technique showed that the enzyme was secreted during active growth of Trichoderma asperellum mycelium in peat. The Rhizoctonia solani-specific monoclonal antibody (EH2) similarly binds to a protein epitope of a glycoprotein that is secreted during active mycelial growth. Extracts derived from lyophilized mycelium were used as a quantifiable and repeatable source of antigens for construction of calibration curves. These curves were used to convert the absorbance values obtained in ELISA tests of peat extracts to biomass equivalents, which allowed comparisons of the saprotrophic growth dynamics of the pathogen and antagonists to be made in single or mixed species microcosms. Trichoderma species were able to compete successfully with R. solani for nutrients and to prevent saprotrophic growth of the pathogen. Specificity of the Trichoderma quantitative assay was tested in non-sterile soil-based microcosms artificially inoculated with T. asperellum. The assay was highly specific and only detected T. asperellum population dynamics. No cross-reactivity was found with extracts from soil samples containing contaminant fungi. PMID:15008811

Thornton, Christopher R

2004-04-01

126

Estudio de Rhizoctonia solani Kühn aislado de papa (Solanum tuberosum L.) en los estados Táchira, Mérida, Trujillo y Lara: II. virulencia y caracterización molecular / Rhizoctonia solani Kühn isolated from potato in various Venezuelan states: II. Virulence and molecular characterization  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish Rhizoctonia solani ocasiona la enfermedad conocida como rizoctoniosis en el cultivo de la papa y constituye un serio problema en Venezuela. En el país se han identificado los grupos anastomósicos presentes y se ha realizado la caracterización cultural del hongo pero no la molecular ni la de virulenc [...] ia, por lo que estos objetivos fueron planteados en el presente trabajo. Se utilizaron cuarenta aislamientos obtenidos de los estados Táchira, Mérida, Trujillo y Lara. Se utilizaron las técnicas de RAPD, UPR e ITS para la caracterización molecular, y pruebas de patogenicidad en papa ‘Kennebec’ para determinar la virulencia. Con las tres técnicas moleculares se observaron variaciones genéticas entre las cepas del hongo y se confirmó la presencia de AG-3 y AG-2.1 de R. solani. Las cepas mostraron diferencias significativas en la virulencia, la cual estuvo influenciada por la temperatura. Abstract in english Rhizoctonia solani causes the disease known as rizoctoniosis in potato and it is a serious problem in Venezuela. Anastomosis groups and cultural characterization have been determined in the country, but neither molecular nor virulence characterization. Therefore, the research focused on those two ob [...] jectives. Forty isolates from Táchira, Merida, Trujillo and Lara States were used on which RAPD, UPR and ITS techniques were performed; also, pathogenicity tests were run on ‘Kennebec’ potato plants. Genetic variability among isolates was observed with all three molecular techniques and presence of AG-3 and AG-2.1 was confirmed. Isolates showed significant difference with regard to virulence, which was influenced by temperature.

Yoleidy, Escalona; Dorian, Rodríguez; Alexander, Hernández.

127

Solarização do solo em casa-de-vegetação e campo para o controle de Rhizoctonia solani AG-4 / Soil solarization under greenhouse and field conditions to the control of Rhizoctonia solani AG-4  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os cultivos em ambientes protegidos apresentaram uma grande expansão na década de 1990 no Brasil. O solo desses locais pode, por ser intensa e sucessivamente cultivado, se tornar infestado por patógenos como Rhizoctonia solani, responsável por tombamento e podridão de raízes em muitas espécies de pl [...] antas. O presente trabalho avaliou o emprego da solarização, dentro e fora de uma casa-de-vegetação vedada com plástico transparente, para o controle de R. solani. Quatro experimentos foram realizados, dois no verão de 1997/1998 e outros dois no verão seguinte, 1998/1999, em Piracicaba, SP (latitude 22º 42' e longitude 47º 38'). Bolsas de náilon contendo solo autoclavado misturado a grãos de trigo colonizados com R. solani AG-4 foram enterradas a 10 e a 20 cm de profundidade em parcelas solarizadas e não solarizadas, dentro e fora da casa-de-vegetação, sendo coletadas após 20, 30 e 40 dias para os dois primeiros experimentos e 15, 30 e 45 dias para o terceiro e quarto. Avaliou-se a viabilidade do patógeno após a recuperação dos grãos dos solos, por meio do plaqueamento destes em ágar-água, contando-se, dois dias depois, sob microscópio estereoscópio, os que apresentaram crescimento micelial característico de R. solani. Foi obtida a erradicação do patógeno após 20 e 30 dias de solarização na casa de vegetação e após 30 a 45 dias no campo, provavelmente porque houve menor perda de calor durante a noite no ambiente protegido, pois as temperaturas médias (40 a 45 º C, dependendo do experimento) e máxima (49º C) dos solos solarizados às 15:00 horas, a 10 cm de profundidade, foram semelhantes nos dois ambientes. Nas parcelas não solarizadas da casa-de-vegetação o patógeno também perdeu a viabilidade, porém mais lentamente (40 dias de tratamento para sua erradicação) que nas parcelas solarizadas. Abstract in english Crops grown under protected environment have had a great expansion in Brazil in the decade of 1990. In such environments soil is intensively and successively used and it may become infested with soilborne plant pathogens, such as Rhizoctonia solani, responsible for seedling damping-off and root rots [...] of several plant species. In the present work soil solarization was used to the control of R. solani under greenhouse and field conditions. Four experiments were carried out, two in the summer of 1997/1998 and the other two in 1998/1999 in Piracicaba city, São Paulo state, Brazil (latitude 22º 42' and longitude 47º 38'). Nylon bags containing disinfested soil with propagules of R. solani AG4 (wheat grains previously colonized with the pathogen) were buried at 10 and 20 cm soil depth in solarized and non-solarized plots. After 20, 30, and 40 days in the two first experiments and 15, 30, and 45 days in the third and fourth experiments, the bags were removed from the soil. The grains were collected from the soil of each bag and placed in water-agar Petri dishes. After two days of incubation, grains showing typical growth of R. solani mycelium were assessed. Eradication of R. solani was accomplished after 20 to 30 days of soil solarization inside the greenhouse and after 30 to 45 days in the field, probably because in the protected environment the heat loss was smaller at night, since at 15:00 h the soil temperatures were similar in the solarized soils of both environments; with maximum of 49º C and medium temperatures between 40 and 45 º C, at 10 cm soil depth. In the non-solarized soil of the greenhouse the pathogen also lost its viability, although more slowly (40 days of treatment) than in the solarized plots.

Flávia Rodrigues Alves, Patrício; Hiroshi, Kimati; João, Tessarioli Neto; Ademir, Petenatti; Benedito Camargo, Barros.

2007-09-01

128

Efeito do silicato de cálcio e da autoclavagem na supressividade e na conducividade de dois solos à Rhizoctonia solani Influence of calcium silicate and sterilization on the natural suppressiveness and on the conduciveness of two soils to Rhizoctonia solani  

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Full Text Available Objetivou-se verificar o efeito da aplicação de silicato de cálcio e da esterilização na supressividade natural de um Latossolo Vermelho-Escuro (LEa álico textura muito argilosa e na conducividade natural de uma Terra Roxa Estruturada eutrófica (TRe ao fungo Rhizoctonia solani, em condições de casa de vegetação. Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 2 x 3 x 2. Os fatores foram: duas classes de solo (LEa e TRe - 0-20 cm; três tratamentos (esterilização ou não por autoclavagem, aplicação de silicato e testemunha e infestação ou não com R. solani, com três repetições e 16 plântulas de feijoeiro por parcela. A aplicação de silicato foi feita incorporando 0,63 g do produto em 1 kg de cada material de solo, seguido de incubação por 30 dias. Para promover a infestação artificial, foram colocados 800 mg de inóculo em 1 kg de cada material de solo. O silicato de cálcio aumentou os teores de Ca trocável e a soma de bases nos dois solos. Um decréscimo na saturação por Al de 70 para 19% e um aumento na saturação por bases de 9 para 21% alteraram significativamente a supressividade natural do LEa à R. solani. Com relação à TRe, a aplicação de silicato não teve nenhum efeito na sua conducividade, dado ao seu natural caráter eutrófico, o qual já é favorável ao desenvolvimento deste fungo. A esterilização não influiu no desenvolvimento de R. solani, o que sugere que os fatores abióticos foram os responsáveis pela supressividade ou conducividade desses solos.The effect of calcium silicate slag and soil sterilization on the natural suppressiveness of a Typic Acrustox (clay Dark Red Latosol -- LEa and the natural conduciveness of an Oxic Haplustoll (TRe to Rhizoctonia solani were studied under greenhouse conditions. The experimental design was a three-replicate completely randomized one, with 2 x 3 x 2 factorial combination of the following treatments: two soil kinds (LEa and TRe, collected at 0-20 cm layer; three treatments with and without soil sterilization, calcium silicate slag and nontreated control; and uninfested and infested with R. solani. Each soil material was infested previously with 800 mg of the inoculum per kg soil. Application of silicate was done mixing 0,63 g of this product with 1 kg each soil material and incubated for 30 days. The application ofsilicate increased the exchangeable Ca2+ and bases amount in both soils. The decrease in the aluminum saturation level from 70 to 19% and the increase in base saturation from 9 to 21% altered significantly the natural suppressiveness of LEa to R. solani. Application of silicate to the TRe had no effect on its conduciveness, for its natural eutrophic character, which is benefic to R. solani development. Sterilization by autoclavation did not influence disease development on bean by R. solani. This suggests that possibly other abiotic factors were responsible for either suppressiveness or conduciveness of these soils.

Fabrício de Ávila Rodrigues

1999-08-01

129

Solarização do solo em casa-de-vegetação e campo para o controle de Rhizoctonia solani AG-4 Soil solarization under greenhouse and field conditions to the control of Rhizoctonia solani AG-4  

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Full Text Available Os cultivos em ambientes protegidos apresentaram uma grande expansão na década de 1990 no Brasil. O solo desses locais pode, por ser intensa e sucessivamente cultivado, se tornar infestado por patógenos como Rhizoctonia solani, responsável por tombamento e podridão de raízes em muitas espécies de plantas. O presente trabalho avaliou o emprego da solarização, dentro e fora de uma casa-de-vegetação vedada com plástico transparente, para o controle de R. solani. Quatro experimentos foram realizados, dois no verão de 1997/1998 e outros dois no verão seguinte, 1998/1999, em Piracicaba, SP (latitude 22º 42' e longitude 47º 38'. Bolsas de náilon contendo solo autoclavado misturado a grãos de trigo colonizados com R. solani AG-4 foram enterradas a 10 e a 20 cm de profundidade em parcelas solarizadas e não solarizadas, dentro e fora da casa-de-vegetação, sendo coletadas após 20, 30 e 40 dias para os dois primeiros experimentos e 15, 30 e 45 dias para o terceiro e quarto. Avaliou-se a viabilidade do patógeno após a recuperação dos grãos dos solos, por meio do plaqueamento destes em ágar-água, contando-se, dois dias depois, sob microscópio estereoscópio, os que apresentaram crescimento micelial característico de R. solani. Foi obtida a erradicação do patógeno após 20 e 30 dias de solarização na casa de vegetação e após 30 a 45 dias no campo, provavelmente porque houve menor perda de calor durante a noite no ambiente protegido, pois as temperaturas médias (40 a 45 º C, dependendo do experimento e máxima (49º C dos solos solarizados às 15:00 horas, a 10 cm de profundidade, foram semelhantes nos dois ambientes. Nas parcelas não solarizadas da casa-de-vegetação o patógeno também perdeu a viabilidade, porém mais lentamente (40 dias de tratamento para sua erradicação que nas parcelas solarizadas.Crops grown under protected environment have had a great expansion in Brazil in the decade of 1990. In such environments soil is intensively and successively used and it may become infested with soilborne plant pathogens, such as Rhizoctonia solani, responsible for seedling damping-off and root rots of several plant species. In the present work soil solarization was used to the control of R. solani under greenhouse and field conditions. Four experiments were carried out, two in the summer of 1997/1998 and the other two in 1998/1999 in Piracicaba city, São Paulo state, Brazil (latitude 22º 42' and longitude 47º 38'. Nylon bags containing disinfested soil with propagules of R. solani AG4 (wheat grains previously colonized with the pathogen were buried at 10 and 20 cm soil depth in solarized and non-solarized plots. After 20, 30, and 40 days in the two first experiments and 15, 30, and 45 days in the third and fourth experiments, the bags were removed from the soil. The grains were collected from the soil of each bag and placed in water-agar Petri dishes. After two days of incubation, grains showing typical growth of R. solani mycelium were assessed. Eradication of R. solani was accomplished after 20 to 30 days of soil solarization inside the greenhouse and after 30 to 45 days in the field, probably because in the protected environment the heat loss was smaller at night, since at 15:00 h the soil temperatures were similar in the solarized soils of both environments; with maximum of 49º C and medium temperatures between 40 and 45 º C, at 10 cm soil depth. In the non-solarized soil of the greenhouse the pathogen also lost its viability, although more slowly (40 days of treatment than in the solarized plots.

Flávia Rodrigues Alves Patrício

2007-09-01

130

Micoflora asociada a dos sustratos orgánicos y su efecto en el control de Rhizoctonia solani Kühn / Mycoflora of two organic substrates and its effect on the control of Rhizoctonia solani Kühn  

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Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Los abonos orgánicos se vienen utilizando como ente supresor de enfermedades de la raíz de la planta, debido a la gran cantidad de microorganismos que interactúan en ellos, lo que ha llevado a considerarlos como parte de las estrategias de control biológico. En este contexto, se evaluó la diversidad [...] de la micoflora de dos sustratos orgánicos (suelo orgánico y lombricompuesto) y su efecto sobre el control del hongo Rhizoctonia solani. La diversidad de la micoflora de los sustratos se determinó a través del método de dilución de placas de Warcup, que permitió contar el número de colonias e identificar los hongos. Los aislamientos más abundantes de cada sustrato fueron seleccionados para realizar cultivos duales con Rhizoctonia solani. Se encontraron 16 aislamientos de hongos pertenecientes a tres ordenes y ocho géneros, incluyendo (Penicillium sp., Aspergillus sp., Fusarium sp. y Trichoderma harzianum Rifai). En el lombricompuesto se encontró una micoflora significativamente más abundante (P?0,05) que en el suelo orgánico. En los cultivos duales, T. harzianum presentó un porcentaje de inhibición de R. solani significativamente superior (P?0,05) al del resto de los hongos. Con la incorporación del lombricompuesto no se introdujeron nuevos hongos, pero sí se incrementaron las poblaciones existentes en la micoflora nativa. T. harzianum resultó ser el hongo de mayor crecimiento y mayor porcentaje de inhibición, lo que sugiere que es un controlador biológico de R. solani, y que es factible incorporarlo al suelo durante la preparación del mismo. Abstract in english The use of organic manures for root disease control, which results from the remarkable diversity of microorganisms that interact there, has led to consider them as part of biological control strategies. In this context, we evaluated the mycological diversity of two organic substrates, (organic soil [...] and vermicompost) and their effect on the control of the fungus Rhizoctonia solani. The mycoflora of the two organic substrates was assessed through Warcup's soil plate method, which allowed identifying the fungi and counting the number of colonies. The most abundant isolates were grown against R. solani in dual cultures. The results allowed identifying 16 isolates belonging to three orders and eight genera of fungi, including Penicillium sp., Aspergillus sp., Fusarium sp. and Trichoderma harzianum Rifai. A significantly more abundant mycoflora (P?0.05) was found in the vermicompost substrate. In the dual cultures, T. harzianum attained a higher pathogen inhibition percentage (P?0.05) than the other fungi. The vermicompost substrate did not determine the growth of new fungi, but enhanced the development of the pre-existing native ones. Not only having shown the best results in controlling R. solani, but also the most vigorous growth among the identified fungi, T. harzianum comes up as a promissory biological controller of the pathogen, that can be incorporated to the soil during its preparation.

Clemencia, Guédez; Luis Miguel, Cañizalez; Carmen, Castillo; Rafael, Olivar.

2009-12-01

131

Essential oil of mustard to control Rhizoctonia solani causing seedling damping off and seedling blight in nursery / Utilização de óleo essencial de mostarda no controle de tombamento e requeima causadas por Rhizoctonia solani em viveiro  

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese Foi avaliado o efeito do óleo essencial extraído de sementes de mostarda (Brassica rapa) na supressão do crescimento in vitro de Rhizoctonia solani, na redução da colonização saprofítica no solo, e no tombamento e requeima de plântulas, utilizando feijão-vagem (Phaseolus vulgaris) como planta indica [...] dora. O crescimento in vitro de R. solani foi completamente inibido na concentração de 50 mil/l. A colonização saprofítica do substrato foi drasticamente reduzida para 45% na concentração de 150 mil/kg, 24 h após o tratamento. Nas concentrações de 0, 50 e 75 mil/kg de solo houve 100% de colonização do substrato. Esta taxa de recuperação diminuiu gradualmente para 6% e 60%, respectivamente, em nove dias. A irrigação de solos infestados por R. solani com água contendo o óleo essencial emulsificado para fornecer 150 mil/l de solo, dez dias antes do plantio, resultou em 95% de controle do tombamento e requeima em mudas de feijão-vagem, sem qualquer efeito aparente de fitotoxidez. O efeito do óleo essencial não foi influenciado pela textura do solo e parece ser um bom substituto para o fumigante brometo de metila em viveiros. Abstract in english The essential oil extracted from mustard (Brassica rapa) seeds was evaluated for its effect on suppression of Rhizoctonia solani growth in vitro, and in field soils, for reducing saprophytic substrate colonization and seedling damping off and blight using snap beans as indicator plant, the in vitro [...] growth was completely inhibited at a concentration of 50 mul/l. The saprophytic substrate colonization in soils 24 h after treatment was drastically reduced to 45% at 150 mul/kg soil concentration, in contrast to 100% colonization at concentrations of 0, 50, or 75 mul/kg. This recovery rate gradually declined to 6% and 60%, respectively, in nine days. A control of pre and post-emergence seedling damping off and blight in common beans (Phaseolus vulgaris), without any apparent phytotoxic effect was achieved by irrigating R. solani infested soils with water containing the emulsified essential oil to provide 150 mul/l soil volume ten days prior to planting, gave over 95%. The effect of the mustard essential oil was not influenced by the physical soil texture, and it appears to be a good substitute for methyl bromide fumigation in nurseries for seedling production.

Onkar D., Dhingra; Maria L. N., Costa; Geraldo J., Silva, Jr.; Eduardo S. G., Mizubuti.

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Biological Control of Rhizoctonia solani, the Causal Agent of Rice Sheath Blight by Antagonistics Bacteria in Greenhouse and Field Conditions  

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Full Text Available Pseudomonas fluorescens isolates that inhibited growth of Rhizoctonia solani Kühn, the rice sheath blight pathogen were collected the rhizosplane and surrounding soil of healthy and rice sheath blight disease in farming of the Guilan province, Iran. Two hundred eighty eight isolates tested and among them only antagonistic ability of 8 isolates were demonstrated by using the dual culture method. According to the results of biochemical and morphological trials all isolates were identified as P. fluorescens biovar 3. By determining the effects of volatile metabolites, secretion of extracellular and antibiotics of these isolates inhibited mycelial growth of R. solani in vitro. All P. fluorescens isolates produced siderophore on King`s medium B, inhibited the mycelial growth of the R. solani. Antagonistics isolates reduced the germination and cause the lysis of sclerotia of R. solani. In greenhouse conditions antagonistic isolates were used by seed coating, soil drenching and foliar spray. Statistical analysis of data indicated that there existed significant differences between seed, soil and plant treatments. All of the isolates in seed coating are more effective. In the field conditions foliar spray of isolate B41 mixed with benlate were applied. The disease intensity in B41 isolate for seed coating, soil drenching and seed coating + foliar spray were 10.5, 11.75 and 18.75%, respectively, while the control plants showed 52% disease intensity. These results suggest that the P. fluorescens isolates studied have an excellent potential to be used as biocontrol agents of R. solani in rice at the field conditions.

Mostapha Niknejad Kazempour

2004-01-01

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Genome Sequence of Bacillus subtilis MB73/2, a Soil Isolate Inhibiting the Growth of Plant Pathogens Dickeya spp. and Rhizoctonia solani  

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Bacillus subilis MB73/2 is a Gram-positive bacterium isolated in Poland from a meadow soil sample. When tested in vitro, the strain shows strong antagonism toward plant pathogens—the soft rot-causing bacteria Dickeya spp. and the crown rot fungus Rhizoctonia solani. Here, we present the genome sequence of MB73/2.

Krzyzanowska, Dorota M.; Iwanicki, Adam; Ossowicki, Adam; Obuchowski, Micha?; Jafra, Sylwia

2013-01-01

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Effects of fescue Festuca arundinacea and/or clover Trifolium repens debris and fescue leaf leachate on clover as modified by ozone and Rhizoctonia solani  

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Clover Trifolium repens and tall fescue Festuca arundinacea plants were exposed to ozone and inoculated with Rhizoctonia solani separately and in combination to investigate ozone/R. solani interactions on clover and tall fescue biomass, in the presence of clover and/or tall fescue debris or fescue leaf leachate. Ozone reduced biomass in clover. Rhizoctonia solani alone reduced clover biomass but the amount of this reduction was significantly greater in the presence of a single acute O/sub 3/ exposure. In the presence of multiple O/sub 3/ exposures the synergistic effect on clover biomass disappeared and the stress from R. solani was lost. The effects of O/sub 3/ and R. solani were not as pronounced on fescue as they were on clover. The debris treatments increased biomass of both clover and fescue, but the magnitude of change depended on the debris type. Leachate from fescue modified the effects of R. solani and O/sub 3/, but debris from clover and/or fescue did not. Clover plants treated with R. solani and O/sub 3/ had less biomass than control plants when stressed by leachate from fescue, but significantly greater biomass in the presence of leachate from O/sub 3/-treated fescue leaves.

Kochhar, M.; Reinert, R.A.; Blum, U.

1982-08-01

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INDUCED SUPPRESSIVENESS TO Rhizoctonia solani KÜHN BY THE ADDITION OF DIFFERENT VEGETABLE AMENDMENTS TO THE SOIL SUPRESSIVIDADE INDUZIDA A Rhizoctonia solani Kühn PELA ADIÇÃO DE DIFERENTES RESÍDUOS VEGETAIS AO SOLO  

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Organic matter of several origins is used in the agriculture to stimulate microbial activity and to limit the activity of plant pathogens. Its decomposition induces the activity of some microorganisms that are useful to other species establishing synergistic and antagonistic relationships that maintain the biological balance. The present work aimed to evaluate the effect of different vegetable amendments incorporated in the soil on the incidence of root-rot, caused by Rhizoctonia solani. In greenhouse, plastic trays containing 4 kg of cultivated soil were inoculated with 104 propagules of Rhizoctonia solani g-1 of soil and in each tray it was incorporated the equivalent of 10 t/ha plant of debris mater of the following species: Panicum miliaceum, Sorghum maximum, Dolichos lab-lab, Canavaria ensiformis, Braquiaria brizanta, Panicum maximum and Crotalaria juncea. The incorporation of the vegetable amendments were realized simultaneous by and the soil was maintained near field capacity for 60, 30 and 0 days, before the bean cultivar Pérola was sown. Symptom intensity was evaluated 15 days after the emergence, using a descriptive scale, varying from 0 to 8. After the completion of the experimental microbial population was estimated in the soil samples collected
from each plastic tray serial dilution test using selective culture media. Bacteria and fungi colonies were counted after a seven days incubation period and those of actinomycetes after ten days. Results showed that only vegetable materials incubated for 60 days were able to reduce disease index. No significant differences were observed among the studied plant species. The relationship among number of propagules of fungi, actinomycetes, and bacteria with the disease index revealed that the amendments with a larger induced microbial population in the soil were those that presented smaller disease index.

KEY-WORDS: Rhizoctonia root rot; biological control; soil microbial population.

A matéria orgânica de diversas origens é utilizada na agricultura visando, entre outras finalidades, a estimular a atividade microbiana para limitar a atividade dos patógenos do solo. Sua decomposição induz a atividade de alguns organismos, que se tornam úteis a outros tipos de vida, e estabelece relações sintróficas e antagônicas que mantêm o equilíbrio da comunidade biológica como um todo. O presente trabalho teve como objetivo avaliar o efeito da incorporação de diferentes restos vegetais na incidência de podridão radicular do feijoeiro, cujo agente causal é o fungo Rhizoctonia solani. Em casa-de-vegetação, foram utilizadas bandejas plásticas contendo 4 kg de solo cultivado, inoculado com 104 propágulos de Rhizoctonia solani g-1, ao qual foi incorporado o equivalente a 10 t/ha de matéria seca das seguintes origens: Panicum miliaceum, Sorghum maximum, Dolichos lab-lab, Canavaria ensiformis, Braquiaria brizanta, Panicum maximum e Crotalaria juncea. A incorporação do inóculo e dos resíduos vegetais no solo foi realizada simultaneamente. O solo, nas bandejas, foi mantido próximo da capacidade de campo por 60, 30 e 0 dias, antes de ser realizada a semeadura da cu

Wilson Mozena Leandro

2007-09-01

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Suppression of Rhizoctonia solani on Impatiens by Enhanced Microbial Activity in Composted Swine Waste-Amended Potting Mixes.  

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ABSTRACT Peat moss-based potting mix was amended with either of two composted swine wastes, CSW1 and CSW2, at rates from 4 to 20% (vol/vol) to evaluate suppression of pre-emergence damping-off of impatiens (Impatiens balsamina) caused by Rhizoctonia solani (anastomosis group-4). A cucumber bioassay was used prior to each impatiens experiment to monitor maturity of compost as the compost aged in a curing pile by evaluating disease suppression toward both Pythium ultimum and R. solani. At 16, 24, 32, and 37 weeks after composting, plug trays filled with compost-amended potting mix were seeded with impatiens and infested with R. solani to determine suppression of damping-off. Pre-emergence damping-off was lower for impatiens grown in potting mix amended with 20% CSW1 than in CSW2-amended and nonamended mixes. To identify relationships between disease suppression and microbial parameters, samples of mixes were collected to determine microbial activity, biomass carbon and nitrogen, functional diversity, and population density. Higher rates of microbial activity were observed with increasing rates of CSW1 amendment than with CSW2 amendments. Microbial biomass carbon and nitrogen also were higher in CSW1-amended mixes than in CSW2-amended potting mixes 1 day prior to seeding and 5 weeks after seeding. Principal component analysis of Biolog-GN2 profiles showed different functional diversities between CSW1- and CSW2-amended mixes. Furthermore, mixes amended with CSW1 had higher colony forming units of fungi, endospore-forming bacteria, and oligotrophic bacteria. Our results suggest that enhanced microbial activity, functional and population diversity of stable compost-amended mix were associated with suppressiveness to Rhizoctonia damping-off in impatiens. PMID:18944095

Diab, H G; Hu, S; Benson, D M

2003-09-01

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Caracterización y evaluacion de virulencia en aislamientos de rhizoctonia solani kühn, causante de la mancha bandeada en maíz / Characterization and evaluation of virulence in rhizoctonia solani kühn isolates, causal agent of leaf banded spot on maize / Caracterização e avaliação de virulência em isolamentos de rhizoctonia solani kühn, causante da mancha bandeada no milho  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in portuguese Na Venezuela a mancha bandeada do milho, causada por Rhizoctonia solani Kühn, tem uma alta incidência e distribuição nas principais áreas de plantio de milho, causando diminuição do rendimento. Em 2004 foram conduzidos ensaios com o objetivo de caracterizar e avaliar a virulência de 25 isolamentos d [...] e R. solani. Para a caracterização se realizaram avaliações culturais, microscópicas e moleculares, estas últimas utilizando uma seqüência de amplificação específica da região espaçadora transcrita interna do DNA ribossomal (rDNA-ITS). Para a avaliação da virulência se realizaram provas de inoculação nas línhas de milho CML-254 e L-82201-22-1-1, tanto em laboratório, usando uma solução de cinetina (6- furfuril-amino-purina), como em estufa, inoculando plântulas. As provas de caracterização demonstraram que os isolamentos efetivamente correspondiam a R. solani, ainda quando houve diferenças na cor das colônias, crescimento micelial e tamanho de esclerócios, entre outras. A análise molecular demonstrou que os isolamentos pertencem ao grupo de anastomosis AG1-IA. Na prova de inoculação em laboratório os isolamentos G1SOM1 e P2TUR3 tiveram maior índice de virulência. Em estufa, os isolamentos mais virulentos foram B1TOR1, P2TUR6 e B2SAB1. A linha CML-254 mostrou o maior nível de resistência à enfermidade em ambas provas de virulência. Os resultados permitiram identificar e caracterizar isolamentos que podem ser utilizados em programas de melhoramento genético para a identificação de possíveis fontes de resistência e na avaliação do germoplasma melhorado. Abstract in spanish En Venezuela la mancha bandeada del maíz, causada por Rhizoctonia solani Kühn, tiene una alta incidencia y distribución en las principales zonas maiceras, causando disminución de los rendimientos. En 2004 se condujeron ensayos con el objetivo de caracterizar y evaluar la virulencia de 25 aislamiento [...] s de R. solani. Para la caracterización se realizaron evaluaciones culturales, microscópicas y moleculares, estas últimas utilizando una secuencia de amplificación específica de la transcrita región espaciadora interna del ADN ribosomal (rADN-ITS). Para la evaluación de la virulencia se realizaron pruebas de inoculación en las líneas de maíz CML-254 y L-82201-22-1-1, tanto en laboratorio, usando una solución de cinetina (6- furfuril-amino-purina), como en invernadero, inoculando plántulas. Las pruebas de caracterización demostraron que los aislamientos efectivamente correspondían a R. solani, aun cuando hubo diferencias en el color de las colonias, crecimiento micelial y tamaño de esclerocios, entre otras. El análisis molecular demostró que los aislamientos pertenecen al grupo de anastomosis AG1-IA. En la prueba de inoculación en laboratorio los aislamientos G1SOM1 y P2TUR3 tuvieron mayor índice de virulencia. En invernadero los aislamientos más virulentos fueron B1TOR1, P2TUR6 y B2SAB1. La línea CML-254 mostró el mayor nivel de resistencia a la enfermedad en ambas pruebas de virulencia. Los resultados permitieron identificar y caracterizar aislamientos que pueden ser utilizados en programas de mejoramiento genético para la identificación de posibles fuentes de resistencia y en la evaluación del germoplasma mejorado. Abstract in english In Venezuela, banded leaf spot caused by Rhizoctonia solani Kühn is a widely distributed disease in the most important maize growing areas, causing important yield losses. In 2004, experiments were conducted with the purpose of characterizing and evaluating the virulence of 25 isolates of R. solani. [...] Characterization tests were performed throughout cultural, microscopic, and molecular evaluations, the latter using a specific ribosomal internal transcribed spacer region (rADN-ITS). Virulence tests were performed on the maize inbred lines CML-254 y L-82201-22-1-1, both in the laboratory using KIN solution (6-furfurilaminopurine), and in a greenhouse inoculat

Rosaura, Perdomo; Alexander, Hernández; Alex, González; Juan, Pineda; Jesús, Alezones.

2007-01-01

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Encapsulamento de Trichoderma inhamatum para o controle biológico de Rhizoctonia solani na propagação clonal de Eucalyptus Encapsulation of Trichoderma inhamatum for the biological control of Rhizoctonia solani in clonal propagation of Eucalyptus  

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Full Text Available Testou-se um novo sistema para o encapsulamento de Trichoderma inhamatum em grânulos de alginato de sódio, visando o controle biológico de Rhizoctonia solani, agente etiológico da mela de estacas/miniestacas de Eucalyptus spp. para enraizamento. No novo sistema idealizado, foi utilizado um aparato simples capaz de substituir eficientemente o equipamento (Bomba Peristáltica anteriormente utilizado, sendo possível aumentar a produção de 594 grânulos/min para aproximadamente 6.734 grânulos/min. Com este novo sistema, um isolado de T. inhamatum (UFV – 03 foi encapsulado em grânulos contendo as fontes alimentares: farelo de trigo, palha de arroz, farelo de aveia, folhas de eucalipto ou farelo de milho na concentração de 50 g/l. Na segunda etapa, a melhor fonte alimentar foi testada nas concentrações de 0 a 60 g/l. Os grânulos foram veiculados em substrato de enraizamento de eucalipto na concentração de 2% (p/p inoculado com micélio triturado de R. solani (2 mg/g de substrato e a atividade saprofítica do patógeno foi quantificada por meio do método de iscas. Posteriormente, os grânulos produzidos com a fonte alimentar e concentração que promoveram maior inibição do desenvolvimento de R. solani foram utilizados para determinar o tempo mínimo de pré-incubação e competição para supressão do patógeno, com a mesma metodologia. Observou-se aumento da supressão da atividade saprofítica de R. solani ao acréscimo de uma fonte alimentar. Daquelas testadas, farelo de trigo foi a melhor. Além disso, houve interação significativa e positiva ao aumento de sua concentração na formulação.A new system of encapsulating Trichoderma inhamatum in sodium alginate was developed for controlling Rhizoctonia solani blight of Eucalyptus spp. cuttings/mini-cuttings used for rooting. In this system, simpler materials and apparatus efficiently replaced the peristaltic pump, increasing pellet production from 594 pellets/min to approximately 6,734 pellet/min. An isolate of T. inhamatum (UFV-3 was encapsulated in pellets containing wheat bran, rice husk, oat bran, eucalyptus leaf or maize meal as food base at a concentration of 50g/l. In the second step, the best food base was evaluated at the concentrations ranging from 0 to 60 g/l. The pellets were added to R. solani infested (2 mg-macerated mycelium/g eucalyptus rooting substrate at the rate of 2% (w/w and the saprophytic activity of the pathogen was quantified with a baiting technique. The pellets containing wheat bran, which maximally inhibited R. solani, were used to determine the minimum pre-incubation and competition period for pathogen suppression. Increasing food base concentration in the pellets increased suppression of R. solani. Additionally, there was a significant positive interaction between food base concentration in the formulation and pathogen suppression.

Reginaldo G. Mafia

2003-01-01

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Efeito do silício nas concentrações de lignina e de açúcares em bainhas de folhas de arroz infectadas por Rhizoctonia solani / Effect of silicon on lignin and sugar concentrations of leaf sheaths in rice plants infected by Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A queima das bainhas, causada pelo fungo Rhizoctonia solani Kühn, é uma das mais importantes doenças que afetam a produção de arroz no mundo. Este trabalho teve como objetivo verificar o efeito do silício (Si) nas concentrações de lignina solúvel e insolúvel e de açúcares totais em bainhas de folhas [...] de arroz infectadas por R. solani. Plantas de arroz dos cultivares BR-Irga-409 e Labelle foram cultivadas em solução nutritiva sem (0 mM) ou com (2 mM) Si. A concentração de Si nas bainhas das folhas das plantas dos cultivares BR-Irga-409 e Labelle supridas com Si aumentou em 77% e 84%, respectivamente, em relação às plantas não supridas com Si. O comprimento relativo da lesão de queima das bainhas foi significativamente menor nas bainhas das plantas supridas com Si em relação às bainhas das plantas não supridas com esse elemento. Não houve efeito do Si e nem da inoculação com R. solani nas concentrações de mananas, galactanas, arabinanas, xilanas, glucanas e de açúcares totais nas bainhas das plantas dos dois cultivares. Para as plantas dos dois cultivares supridas com Si, a concentração de açúcares totais foi menor quando comparada com a dos dois cultivares na ausência de Si. Não houve variação na concentração de lignina insolúvel, solúvel e total entre os cultivares. As concentrações de lignina insolúvel e total foram maiores nas plantas supridas com Si, independentemente da inoculação com R. solani. Em conclusão, plantas de arroz supridas com Si foram mais resistentes à queima das bainhas devido a uma maior lignificação dos tecidos das bainhas e menor concentração de açúcares totais. Abstract in english Sheath blight, caused by the fungus Rhizoctonia solani Kühn, is the major disease affecting rice production worldwide. This study aimed to verify the effect of silicon (Si) on the concentrations of soluble and insoluble lignin and sugars in the leaf sheaths of rice plants infected by R. solani. Rice [...] plants from cultivars BR-Irga-409 and Labelle were grown in nutrient solution without or with Si (2 mM). As compared to plants non-supplied with Si, the Si concentration in leaf sheaths in cultivars BR-Irga-409 and Labelle supplied with Si increased by 77% and 84%, respectively. The relative lesion length of sheath blight was significantly lower in plants supplied with Si compared to non-supplied plants. There was no effect of Si or inoculation with R. solani on the concentrations of mannans, galactans, arabinans, xylans, glucans and sugars in the sheaths of plants from both cultivars. There was no variation in the concentrations of insoluble, soluble and total lignin between the cultivars. The concentrations of total and insoluble lignin were higher on plants supplied with Si regardless of inoculation with R. solani. In conclusion, the rice plants supplied with Si were more resistant to sheath blight due to an increase in the lignifications of the leaf sheath tissues and the lower concentration of total sugars.

Daniel Augusto, Schurt; Fabrício Ávila, Rodrigues; Jorge Luiz, Colodette; Vivian, Carré-Missio.

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Screening, identification and evaluation of potential biocontrol fungal endophytes against Rhizoctonia solani AG3 on potato plants.  

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Rhizoctonia solani is an important soilborne pathogen of potato plants whose control typically depends on chemicals. Here, we screened six fungal endophytes for the suppression of R. solani growth both in vitro and in a greenhouse. These isolates were identified using morphology and internal transcribed spacer regions of rDNA as Alternaria longipes, Epicoccum nigrum, Phomopsis sp., and Trichoderma atroviride. Both T. atroviride and E. nigrum showed significant in vitro inhibition of mycelial growth of R. solani, with the greatest inhibition zone observed for E. nigrum species in dual cultures. The highest inhibition was observed for T. atroviride. The inhibition rate was also significantly correlated with the culture filtrates of these isolates. Confocal microscopy showed that T. atroviride acts as a mycoparasite and competitor. However, E. nigrum and A. longipes produce secondary metabolites, while Phomospsis sp. competes for nutrients and space. Greenhouse experiments confirmed that T. atroviride and E. nigrum improved potato yield significantly and decreased the stem disease severity index of sensitive potato. PMID:20738401

Lahlali, Rachid; Hijri, Mohamed

2010-10-01

 
 
 
 
141

Biotic and abiotic factors associated with soil suppressiveness to Rhizoctonia solani / Fatores bióticos e abióticos associados à supressividade de solos a Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese As atividades agrícolas podem modificar as características do solo e, como conseqüência, alterar a incidência de patógenos veiculados pelo solo. Este trabalho avaliou a supressividade a R. solani em 59 amostras de solos de uma microbacia. As áreas amostradas foram selecionadas quanto à vegetação, in [...] cluindo mata, pasto/pousio, culturas anuais, culturas perenes e solo arado. As amostras de solo foram caracterizadas quanto às propriedades abióticas (pH, condutividade elétrica, teor de matéria orgânica, N total, P, K, Ca, Mg, Al, H, S, Na, Fe, Mn, Cu, Zn, B, capacidade de troca catiônica, soma de bases e saturação de bases) e bióticas (atividade microbiana do solo, avaliada pelo desprendimento de CO2 e hidrólise de diacetato de fluoresceína; comunidades de bactérias, fungos, actinomicetos, protozoários, Pseudomonas fluorescentes e Fusarium spp.). A contribuição e relação dessas variáveis para a supressividade a R. solani foram quantificadas por análise de coeficientes de trilha. Quando se avaliaram todas as amostras em conjunto, somente variáveis abióticas apresentaram correlação com a supressão a R. solani, mas o conjunto das variáveis explicou somente 51% da variação total. Entretanto, quando as amostras foram agrupadas e analisadas considerando o tipo de cobertura vegetal, o conjunto de variáveis explicou mais de 90% da variação da supressividade. Para as áreas de floresta e pasto/pousio, as quais foram classificadas como as mais supressivas, algumas variáveis abióticas e a hidrólise de diacetato de fluoresceína apresentaram correlação com a supressão de R. solani e o conjunto de variáveis explicou mais de 98% da supressividade nesses solos. Abstract in english Crop management may modify soil characteristics, and as a consequence, alter incidence of diseases caused by soilborne pathogens. This study evaluated the suppressiveness to R. solani in 59 soil samples from a microbasin. Soil sampling areas included undisturbed forest, pasture and fallow ground are [...] as, annual crops, perennial crops, and ploughed soil. The soil samples were characterized according to abiotic variables (pH; electrical conductivity; organic matter content; N total; P; K; Ca; Mg; Al; H; S; Na; Fe; Mn; Cu; Zn; B; cation exchange capacity; sum of bases and base saturation) and biotic variables (total microbial activity evaluated by the CO2 evolution and fluorescein diacetate hydrolysis; culturable bacterial, fungal, actinomycetes, protozoa, fluorescent Pseudomonas and Fusarium spp. communities). The contribution and relationships of these variables to suppression to R. solani were assessed by path analysis. When all samples were analyzed together, only abiotic variables correlated with suppression of R. solani, but the entire set of variables explained only 51% of the total variation. However, when samples were grouped and analyzed by vegetation cover, the set of evaluated variables in all cases accounted for more than 90% of the variation in suppression of the pathogen. In highly suppressive soils of forest and pasture/fallow ground areas, several abiotic variables and fluorescein diacetate hydrolysis correlated with suppression of R. solani and the set of variables explained more than 98% of suppressiveness.

Raquel, Ghini; Marcelo Augusto Boechat, Morandi.

2006-04-01

142

Analysis of Phaseolus vulgaris response to its association with Trichoderma harzianum (ALL-42) in the presence or absence of the phytopathogenic fungi Rhizoctonia solani and Fusarium solani.  

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The present study was carried out to evaluate the ability of Trichoderma harzianum (ALL 42-isolated from Brazilian Cerrado soil) to promote common bean growth and to modulate its metabolism and defense response in the presence or absence of the phytopathogenic fungi Rhizoctonia solani and Fusarium solani using a proteomic approach. T. harzianum was able to promote common bean plants growth as shown by the increase in root/foliar areas and by size in comparison to plants grown in its absence. The interaction was shown to modulate the expression of defense-related genes (Glu1, pod3 and lox1) in roots of P. vulgaris. Proteomic maps constructed using roots and leaves of plants challenged or unchallenged by T. harzianum and phytopathogenic fungi showed differences. Reference gels presented differences in spot distribution (absence/presence) and relative volumes of common spots (up or down-regulation). Differential spots were identified by peptide fingerprinting MALDI-TOF mass spectrometry. A total of 48 identified spots (19 for leaves and 29 for roots) were grouped into protein functional classes. For leaves, 33%, 22% and 11% of the identified proteins were categorized as pertaining to the groups: metabolism, defense response and oxidative stress response, respectively. For roots, 17.2%, 24.1% and 10.3% of the identified proteins were categorized as pertaining to the groups: metabolism, defense response and oxidative stress response, respectively. PMID:24878929

Pereira, Jackeline L; Queiroz, Rayner M L; Charneau, Sébastien O; Felix, Carlos R; Ricart, Carlos A O; da Silva, Francilene Lopes; Steindorff, Andrei Stecca; Ulhoa, Cirano J; Noronha, Eliane F

2014-01-01

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Evaluación de aislamientos de Trichoderma spp. contra Rhizoctonia solani y Sclerotium rolfsii bajo condiciones in vitro y de invernadero / Evaluation of Trichoderma spp. isolates against Rhizoctonia solani and Sclerotium rolfsii under in vitro and greenhouse conditions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Se evaluó la eficacia biológica de ocho aislamientos de Trichoderma spp. provenientes de suelos de Colombia para el control de los agentes causales de volcamiento, Sclerotium rolfsii y Rhizoctonia solani, bajo condiciones in vitro y de invernadero. Los análisis in vitro mostraron la capacidad antagó [...] nica de todos los aislamientos evaluados. En condiciones de invernadero, cuatro aislamientos fueron altamente eficaces contra S. rolfsii en plantas de fríjol en semillero (>90% de reducción de la enfermedad) y dos aislamientos fueron eficaces contra R. solani en plantas de algodón en semillero (58 y 61% de reducción de la enfermedad). El análisis UP-PCR y DS-PCR permitió determinar tres grupos de aislamientos; dentro de estas asociaciones formadas no se encontró ninguna relación evidente entre la posición en el dendrograma y la actividad antagónica, pero sí permitió separar las especies de Trichoderma por grupos, e incluso encontrar diferencias dentro de aislamientos de una misma especie. Los resultados muestran que el comportamiento micoparasítico de los aislamientos de Trichoderma spp. varía según el hongo fitopatógeno, evidenciando una amplia especificidad del antagonista por su sustrato, es decir por el hongo atacado; por lo tanto es necesario realizar cuidadosas selecciones del aislamiento de Trichoderma que se utilice en programas de control de fitopatógenos. Abstract in english The biological effectiveness of eight isolates of Trichoderma spp. coming from Colombian soils was evaluated under in vitro and greenhouse conditions for the controlled causal agents of damping-off, Sclerotium rolfsii and Rhizoctonia solani. In vitro analysis showed the antagonistic capacity of all [...] evaluated isolates. Under greenhouse conditions, four isolates were highly effective against S. rolfsii in bean nursery plants (>90% of disease reduction) and two isolates were effective against R. solani in cotton nursery plants (58 and 61% of disease reduction). The analysis UP-PCR and DS-PCR permitted the determination of three groups of isolates. Within these associations no clear link between the position in the dendrogram and antagonistic activity was found, but it allowed separation of species of Trichoderma by groups and even within isolates of the same species. The results indicate that the mycoparasitic capacity of Trichoderma spp. varies according to the phytopathogen fungi, showing a broad specificity of the antagonist for its substrate that is attacked by the fungus. Therefore it is necessary to make careful selections of the isolates of Trichoderma to be used in pathogens control programs.

Liliana, Hoyos-Carvajal; Paola, Chaparro; Miriam, Abramsky; Ilan, Chet; Sergio, Orduz.

2008-12-01

144

Efeito do tratamento de sementes de algodão com fungicidas no controle do tombamento de plântulas causado por Rhizoctonia solani / Effect of cotton seed dressing with fungicides for the control of seedling damping-off caused by Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho foi desenvolvido na Embrapa Agropecuária Oeste, em Dourados, MS, e teve por objetivo avaliar a eficiência de alguns fungicidas, aplicados no tratamento de sementes de algodão (Gossypium hirsutum), no controle do tombamento de plântulas causado por Rhizoctonia solani. Foi realizado test [...] e em casa de vegetação, utilizando a cultivar DeltaOpal. Sementes tratadas e não tratadas com fungicidas foram semeadas em areia contida em bandejas plásticas, dispostas em orifícios individuais, eqüidistantes e a 3 cm de profundidade. A inoculação com R. solani foi feita pela distribuição homogênea do inóculo do fungo na superfície do substrato. O fungo foi cultivado por 35 dias em sementes de aveia autoclavadas e trituradas em moinho (1 mm). Foram utilizados 9 g de inóculo por bandeja de areia. Foi observado efeito do tratamento fungicida na emergência inicial e final de plântulas, com destaque para triadimenol + pencycuron + tolylfluanid e triadimenol + tolylfluanid, seguidos de carboxin + thiram, triadimenol e carboxin + thiram + carbendazim. Os tratamentos mais eficientes no controle do tombamento de pós-emergência do algodoeiro foi obtido com a mistura triadimenol + pencycuron + tolylfluanid, seguida de triadimenol, triadimenol + tolylfluanid e carboxin+thiram. Nenhum dos fungicidas testados foi fitotóxico ao algodão. Abstract in english This work was carried out at Embrapa Agropecuaria Oeste, Dourados, MS in order to evaluate the efficiency of several fungicides, applied as seed dressing, in the control of damping-off caused by Rhizoctonia solani. Greenhouse testing was performed, using the cotton (Gossypium hirsutum) cv. DeltaOpal [...] . Treated and untreated seeds with the fungicides were sowed in sand contained in plastic flats, placed in individual and equidistant wells, 3 cm deep. Inoculation with R. solani was done by the homogeneous distribution of the fungus inoculum onto the substrate. The fungus was grown for 35 days on autoclaved oat seeds and then ground to powder using a mill (1 mm). Nine grams of the fungus inoculum were put into each plastic flat. The effect of the fungicide treatment on initial and final seedling emergence was observed, with distinction to triadimenol + pencycuron + tolylfluanid and triadimenol + tolylfluanid, followed by carboxin + thiram, triadimenol and carboxin + thiram + carbendazim. The most efficient treatments in the control of cotton seedling pos-emergence damping-off were triadimenol + pencycuron + tolylfluanid, followed by triadimenol, triadimenol + tolylfluanid and carboxin + thiram. No phytotoxic effects were observed on cotton.

AUGUSTO C. P., GOULART.

145

Evaluation of soil microorganisms with inhibitory activity against Rhizoctonia solani causal agent of the damping-off of canola.  

Science.gov (United States)

Pre- and post-emergence damping-off of canola seedlings caused by Rhizoctonia solani is a serious disease in Western Canada. Other fungi such as Fusarium spp. and Pythium spp. are also related to seedling damping-off. To-day, the search of soil bacteria is becoming a tool to use microorganisms as potential biocontrol agents for several plant diseases. The purpose of this research was to detect bacteria to biologically control R. solani, Pythium spp., and Fusarium spp. Soil samples were collected throughout Alberta during 1987 to isolate bacteria. Canola seedlings were also used to obtain bacteria from the same samples. Plant pathogenic fungi were tested to detect the antagonistic activity of the isolates. Tests were made with coated canola seeds, amendments and fresh of freeze-dried cells. Three hundred forty-one bacterial cultures were isolated. Only 16 inhibited fungal growth: 7 showed the same effects against R. solani and 9 showed uneven effects. Some isolates showed a weak action to Pythium spp. and Fusarium spp. Three isolates showed inhibitory effect on R. solani and Pythium spp. Isolate F1 improved by about 50% the germination of canola seeds in inoculated pots when compared with the inoculated control. Coated seeds had low germination and emergence was below the inoculated control. The emergence of canola seedlings was very much improved when isolate 147 was delivered as an amendment in inoculated pots. Identification showed that 3 bacterial belonged to Bacillus spp., 4 to green fluorescent Pseudomonas spp. and 2 were Streptomyces spp. PMID:2133515

Ciampi, L; Tewari, J P

1990-10-01

146

Is it necessary to soak rice grains to prepare Rhizoctonia solani AG-4 inoculum? / É necessário embeber os grãos de arroz para o preparo de inóculo de Rhizoctonia solani AG-4?  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Foi conduzido um estudo com o objetivo de avaliar os efeitos de quatro volumes de água (0, 30%, 60% e 90%, v/p) adicionados a grãos de arroz previamente embebidos em água por 24 horas antes de eles serem autoclavados e colonizados por Rhizoctonia solani sobre o desenvolvimento da podridão-radicular [...] de feijão, cv. 'Dufrix'. Grãos de arroz colonizados e não colonizados foram misturados em vasos contendo substrato de solo e areia (2:1), com posterior semeadura de feijão. Baseados nos resultados de área abaixo da curva de emergência das plantas, altura das plantas, massa de plantas secas e severidade da doença, conclui-se que o inóculo é mais eficiente em causar doença quando não se adiciona água aos grãos de arroz antes de eles serem autoclavados. Abstract in english A study was conducted to evaluate the effects on the development of root rot on common bean, cv. 'Dufrix' after treatment with four volumes of water (0, 30%, 60%, and 90%, v/w) added to rice grains previously immersed in water for 24 hours before autoclaving and colonization of grains by Rhizoctonia [...] solani AG-4. Colonized rice grains and non-infested rice grains were mixed in pots with sterilized soil and sand (2:1), where beans were sown. Based on results of area under plant emergence curve, plant height, plant dry weight, and disease severity, we conclude that inoculum is more effective in causing disease when no water is added to the rice grains before autoclaving.

Trazilbo J., Paula Júnior; Rogério F., Vieira; Waldir C., Jesus Junior; Bernhard, Hau; Hudson, Teixeira.

147

Evaluación de métodos de inoculación de Rhizoctonia solani sobre germoplasma de arroz en campo Assessment of Rhizoctonia solani inoculation techniques on rice germplasm on the field  

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Full Text Available El éxito de la selección de individuos resistentes a las enfermedades, se basa en la utilización de métodos de inoculación que induzcan un nivel de incidencia de la enfermedad cercana al 100%. Con el objeto de determinar un método eficiente de inoculación de arroz con R. solani, se llevó a cabo un ensayo durante los años 2001 y 2002 en Araure, estado Portuguesa. El ensayo se realizó en bloques al azar con cuatro repeticiones, utilizando dos fuentes de inóculo, esclerocios (Es y granos de arroz infectados con R. solani (GAI. Los métodos de inoculación con GAI difirieron en la dosis, forma y época de aplicación del inóculo. Los resultados indican que la inoculación con Es fue más confiable, con una incidencia superior al 98%, en ambos años. Los resultados obtenidos con GAI fueron variables, al ser afectados por las precipitaciones ocurridas en el período post-inoculación, en el año 2002. Durante el año 2001, sin embargo, se alcanzó una incidencia cercana al 100%, en las parcelas donde se aplicaron 25 g de arroz infectado, al voleo, 70 días después de la siembra. Este método es más práctico y puede ser recomendado, en el caso donde la cantidad de individuos a ser evaluados es elevada, si la inoculación coincide con el período de salidas deAbstract Resistance breeding success depends on the use of efficient inoculation techniques, which guarantee levels of disease incidence close to 100 %. In order to select an efficient rice inoculation technique with R. solani, an experiment was carried out during 2001 and 2002 in Araure, Portuguesa. The experimental design was a Randomized Complete Block with four repetitions, where sclerotia (Sc and rice grains infected by R. solani (IRG were used as sources of inocula. Techniques based on IRG differed in the amount, form and time of inocula application. Results indicate that Sc inoculation was the most reliable technique, since incidence levels were close to 100%, in both years. Results attained with IRG were variable, being affected by rains that occurred on the post-inoculation period, in 2002. During the 2001 experiment, however, an incidence level close to 100% was reached when 25 g of IRG were broadcasted on the plots, 70 days after sowing. This technique is easier and may be recommended in cases where the amount of individuals to be evaluated is high. The IRG technique should not be used during the peak of the rainy season to reduce the odds of having rains on the post-inoculation period

N. J. Delgado¹

2004-06-01

148

EFECTO DE DIFERENTES DERIVADOS DE LA QUITINA SOBRE EL CRECIMIENTO In Vitro DEL HONGO Rhizoctonia solani Kuhn  

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Full Text Available En la Estación Experimental del Arroz "Los Palacios", se estudió el efecto in vitro de diferentes derivados de la quitina (QC, HMK-70, Q-63, HQ-63, D-glucosamina y N-acetil-glucosamina sobre el crecimiento del hongo Rhizoctonia solani Kuhn. Para ello se evaluó el diámetro de la colonia a los dos, cuatro y seis días, determinándose el porcentaje de inhibición del crecimiento del hongo. Los resultados mostraron un marcado efecto inhibitorio de la cepa evaluada en presencia de las quitosanas HMK-70, Q-63 y su correspondiente hidrolizado enzimático HQ-63; dicho efecto aumentó con la concentración de los productos, destacándose los dos últimos, con una inhibición del 100 % a la concentración de 1 mg.mL-1. Por su parte, la D-glucosamina y la N-Acetil-Glucosamina no mostraron inhibición del crecimiento micelial, mientras que la quitina coloidal (QC presentó un ligero efecto inhibitorio sobre el hongo en estudio.

Yanet Parra

2002-01-01

149

Diversity of Fluorescent Pseudomonas in Potato Crops of the Cundiboyacense Region and its in vitro Antagonic Activity against Rhizoctonia solani  

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Full Text Available Fluorescent Pseudomonas are one of the most important benefic bacteria of the rizhosphere. It is because they can control some soil borne phytopatogen agents as a result of their antagonistic capacity. There are few works about the composition and diversity of fluorescent Pseudomonas in tropical countries. In this work we studied the composition of fluorescent Pseudomonas form different potato crops located at the Cundiboyacense región between 2100 and 3200 mosl, which is the most important area of potato production in Colombia. This study also assesses the effect of some crop practices variables on rizosphere bacteria richness and diversity. Finally, it was determined the antagonistic capacity of some Pseudomonas fluorescens isolates against Rhizoctonia solani. A total of 45 rhizosphere samples were taken from 15 potato fields. To isolate the Pseudomonas it was used king B medium modified by us. Our results showed that this modified medium consistently allowed a more efficient recovery of the fluorescent Pseudomonas than the media reported in the literature. 80.7% and 82.7% of the fluorescent Pseudomonas isolated from the rizosphere and rizoplane respectively were Pseudomonas fluorescens. It suggest a low fluorescent pseudomonas diversity. Our work also denotes an effect of the maize-potato crop rotation strategy on the amount of the fluorescent Pseudomonas isolated from the rizosphere. These results may have importance in designing appropriate strategies for bio-controlling soil borne phytopathogens. In tropical countries like Colombia, this knowledge might help to improve crop yields. Finally it was found native isolates with antagonistic activity against Rhizoctonia solani in the bioassays in vitro, such results if not assure an efficient control of the pathogen in field conditions, may give an idea of the potentiality of P.fluorescens to be applied as bacterial community, strains or derived products of them.

D. Uribe

2011-12-01

150

Molecular identification of thirteen isolates of Trichoderma spp. and evaluation of their pathogenicity towards Rhizoctonia solani Kühn / Identificación molecular y evaluación patogénica de trece aislamientos de Trichoderma spp. frente a Rhizoctonia solani Kühn  

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Full Text Available SciELO Cuba | Language: English Abstract in spanish La incidencia de las enfermedades causadas por Rhizoctonia solani Kühn en las plantas aumenta cada año. Su control es fundamentalmente con productos químicos, en su mayoría muy tóxicos. Por tal razón, se investigan alternativas bioplaguicidas. Trichoderma spp. es uno de los hongos más utilizados par [...] a el control biológico de plagas, por sus propiedades y mecanismos de acción: competencia por el sustrato, antibiosis y micoparasitismo. Este trabajo tuvo como objetivos la identifi cación molecular y evaluación patogénica de 13 aislamientos del género Trichoderma frente a aislamientos de R. solani. Se evaluó su efecto antibiótico sobre aislamientos de 3 grupos de anastomosis de R. solani (AG-2.1, AG-5, AG-8) por el método de celofán. La identificación molecular partió de la secuenciación del espaciador interno del transcrito de la región del ADN ribosomal y del factor de elongación de la traducción EF1A. Más del 70 % de los aislamientos evaluados ejerció un efecto fungistático; mientras que el resto actuó como fungicida. La evaluación de la eficacia técnica en condiciones de campo corroboró estos resultados. A partir de la secuenciación y comparación de los datos de las secuencias depositadas en TrichoBLAST/GenBank, se comprobó que todos los aislamientos tenían el 100 % de identidad con la especie Trichoderma asperellum Samuels. Se seleccionaron los aislamientos 3, 13, 17, 75, 78, 85 y 90 como promisorios agentes de control biológico, por su alto potencial antibiótico y eficacia técnica en condiciones de campo. Abstract in english Disease caused by Rhizoctonia solani Kühn infestations has become a growing problem for commercially important crops. Although this fungus is usually controlled through the application of chemicals, the heavy ecological and financial toll of the latter has prompted for research on biopesticides as a [...] viable alternative. Trichoderma spp. is a well-known fungus often used for the biological control of crop pests, whose anti-fungal mechanisms include competition for the substrate, antibiosis and/or mycoparasitism. In the present work, we have used molecular techniques (sequencing of amplicons from the internal transcribed spacer of ribosomal DNA and the EF1A translation elongation factor) for the taxonomic identification of 13 Trichoderma spp. isolates in our collection, also evaluating their antibiotic effect on strains from three anastomosis groups of R. solani (AG-2.1, AG-5, AG-8) by the cellophane method. The sequences obtained from all isolates exhibited 100 % identity with deposited T. asperellum Samuels sequences in TrichoBLAST/GenBank, enabling their taxonomic assignment to this species. When analyzed by in vitro tests, over 70 % of the isolates exhibited a fungistatic effect towards R. solani, with the remaining strains exhibiting fungicidal activity; these results were later corroborated by technical efficacy tests under field conditions. Isolates 3, 13, 17, 75, 78, 85 and 90 were selected as potential biocontrol agents due to their high antibiotic activity and technical efficacy under field conditions.

Danay, Infante; Benedicto, Martínez; Belkis, Peteira; Yusimy, Reyes; Alfredo, Herrera.

2013-03-01

151

Efecto diferencial de seis aislamientos de trichoderma sobre la severidad de Rhizoctonia solani, desarrollo radical y crecimiento de plantas de maíz / Differential effect of six Trichoderma isolates on root development, plant growth and severity of Rhizoctonia solani on mayze  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish La mancha bandeada de la hoja en maíz, Rhizoctonia solani Kuhn, ha incrementado su incidencia en Venezuela y ocasiona considerables pérdidas en la producción. En muchos casos la microbiota del suelo sirve para proteger a la planta del ataque de patógenos y contribuye a su mayor desarrollo. Para estu [...] diar medidas de biocontrol de R. solani se seleccionaron seis aislamientos de Trichoderma provenientes de la rizósfera de plantas de maíz colectadas en varias localidades de los estados Portuguesa y Yaracuy, las cuales fueron utilizadas en pruebas de antagonismo en vivero con un sustrato esterilizado. En el sustrato se hicieron dos hoyos y en ellos se colocaron dos granos de arroz esterilizados y 2 mL de solución de esporas del antagonista a 3-7x10(6) conidios·mL-1. Luego se colocó una semilla de maíz híbrido D2000 en cada hoyo y dos esclerocios de R. solani, se adicionaron 3 mL de la solución del antagonista y se cubrió con suelo esterilizado. Con relación a la sobrevivencia de plantas, hubo un efecto positivo en los tratamientos donde se utilizaron las cepas de Trichoderma, obteniéndose valores entre 70 y 90 %. En cuanto a la severidad de la enfermedad en la planta hasta los 60 días, se obtuvieron valores de 82,5 % en el testigo y 16,2 % en el mejor tratamiento con Trichoderma. Para un aislamiento proveniente de Píritu-estado Portuguesa se produjo el avance de la enfermedad fue el menor. Este aislamiento, seguido por el procedente de Yaritagua-estado Yaracuy, propiciaron un mayor crecimiento de la planta y mayor desarrollo radical. Abstract in english The banded leaf spot disease on maize, Rhizoctonia solani Kuhn, has increased its incidence in Venezuela, causing considerable damages and yield reduction. In many cases, soil microbiota can protect the plant from the pathogen attack and contributes to better plant development. In order to study for [...] ms of biocontrol of R. solani, six isolations of Trichoderma obtained from maize plant rizosphere were collected in several localities of Portuguesa and Yaracuy States; the isolations were used in antagonism tests on a sterilized substrate in nursery. Two orifices were made in the substrate and sterilized grains of rice were placed on them, covering with 2 mL of spore solution of the antagonist (3-7x10(6) conidia mL-1). Later, one maize of seed hybrid D2000 and two esclerotia of R. solani was placed in each hole and added 3 mL of the solution of the antagonist, covering with sterilized soil. In relation to plant survival, there was a positive effect of the treatments where Trichoderma was used, obtaining values between 70 and 90 %. As far as plant disease severity up to 60 days, it was obtained a value of 82.5 % in the control and 16.2 % in the best treatment with Trichoderma. For the isolation coming from Píritu-Portuguesa State, the advance of the disease was the smallest. This isolation, followed by the one coming from Yaritagua-Yaracuy State, promoted a greater plant growth and better root development.

Yuleidy, López; Juan B, Pineda; Alexander, Hernández; Dilcia, Ulacio.

152

Molecular identification of thirteen isolates of Trichoderma spp. and evaluation of their pathogenicity towards Rhizoctonia solani Kühn / Identificación molecular y evaluación patogénica de trece aislamientos de Trichoderma spp. frente a Rhizoctonia solani Kühn  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: English Abstract in spanish La incidencia de las enfermedades causadas por Rhizoctonia solani Kühn en las plantas aumenta cada año. Su control es fundamentalmente con productos químicos, en su mayoría muy tóxicos. Por tal razón, se investigan alternativas bioplaguicidas. Trichoderma spp. es uno de los hongos más utilizados par [...] a el control biológico de plagas, por sus propiedades y mecanismos de acción: competencia por el sustrato, antibiosis y micoparasitismo. Este trabajo tuvo como objetivos la identifi cación molecular y evaluación patogénica de 13 aislamientos del género Trichoderma frente a aislamientos de R. solani. Se evaluó su efecto antibiótico sobre aislamientos de 3 grupos de anastomosis de R. solani (AG-2.1, AG-5, AG-8) por el método de celofán. La identificación molecular partió de la secuenciación del espaciador interno del transcrito de la región del ADN ribosomal y del factor de elongación de la traducción EF1A. Más del 70 % de los aislamientos evaluados ejerció un efecto fungistático; mientras que el resto actuó como fungicida. La evaluación de la eficacia técnica en condiciones de campo corroboró estos resultados. A partir de la secuenciación y comparación de los datos de las secuencias depositadas en TrichoBLAST/GenBank, se comprobó que todos los aislamientos tenían el 100 % de identidad con la especie Trichoderma asperellum Samuels. Se seleccionaron los aislamientos 3, 13, 17, 75, 78, 85 y 90 como promisorios agentes de control biológico, por su alto potencial antibiótico y eficacia técnica en condiciones de campo. Abstract in english Disease caused by Rhizoctonia solani Kühn infestations has become a growing problem for commercially important crops. Although this fungus is usually controlled through the application of chemicals, the heavy ecological and financial toll of the latter has prompted for research on biopesticides as a [...] viable alternative. Trichoderma spp. is a well-known fungus often used for the biological control of crop pests, whose anti-fungal mechanisms include competition for the substrate, antibiosis and/or mycoparasitism. In the present work, we have used molecular techniques (sequencing of amplicons from the internal transcribed spacer of ribosomal DNA and the EF1A translation elongation factor) for the taxonomic identification of 13 Trichoderma spp. isolates in our collection, also evaluating their antibiotic effect on strains from three anastomosis groups of R. solani (AG-2.1, AG-5, AG-8) by the cellophane method. The sequences obtained from all isolates exhibited 100 % identity with deposited T. asperellum Samuels sequences in TrichoBLAST/GenBank, enabling their taxonomic assignment to this species. When analyzed by in vitro tests, over 70 % of the isolates exhibited a fungistatic effect towards R. solani, with the remaining strains exhibiting fungicidal activity; these results were later corroborated by technical efficacy tests under field conditions. Isolates 3, 13, 17, 75, 78, 85 and 90 were selected as potential biocontrol agents due to their high antibiotic activity and technical efficacy under field conditions.

Danay, Infante; Benedicto, Martínez; Belkis, Peteira; Yusimy, Reyes; Alfredo, Herrera.

153

Efecto diferencial de seis aislamientos de trichoderma sobre la severidad de Rhizoctonia solani, desarrollo radical y crecimiento de plantas de maíz Differential effect of six Trichoderma isolates on root development, plant growth and severity of Rhizoctonia solani on mayze  

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Full Text Available La mancha bandeada de la hoja en maíz, Rhizoctonia solani Kuhn, ha incrementado su incidencia en Venezuela y ocasiona considerables pérdidas en la producción. En muchos casos la microbiota del suelo sirve para proteger a la planta del ataque de patógenos y contribuye a su mayor desarrollo. Para estudiar medidas de biocontrol de R. solani se seleccionaron seis aislamientos de Trichoderma provenientes de la rizósfera de plantas de maíz colectadas en varias localidades de los estados Portuguesa y Yaracuy, las cuales fueron utilizadas en pruebas de antagonismo en vivero con un sustrato esterilizado. En el sustrato se hicieron dos hoyos y en ellos se colocaron dos granos de arroz esterilizados y 2 mL de solución de esporas del antagonista a 3-7x10(6 conidios·mL-1. Luego se colocó una semilla de maíz híbrido D2000 en cada hoyo y dos esclerocios de R. solani, se adicionaron 3 mL de la solución del antagonista y se cubrió con suelo esterilizado. Con relación a la sobrevivencia de plantas, hubo un efecto positivo en los tratamientos donde se utilizaron las cepas de Trichoderma, obteniéndose valores entre 70 y 90 %. En cuanto a la severidad de la enfermedad en la planta hasta los 60 días, se obtuvieron valores de 82,5 % en el testigo y 16,2 % en el mejor tratamiento con Trichoderma. Para un aislamiento proveniente de Píritu-estado Portuguesa se produjo el avance de la enfermedad fue el menor. Este aislamiento, seguido por el procedente de Yaritagua-estado Yaracuy, propiciaron un mayor crecimiento de la planta y mayor desarrollo radical.The banded leaf spot disease on maize, Rhizoctonia solani Kuhn, has increased its incidence in Venezuela, causing considerable damages and yield reduction. In many cases, soil microbiota can protect the plant from the pathogen attack and contributes to better plant development. In order to study forms of biocontrol of R. solani, six isolations of Trichoderma obtained from maize plant rizosphere were collected in several localities of Portuguesa and Yaracuy States; the isolations were used in antagonism tests on a sterilized substrate in nursery. Two orifices were made in the substrate and sterilized grains of rice were placed on them, covering with 2 mL of spore solution of the antagonist (3-7x10(6 conidia mL-1. Later, one maize of seed hybrid D2000 and two esclerotia of R. solani was placed in each hole and added 3 mL of the solution of the antagonist, covering with sterilized soil. In relation to plant survival, there was a positive effect of the treatments where Trichoderma was used, obtaining values between 70 and 90 %. As far as plant disease severity up to 60 days, it was obtained a value of 82.5 % in the control and 16.2 % in the best treatment with Trichoderma. For the isolation coming from Píritu-Portuguesa State, the advance of the disease was the smallest. This isolation, followed by the one coming from Yaritagua-Yaracuy State, promoted a greater plant growth and better root development.

Yuleidy López

2010-04-01

154

Efecto diferencial de seis aislamientos de trichoderma sobre la severidad de Rhizoctonia solani, desarrollo radical y crecimiento de plantas de maíz / Differential effect of six Trichoderma isolates on root development, plant growth and severity of Rhizoctonia solani on mayze  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish La mancha bandeada de la hoja en maíz, Rhizoctonia solani Kuhn, ha incrementado su incidencia en Venezuela y ocasiona considerables pérdidas en la producción. En muchos casos la microbiota del suelo sirve para proteger a la planta del ataque de patógenos y contribuye a su mayor desarrollo. Para estu [...] diar medidas de biocontrol de R. solani se seleccionaron seis aislamientos de Trichoderma provenientes de la rizósfera de plantas de maíz colectadas en varias localidades de los estados Portuguesa y Yaracuy, las cuales fueron utilizadas en pruebas de antagonismo en vivero con un sustrato esterilizado. En el sustrato se hicieron dos hoyos y en ellos se colocaron dos granos de arroz esterilizados y 2 mL de solución de esporas del antagonista a 3-7x10(6) conidios·mL-1. Luego se colocó una semilla de maíz híbrido D2000 en cada hoyo y dos esclerocios de R. solani, se adicionaron 3 mL de la solución del antagonista y se cubrió con suelo esterilizado. Con relación a la sobrevivencia de plantas, hubo un efecto positivo en los tratamientos donde se utilizaron las cepas de Trichoderma, obteniéndose valores entre 70 y 90 %. En cuanto a la severidad de la enfermedad en la planta hasta los 60 días, se obtuvieron valores de 82,5 % en el testigo y 16,2 % en el mejor tratamiento con Trichoderma. Para un aislamiento proveniente de Píritu-estado Portuguesa se produjo el avance de la enfermedad fue el menor. Este aislamiento, seguido por el procedente de Yaritagua-estado Yaracuy, propiciaron un mayor crecimiento de la planta y mayor desarrollo radical. Abstract in english The banded leaf spot disease on maize, Rhizoctonia solani Kuhn, has increased its incidence in Venezuela, causing considerable damages and yield reduction. In many cases, soil microbiota can protect the plant from the pathogen attack and contributes to better plant development. In order to study for [...] ms of biocontrol of R. solani, six isolations of Trichoderma obtained from maize plant rizosphere were collected in several localities of Portuguesa and Yaracuy States; the isolations were used in antagonism tests on a sterilized substrate in nursery. Two orifices were made in the substrate and sterilized grains of rice were placed on them, covering with 2 mL of spore solution of the antagonist (3-7x10(6) conidia mL-1). Later, one maize of seed hybrid D2000 and two esclerotia of R. solani was placed in each hole and added 3 mL of the solution of the antagonist, covering with sterilized soil. In relation to plant survival, there was a positive effect of the treatments where Trichoderma was used, obtaining values between 70 and 90 %. As far as plant disease severity up to 60 days, it was obtained a value of 82.5 % in the control and 16.2 % in the best treatment with Trichoderma. For the isolation coming from Píritu-Portuguesa State, the advance of the disease was the smallest. This isolation, followed by the one coming from Yaritagua-Yaracuy State, promoted a greater plant growth and better root development.

Yuleidy, López; Juan B, Pineda; Alexander, Hernández; Dilcia, Ulacio.

2010-04-01

155

Controle de Rhizoctonia solani e Fusarium oxysporum f.sp. phaseoli por biopreparados de isolados de Trichoderma spp. / Rhizoctonia solani and Fusarium oxysporum f.sp. phaseoli control by biopreparation with Trichoderma spp. isolates  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os experimentos objetivaram avaliar em condições de casa de vegetação o biocontrole dos fitopatógenos Rhizoctonia solani (RS) e Fusarium oxysporum f.sp. phaseoli (FOP) em alface (Lactuca sativa L.) cultivar Regina, e feijão-vagem (Phaseolus vulgaris L.) cultivar Alessa, respectivamente, utilizando c [...] omo agentes antagonistas, 10 isolados de Trichoderma spp. selecionados em testes in vitro. Foram feitos biopreparados à base de arroz previamente colonizado por isolados de Trichoderma spp. e posteriormente triturados. Para a realização dos testes, os biopreparados foram inoculados previamente na proporção de 10(9) conídios.mL-1, em substrato comercial para produção de mudas. Após sete dias, os patógenos foram introduzidos separadamente em duas concentrações distintas: R. solani na proporção de 144 mg de meio de arroz por kg de substrato e F. oxysporum f.sp. phaseoli inoculado na forma de suspensão contendo 4,75 x 10(6) conídios.mL-1. Avaliou-se a influência dos biopreparados na % de damping-off de pós-emergência em plantas de alface e a severidade de murcha em plantas de feijão-vagem. O biopreparado referente ao isolado T-03 foi o mais eficiente no controle de R. solani em plantas de alface cultivar Regina, por ter reduzido a incidência de damping-off de pós-emergência nessa cultura. Por outro lado, nenhum dos biopreparados apresentou efeito antagonista satisfatório à F. oxysporum f.sp. phaseoli em plantas de feijão-vagem. Abstract in english The experiments aimed to evaluate under greenhouse conditions the biocontrol of plant pathogens Rhizoctonia solani (RS) and Fusarium oxysporum f.sp. phaseoli (FOP) in lettuce (Lactuca sativa L.) cultivar Regina and in common bean (Phaseolus vulgaris L.) cultivar Alessa, respectively, using as antago [...] nistic agents 10 Trichoderma spp. isolates selected from in vitro tests. Inoculants were prepared with rice previously colonized by Trichoderma spp. and subsequently ground. For the tests, the antagonists were previously inoculated at a ratio of 10(9) conidia mL-1 on commercial substrate for seedling production. Following seven days, the pathogens were separately introduced at two different concentrations: R. solani at a ratio of 144 mg rice medium per kg of substrate and F oxysporum f.sp. phaseoli inoculated as a suspension containing 4.75 x 10(6) conidia mL-1. The influence of antagonists on % post-emergence damping-off in lettuce and the severity of wilt in common beans were evaluated. The biopreparation with T-03 isolate was most effective in controlling R. solani in lettuce cultivar Regina, for having reduced the incidence of post-emergence damping-off in this culture. On the other hand, none of the biopreparations showed satisfactory antagonistic effect on F. oxysporum f.sp. phaseoli in common bean plants.

Pedro Paulo, Dias; Ricardo Luis Louro, Berbara; Maria do Carmo de Araújo, Fernandes.

2013-12-01

156

The impact of the pathogen Rhizoctonia solani and its beneficial counterpart Bacillus amyloliquefaciens on the indigenous lettuce microbiome  

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Full Text Available Lettuce belongs to the most commonly raw eaten food worldwide and its microbiome plays an important role for both human and plant health. Yet, little is known about the impact of potentially occurring pathogens and beneficial inoculants of the indigenous microorganisms associated with lettuce. To address this question we studied the impact of the phytopathogenic fungus Rhizoctonia solani and the biological control agent Bacillus amyloliquefaciens FZB42 on the indigenous rhizosphere and phyllosphere community of greenhouse-grown lettuce at two plant stages. The rhizosphere and phyllosphere gammaproteobacterial microbiomes of lettuce plants showed clear differences in their overall and core microbiome composition as well as in corresponding diversity indices. The rhizosphere was dominated by Xanthomonadaceae (48% and Pseudomonadaceae (37% with Rhodanobacter, Pseudoxanthomonas, Dokdonella, Luteimonas, Steroidobacter, Thermomonas as core inhabitants, while the dominating taxa associated to phyllosphere were Pseudomonadaceae (54%, Moraxellaceae (16% and Enterobacteriaceae (25% with Alkanindiges, Pantoea and a group of Enterobacteriaceae unclassified at genus level. The preferential occurrence of enterics in the phyllosphere was the most significant difference between both habitats. Additional enhancement of enterics on the phyllosphere was observed in bottom rot diseased lettuce plants, while Acinetobacter and Alkanindiges were identified as indicators of healthy plants. Interestingly, the microbial diversity was enhanced by treatment with both the pathogen, and the co-inoculated biological control agent. The highest impact and bacterial diversity was found by Rhizoctonia inoculation, but FZB42 lowered the impact of Rhizoctonia on the microbiome. This study shows that the indigenous microbiome shifts as a consequence to pathogen attack but FZB42 can compensate these effects, which supports their role as biocontrol agent and suggests a novel mode of action.

GabrieleBerg

2014-04-01

157

The impact of the pathogen Rhizoctonia solani and its beneficial counterpart Bacillus amyloliquefaciens on the indigenous lettuce microbiome.  

Science.gov (United States)

Lettuce belongs to the most commonly raw eaten food worldwide and its microbiome plays an important role for both human and plant health. Yet, little is known about the impact of potentially occurring pathogens and beneficial inoculants of the indigenous microorganisms associated with lettuce. To address this question we studied the impact of the phytopathogenic fungus Rhizoctonia solani and the biological control agent Bacillus amyloliquefaciens FZB42 on the indigenous rhizosphere and phyllosphere community of greenhouse-grown lettuce at two plant stages. The rhizosphere and phyllosphere gammaproteobacterial microbiomes of lettuce plants showed clear differences in their overall and core microbiome composition as well as in corresponding diversity indices. The rhizosphere was dominated by Xanthomonadaceae (48%) and Pseudomonadaceae (37%) with Rhodanobacter, Pseudoxanthomonas, Dokdonella, Luteimonas, Steroidobacter, Thermomonas as core inhabitants, while the dominating taxa associated to phyllosphere were Pseudomonadaceae (54%), Moraxellaceae (16%) and Enterobacteriaceae (25%) with Alkanindiges, Pantoea and a group of Enterobacteriaceae unclassified at genus level. The preferential occurrence of enterics in the phyllosphere was the most significant difference between both habitats. Additional enhancement of enterics on the phyllosphere was observed in bottom rot diseased lettuce plants, while Acinetobacter and Alkanindiges were identified as indicators of healthy plants. Interestingly, the microbial diversity was enhanced by treatment with both the pathogen, and the co-inoculated biological control agent. The highest impact and bacterial diversity was found by Rhizoctonia inoculation, but FZB42 lowered the impact of Rhizoctonia on the microbiome. This study shows that the indigenous microbiome shifts as a consequence to pathogen attack but FZB42 can compensate these effects, which supports their role as biocontrol agent and suggests a novel mode of action. PMID:24795707

Erlacher, Armin; Cardinale, Massimiliano; Grosch, Rita; Grube, Martin; Berg, Gabriele

2014-01-01

158

Relato de Rhizoctonia solani AG-4 HG I em crisântemo (Papiro Branco e Amarelo) e R. solani AG-4 HG III em gipsófila no estado de São Paulo, Brasil, e sua patogenicidade cruzada / Report of Rhizoctonia solani AG-4 HG I on chrysanthemum (White and Yellow Papyrus) and R. solani AG-4 HG III on gypsophila in the São Paulo State, Brazil, and their cross pathogenicity  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Atualmente, grupamento de anastomose (AG) de Rhizoctonia sp. em crisântemo e ocorrência deste fungo em gipsófila ainda não foram relatados no Brasil. Assim, realizou-se teste de patogenicidade normal e cruzada e sequenciamento da região ITS-5.8S rDNA para identificar o AG de isolado obtido de planta [...] s de crisântemo (Papiro Branco) e de gipsófila, ambas originárias de Holambra / São Paulo, Brasil. Após os testes, relata-se pela primeira vez a ocorrência de R. solani AG-4 HG I em crisântemo (Papiro Branco e Amarelo) e R. solani AG-4 HG III em gipsófila, no estado de São Paulo, Brasil, e, também, a sua patogenicidade cruzada. Abstract in english Currently, anastomosis groups (AG) of Rhizoctonia sp. on chrysanthemum and occurrence of this fungus on gypsophila have not been reported in Brazil. However, in the present study, normal and cross pathogenicity and sequencing of ITS-5.8S rDNA regions were used to confirm the AG of isolate of Rhizoct [...] onia sp. obtained from chrysanthemum (White Papyrus) and from gypsophila plants cultivated in Holambra / São Paulo, Brazil. After these tests, it was confirmed the report of Rhizoctonia solani AG-4 HG I on chrysanthemum (White and Yellow Papyrus) and R. solani AG-4 HG III on gypsophila in the São Paulo state, Brazil, and also their cross pathogenicity.

César Júnior, Bueno; Wagner, Bettiol; Edisson Chavarro, Mesa; Paulo Cézar, Ceresini.

2013-12-01

159

Relato de Rhizoctonia solani AG-4 HG I em crisântemo (Papiro Branco e Amarelo) e R. solani AG-4 HG III em gipsófila no estado de São Paulo, Brasil, e sua patogenicidade cruzada / Report of Rhizoctonia solani AG-4 HG I on chrysanthemum (White and Yellow Papyrus) and R. solani AG-4 HG III on gypsophila in the São Paulo State, Brazil, and their cross pathogenicity  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Atualmente, grupamento de anastomose (AG) de Rhizoctonia sp. em crisântemo e ocorrência deste fungo em gipsófila ainda não foram relatados no Brasil. Assim, realizou-se teste de patogenicidade normal e cruzada e sequenciamento da região ITS-5.8S rDNA para identificar o AG de isolado obtido de planta [...] s de crisântemo (Papiro Branco) e de gipsófila, ambas originárias de Holambra / São Paulo, Brasil. Após os testes, relata-se pela primeira vez a ocorrência de R. solani AG-4 HG I em crisântemo (Papiro Branco e Amarelo) e R. solani AG-4 HG III em gipsófila, no estado de São Paulo, Brasil, e, também, a sua patogenicidade cruzada. Abstract in english Currently, anastomosis groups (AG) of Rhizoctonia sp. on chrysanthemum and occurrence of this fungus on gypsophila have not been reported in Brazil. However, in the present study, normal and cross pathogenicity and sequencing of ITS-5.8S rDNA regions were used to confirm the AG of isolate of Rhizoct [...] onia sp. obtained from chrysanthemum (White Papyrus) and from gypsophila plants cultivated in Holambra / São Paulo, Brazil. After these tests, it was confirmed the report of Rhizoctonia solani AG-4 HG I on chrysanthemum (White and Yellow Papyrus) and R. solani AG-4 HG III on gypsophila in the São Paulo state, Brazil, and also their cross pathogenicity.

César Júnior, Bueno; Wagner, Bettiol; Edisson Chavarro, Mesa; Paulo Cézar, Ceresini.

160

Ribosome Inactivating Protein of barley enhanced resistance to Rhizoctonia solani in transgenic potato cultivar 'Desirée' in greenhouse conditions  

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Full Text Available In the present study, the potato cultivar 'Desirée' was transformed via Agrobacterium tumefaciens strain LBA4404 containing the plasmid pBIN19 which harbors the Ribosome Inactivating Protein (rip30. The potato leaf discs were used as an explant for transformation. The in vitro regeneration parameters (percentage of callus regenerated, number of shoots per callus, percentage of regenerated roots and percentage of the transgenic plants were evaluated. The PCR technique was used for identification of transformed plants. Southern and Western blot analyses were applied for molecular characterization of the transgenic clones. A greenhouse assay was carried out to evaluate the resistance to Rhizoctonia solani pathogen of transgenic clones expressing the rip30 gene. The results revealed that not all the plants developed in selective medium were positive for the corresponding gene using the PCR technique. Southern blot analysis demonstrated that the tested transgenic plants integrated three copies of rip30 gene into their genome. The expression of the RIP30 protein was confirmed in the leaf extracts of the transgenic clones by Western blot analysis. Resistance evaluation of the transgenic plants in greenhouse conditions showed that disease incidence and severity were reduced for R. solani.

M'hamdi, M.

2013-01-01

 
 
 
 
161

Biological Control Potential of Two Streptomyces Isolates on Rhizoctonia solani, the Causal Agent of Damping-off of Sugar Beet  

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Full Text Available Biological control of sugar beet damping-off of Rhizoctonia solani by two Streptomyces isolates (S2 and C was evaluated in this study. The in vitro antagonism assays showed that active isolates had inhibitory effects on mycelium growth of the three R. solani AG-4 isolates (Rs1, Rs2 and Rs3. Soil treatment either with isolate S2 or C formulation inhibited the disease completely and increased seedling stand in infected and uninfected treatments significantly (p<0.05. Compared to controls, all treatments containing bacteria had enhanced shoot and root dry weight and root density. Both bacterial isolates maintained normal growth in pH ranges of 5.6, 7.2 and 8.0 at 29°C. Isolate C grew in pH ranges 5.6, 7.2 and 8.0 at 23-37°C, isolate S2 grew at 18-37°C in pH 5.6-8.0 but did not grow in acidic medium at 37°C. When pH decreased to 5.0, growth of C decreased and S2 inhibited. To elucidate the mode of antagonism, chitinase activity and siderophore production were evaluated. Both isolates showed chitinase activity on medium containing colloidal chitin. Biosynthesis of siderophore was detectable in isolate C but not in S2. The results of this study showed that these isolates had antifungal activities by production of siderophore and chitinase.

Sadeghi, A.

2006-01-01

162

Characterization of Mycorrhizal Isolates of Rhizoctonia solani from an Orchid, Including AG-12, a New Anastomosis Group.  

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ABSTRACT Isolates of Rhizoctonia solani collected from mycorrhizal orchid (Pterostylis acuminata) plants and adjacent leaf litter were characterized. Of 23 selected isolates, 20 were members of a new anastomosis group (AG-12) and the rest were members of AG-6. There were no bridging anastomosis reactions observed between AG-12 and other AGs of R. solani. Among the 20 isolates of AG-12 evaluated, 18 vegetatively compatible populations were detected, indicating diversity within the AG. Mature cultures were dark brown, as were mature sclerotia. Some cultures produced alternating dark- and light-colored concentric rings, with sclerotia forming in the darker rings. Most cultures were appressed to the agar surface. In tests run to characterize pathogenic potential, selected mycorrhizal isolates of AG-12 and AG-6 did little damage to potato and barley seedlings, moderate damage to head lettuce seedlings, and more extensive damage to seedlings of cauliflower and radish. Isolates of AG-12 have not been observed to fruit in nature, and all attempts to induce formation of the teleomorph (Thanatephorus cucumeris) in the laboratory by selected isolates of AG-12 failed. PMID:18944739

Carling, D E; Pope, E J; Brainard, K A; Carter, D A

1999-10-01

163

Effect of Certain Fungicides and Isolates of Antagonistic Fungi on Rhizoctonia solani, the Causal Agent of Rice Sheath Blight  

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Full Text Available Antagonistic fungi Trichoderma harzianum (T1, from bean fields in Ahwaz, T2, from rice fields in Rasht, T. viride (T3 from bean fields in Shahriar, T4 from the collection in Plant Pest and Disease Institute, Tehran, Gliocladium virens (from bean fields in Kamal Abad, Karaj and some fungicides (Benomyl, Carbendazim, Carboxin-Thiram, edifenphos and Zineb were used to control sheath blight of rice incited by Rhizoctonia solani in vitro and under greenhouse conditions. The experiment was carried out in a completely randomized design with 12 treatments and four replications on Khazar rice cultivar in a soil infected by R. solani under greenhouse conditions. The results showed that the antagonistic fungi reduce sheath blight by 19.8 (T1, 21.5 (T2, 27.5 (T3, 19.6 (T4 and 18.5 (G1 percent. The antagonistic fungi in order of efficacy were T2>T3>T1>T4>G1. Benomyl, Carbendazim, Carboxin-thiram, Edifenphos and Zineb reduced disease by 32.5, 21.5, 12.8, 9.5 and 0 percent, respectively. Statistical analysis of data indicated that there existed no significant differences between T1, T3, T4, and G1 and Carbendazim fungicide to control disease; however, the isolate T2 was as effective as Benomyl but Zineb had no effect on sheath blight.

S. A. Elahinia

2003-01-01

164

Potential for the integration of biological and chemical control of sheath blight disease caused by Rhizoctonia solani on rice.  

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Biological control using antagonistic microbes to minimize the use of chemical pesticides has recently become more prevalent. In an attempt to find an integrated control system for sheath blight, caused by Rhizoctonia solani in rice, Streptomyces philanthi RM-1-138, commercial formulations of Bacillus subtilis as Larminar® and B. subtilis strain NSRS 89-24+MK-007 as Biobest® and chemical fungicides including carbendazim®, validamycin®, propiconazole® and mancozeb® were applied alone and in combination with S. philanthi RM-1-138. In vitro experiments showed that all treatments tested did provide some control against mycelial growth and sclerotia production by R. solani PTRRS-9. In addition, the four chemical fungicides had no detrimental effects on S. philanthi RM-1-138 even at high concentrations (up to 100 ?g/ml). The efficacy of S. philanthi RM-1-138, the commercial formulations of B. subtilis, chemical fungicides alone or in combination with S. philanthi RM-1-138 was also tested in a greenhouse experiment against sheath blight disease on rice plants. All treatments showed some protection of rice for sheath blight by 47-60 % when carbendazim® was applied alone and up to 74 % when combined with S. philanthi RM-1-138. PMID:23653261

Boukaew, Sawai; Klinmanee, Chanasirin; Prasertsan, Poonsuk

2013-10-01

165

Efeito do tratamento de sementes de algodão com fungicidas no controle do tombamento de plântulas causado por Rhizoctonia solani  

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Full Text Available Este trabalho foi desenvolvido na Embrapa Agropecuária Oeste, em Dourados, MS, e teve por objetivo avaliar a eficiência de alguns fungicidas, aplicados no tratamento de sementes de algodão (Gossypium hirsutum, no controle do tombamento de plântulas causado por Rhizoctonia solani. Foi realizado teste em casa de vegetação, utilizando a cultivar DeltaOpal. Sementes tratadas e não tratadas com fungicidas foram semeadas em areia contida em bandejas plásticas, dispostas em orifícios individuais, eqüidistantes e a 3 cm de profundidade. A inoculação com R. solani foi feita pela distribuição homogênea do inóculo do fungo na superfície do substrato. O fungo foi cultivado por 35 dias em sementes de aveia autoclavadas e trituradas em moinho (1 mm. Foram utilizados 9 g de inóculo por bandeja de areia. Foi observado efeito do tratamento fungicida na emergência inicial e final de plântulas, com destaque para triadimenol + pencycuron + tolylfluanid e triadimenol + tolylfluanid, seguidos de carboxin + thiram, triadimenol e carboxin + thiram + carbendazim. Os tratamentos mais eficientes no controle do tombamento de pós-emergência do algodoeiro foi obtido com a mistura triadimenol + pencycuron + tolylfluanid, seguida de triadimenol, triadimenol + tolylfluanid e carboxin+thiram. Nenhum dos fungicidas testados foi fitotóxico ao algodão.

GOULART AUGUSTO C. P.

2002-01-01

166

Caracterización de aislamientos de Rhizoctonia Solani Kühn que inducen pudriciones radicales en cultivares de caraota (Phaseolus Vulgaris L.)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish Plántulas sintomáticas de caraota (Phaseolus vulgaris L.) fueron analizadas con objetivo de estudiar las pudriciones radicales inducidas por Rhizoctonia solani. Tres aislamientos identificados con las siglas CRH-V, CRH-F y CRH-558, que presentaban diferencias morfológicas entre sí, fueron utilizados [...] . Se evaluaron 18 cultivares de caraota. Se caracterizaron los grupos de anastomosis de R. solani asociados al cultivo y se determinó su patogenicidad. Los tres aislamientos sobre presentaron diferencias significativas con relación al crecimiento. Los aislamientos CRH-F y CRH-558 mostraron zonación. El aislamiento CRH-F formó esclerocios bajo luz artificial. Todos los aislamientos produjeron esclerocios bajo luz natural. En las reacciones hifales, los aislamientos CRH-F y CRH-558 produjeron solo contacto hifal con el patrón AG-1-1 y AG-4, respectivamente, y en el CRH-V no hubo interacción. Se detectaron diferencias significativas para el peso seco de las raíces y parte aérea entre cultivares, aislamientos e interacciones cultivar x aislamiento. Todos los aislamientos afectaron tanto el desarrollo radical como el aéreo en los cultivares evaluados. El aislamiento CRH-558 causó mayor disminución al peso seco en raíces y parte aérea. En las interacciones entre aislamientos y cultivares: MEX-E-62, Tacarigua y Victoria presentaron mayor peso seco de las raíces. Abstract in english Symptomatic black bean seedlings (Phaseolus vulgaris L) were analized in order to determine the root rot induced by R. solani. Three isolates of R. solani, which showed morphological differences were labeled with the acronyms CRH-V, CRH-F and CRH-558 and utilized. Eighteen beans cultivars were evalu [...] ated. Anastomosis groups of R. solani associated to the crop were characterized and their pathogenicity was determined. Significant differences in growth rate were found among the three isolates on PDA. The isolates CRH-F and CRH-558 showed zonation. The isolate CRH-F produced sclerotia under artificial light. Under natural light, all the isolates produced sclerotia. In hyphal reactions, the isolates CRH-F and CRH-558 showed only hyphal contact with AG-1-1 and AG-4, respectively. The isolate CRH-V showed no reaction. There were significant differences for the root and aerial part dry weight among cultivars, isolates and the interactions cultivars by isolates. The isolate CRH-558 caused higher reduction on dry weight and aerial part. In the interaction among isolates and cultivars, MEX -62, Tacarigua and Victoria showed higher root dry weight.

Bárbara, Gutiérrez; Maria Suleima, González; Alberto, Salih L.

167

Effects of methamidophos on the community structure, antagonism towards Rhizoctonia solani, and phlD diversity of soil Pseudomonas.  

Science.gov (United States)

A microcosm incubation study using an aquic brown soil from northeast China (a Cambisol in the UN Food and Agriculture Organization FAO Soil Taxonomy) was conducted to examine the effects of different concentrations (0, 50, 150, and 250 mg kg(-1)) of methamidophos (O,S-dimethyl phosphoramidothioato) on Pseudomonas, one of the most important gram-negative bacteria in soil. Amplified ribosomal DNA restriction analysis (ARDRA) was performed to study the Pseudomonas community structure, an in vitro assay was made to test the antagonistic activity of isolated Pseudomonas strains against soil-borne Rhizoctonia solani, a major member of the pathogens highly related to soil-borne plant diseases, and special primer amplification and sequencing were performed to investigate the diversity of phlD, an essential gene in the biosynthesis of 2, 4-diacetylphloroglucinol (2, 4-DAPG), which has biocontrol activity in phlD(+)isolates. With exposure to increasing methamidophos concentrations, the total number of soil Pseudomonas ARDRA patterns decreased significantly, but with less change in the same treatments over 1, 3, and 5 weeks of incubation. The number of isolated Pseudomonas strains with antagonistic activity against R. solani as well as the diversity and appearance frequency of the strains' phlD gene also decreased with increasing concentrations of methamidophos, especially at high methamidophos concentrations. Applying methamidophos could increase the risk of soil-borne plant diseases by decreasing the diversity of the soil Pseudomonas community and the amount of R. solani antagonists, particularly those with the phlD gene. PMID:20390954

Wu, Minna; Li, Xinyu; Zhang, Huiwen; Cai, Yinghui; Zhang, Chenggang

2010-04-01

168

The Interaction Pattern between a Homology Model of 40S Ribosomal S9 Protein of Rhizoctonia solani and 1-Hydroxyphenaize by Docking Study  

Science.gov (United States)

1-Hydroxyphenazine (1-OH-PHZ), a natural product from Pseudomonas aeruginosa strain SD12, was earlier reported to have potent antifungal activity against Rhizoctonia solani. In the present work, the antifungal activity of 1-OH-PHZ on 40S ribosomal S9 protein was validated by molecular docking approach. 1-OH-PHZ showed interaction with two polar contacts with residues, Arg69 and Phe19, which inhibits the synthesis of fungal protein. Our study reveals that 1-OH-PHZ can be a potent inhibitor of 40S ribosomal S9 protein of R. solani that may be a promising approach for the management of fungal diseases. PMID:24864254

Dharni, Seema; Sanchita; Sharma, Ashok; Patra, Dharani Dhar

2014-01-01

169

The interaction pattern between a homology model of 40S ribosomal S9 protein of Rhizoctonia solani and 1-hydroxyphenaize by docking study.  

Science.gov (United States)

1-Hydroxyphenazine (1-OH-PHZ), a natural product from Pseudomonas aeruginosa strain SD12, was earlier reported to have potent antifungal activity against Rhizoctonia solani. In the present work, the antifungal activity of 1-OH-PHZ on 40S ribosomal S9 protein was validated by molecular docking approach. 1-OH-PHZ showed interaction with two polar contacts with residues, Arg69 and Phe19, which inhibits the synthesis of fungal protein. Our study reveals that 1-OH-PHZ can be a potent inhibitor of 40S ribosomal S9 protein of R. solani that may be a promising approach for the management of fungal diseases. PMID:24864254

Dharni, Seema; Sanchita; Samad, Abdul; Sharma, Ashok; Patra, Dharani Dhar

2014-01-01

170

Identification of Rhizoctonia solani associated with soybean in Brazil by rDNA-ITS sequences Identificação de Rhizoctonia solani associada à soja no Brasil através de seqüências da região rDNA-ITS  

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Full Text Available The aim of this study was to identify isolates of Rhizoctonia solani causing hypocotyl rot and foliar blight in soybean (Glycine max in Brazil by the nucleotide sequences of ITS-5.8S regions of rDNA. The 5.8S rDNA gene sequence (155 bp was highly conserved among all isolates but differences in length and nucleotide sequence of the ITS1 and ITS2 regions were observed between soybean isolates and AG testers. The similarity of the nucleotide sequence among AG-1 IA isolates, causing foliar blight, was 95.1-100% and 98.5-100% in the ITS1 and ITS2 regions, respectively. The nucleotide sequence similarity among subgroups IA, IB and IC ranged from 84.3 to 89% in ITS1 and from 93.3 to 95.6% in ITS2. Nucleotide sequence similarity of 99.1% and 99.3-100% for ITS1 and ITS2, respectively, was observed between AG-4 soybean isolates causing hypocotyl rots and the AG-4 HGI tester. The similarity of the nucleotide sequence of the ITS-5.8S rDNA region confirmed that the R. solani Brazilian isolates causing foliar blight are AG-1 IA and isolates causing hypocotyl rot symptoms are AG-4 HGI. The ITS-5.8S rDNA sequence was not determinant for the identification of the AG-2-2 IIIB R. solani soybean isolate.O objetivo deste estudo foi identificar, através da seqüência de nucleotídeos das regiões ITS-5.8S do rDNA, isolados de Rhizoctonia solani causadores de podridão de hipocótilos e de queima foliar em soja (Glycine max, no Brasil. A seqüência do gene 5.8S do rDNA (155 bp foi altamente conservada entre todos os isolados, mas foram observadas diferenças no tamanho e na seqüência de nucleotídeos nas regiões ITS1 e ITS2 entre os isolados obtidos de soja e os padrões de grupos de anastomose (AGs. A similaridade na seqüência de nucleotídeos entre os isolados do AG-1 IA, causadores de queima foliar, foi 95,1-100% na região ITS1 e 98,5-100% na região ITS2. A similaridade na seqüência de nucleotídeos entre os subgrupos IA, IB e IC variaram de 84,3 a 89% no ITS1 e de 93,3 a 95,6% no ITS2. Entre os isolados obtidos de soja pertencentes ao AG-4 e o padrão AG-4 HGI foram observadas 99,1% e 99,3-100% de similaridades para ITS1 e ITS2, respectivamente. Foi possível confirmar através da análise das regiões ITS-5.8S do rDNA que os isolados de R. solani brasileiros, causadores de queima foliar são pertencentes ao AG-1 IA e que, os isolados causadores de podridão de hipocótilos pertencem ao AG-4 HGI. A análise das regiões ITS-5.8S do rDNA não foi determinante na identificação do isolado AG-2-2 IIIB obtido de soja.

Roseli C. Fenille

2003-08-01

171

Evaluation of chitinase activity in biological control process of rhizoctonia solani y fusarium oxysporum f. sp. lycopersici in tomate, by using seed priming in the presence of trichoderma koningii Evaluación de la actividad quitinasa en procesos de control biológico de rhizoctonia solani y fusarium oxysporum f. sp. lycopersici en tomate, mediante fitoinvigorización de semillas en presencia de trichoderma koningii  

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The present work intended to establish in a control model, the possible role of chitinases by using seed priming in the presence of Trichoderma koningii. This method showed to be efficient to control Rhizoctonia solani and Fusarium oxysporum in tomato. The analysis of seed extracts and e...

Cotes A. M.; Clavijo A.

1998-01-01

172

Relación entre la estructura de la comunidad bacteriana y la supresión al ahogamiento causado por Rhizoctonia solani en sustratos para plántulas de tomate  

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En este trabajo el objetivo fue estudiar la relación entre la supresión del ahogamiento causado por Rhizoctonia solani y la estructura de la comunidad bacteriana en sustratos orgánicos (con base en vermicomposta y composta), para el crecimiento de plántulas de tomate. Dicha estructura comunitaria se determinó mediante T-RFLP (Terminal Restriction Fragment Length Polymorphisms) del gen ARNr 16S, con la enzima Hin6I. Análisis de componentes principales (PCA) a partir de las abundancias re...

Robledo, O.; Etchebehere, C.; Lercari, D.

2010-01-01

173

Severidade da mela da soja causada por Rhizoctonia solani AG-1 IA em função de doses de potássio Severity of hte foliar blight of the soylean caused by Rhizoctonia solani AG-1 IA infunction of doses of potassium  

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Full Text Available O fungo Rhizoctonia solani pertencente ao grupo de anastomose 1 IA (AG-1 IA é um dos patógenos mais importantes afetando a cultura da soja no Brasil. Este fungo causa queima da folha e/ou mela em soja, para a qual medidas de manejo cultural são consideradas alternativas importantes para controle antes do estabelecimento da doença. Há evidências de que a adubação potássica diminui substancialmente a severidade dos sintomas de várias doenças da soja como a queima foliar (Cercospora kikuchii, a seca da haste e da vagem (Phomopsis phaseoli var. sojae e o cancro da haste (Diaporthe phaseolorum f. sp. meridionalis. Apesar das evidências do efeito do potássio no controle de várias doenças da soja, não há informação na literatura sobre o efeito desse nutriente no controle da mela. A hipótese testada foi que a mela da soja pode ser controlada através de incrementos na adubação potássica. De maneira geral, concluiu-se que, sob condições de casa de vegetação, o incremento de K no solo não resultou no controle da mela da soja. É necessário, entretanto, confirmar esta observação conduzindo-se experimentos sob condições de campo, podendo-se incluir a avaliação do efeito da doença sob aspectos da produção.The fungus Rhizoctonia solani, belonging to anastomosis group 1IA (AG-1 IA is one of the most important pathogens affecting soybean in Brazil. This fungus causes aerial or foliar blight of soybean, and cultural measures are thought as important choices for the control before the establishment of the disease. Based on evidences that potassium amendments can substantially reduce the severity of several soybean diseases such as Cercospora leaf blight (Cercospora kikuchii, pod and stem blight (Phomopsis phaseoli var. sojae and stem canker (Diaporthe phaseolorum f. sp. meridionalis. Despite all evidence, there is no information in the literature about the effect of potassium controlling the soybean foliar blight. The hypothesis tested went that the foliar blight could be controlled by potassium amendments. In general, under controlled conditions, the increments of potassium in soil did not result in disease control. Therefore, to corroborate this observation it is necessary to conduct follow-up field experiments and to evaluate the effects of the soybean foliar blight and its impact on yield.

Marco Antonio Basseto

2007-03-01

174

Severidade da mela da soja causada por Rhizoctonia solani AG-1 IA em função de doses de potássio / Severity of hte foliar blight of the soylean caused by Rhizoctonia solani AG-1 IA infunction of doses of potassium  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O fungo Rhizoctonia solani pertencente ao grupo de anastomose 1 IA (AG-1 IA) é um dos patógenos mais importantes afetando a cultura da soja no Brasil. Este fungo causa queima da folha e/ou mela em soja, para a qual medidas de manejo cultural são consideradas alternativas importantes para controle an [...] tes do estabelecimento da doença. Há evidências de que a adubação potássica diminui substancialmente a severidade dos sintomas de várias doenças da soja como a queima foliar (Cercospora kikuchii), a seca da haste e da vagem (Phomopsis phaseoli var. sojae) e o cancro da haste (Diaporthe phaseolorum f. sp. meridionalis). Apesar das evidências do efeito do potássio no controle de várias doenças da soja, não há informação na literatura sobre o efeito desse nutriente no controle da mela. A hipótese testada foi que a mela da soja pode ser controlada através de incrementos na adubação potássica. De maneira geral, concluiu-se que, sob condições de casa de vegetação, o incremento de K no solo não resultou no controle da mela da soja. É necessário, entretanto, confirmar esta observação conduzindo-se experimentos sob condições de campo, podendo-se incluir a avaliação do efeito da doença sob aspectos da produção. Abstract in english The fungus Rhizoctonia solani, belonging to anastomosis group 1IA (AG-1 IA) is one of the most important pathogens affecting soybean in Brazil. This fungus causes aerial or foliar blight of soybean, and cultural measures are thought as important choices for the control before the establishment of th [...] e disease. Based on evidences that potassium amendments can substantially reduce the severity of several soybean diseases such as Cercospora leaf blight (Cercospora kikuchii), pod and stem blight (Phomopsis phaseoli var. sojae) and stem canker (Diaporthe phaseolorum f. sp. meridionalis). Despite all evidence, there is no information in the literature about the effect of potassium controlling the soybean foliar blight. The hypothesis tested went that the foliar blight could be controlled by potassium amendments. In general, under controlled conditions, the increments of potassium in soil did not result in disease control. Therefore, to corroborate this observation it is necessary to conduct follow-up field experiments and to evaluate the effects of the soybean foliar blight and its impact on yield.

Marco Antonio, Basseto; Paulo Cezar, Ceresini; Walter Veriano, Valério Filho.

175

Biotic and abiotic factors associated with soil suppressiveness to Rhizoctonia solani  

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Full Text Available Crop management may modify soil characteristics, and as a consequence, alter incidence of diseases caused by soilborne pathogens. This study evaluated the suppressiveness to R. solani in 59 soil samples from a microbasin. Soil sampling areas included undisturbed forest, pasture and fallow ground areas, annual crops, perennial crops, and ploughed soil. The soil samples were characterized according to abiotic variables (pH; electrical conductivity; organic matter content; N total; P; K; Ca; Mg; Al; H; S; Na; Fe; Mn; Cu; Zn; B; cation exchange capacity; sum of bases and base saturation and biotic variables (total microbial activity evaluated by the CO2 evolution and fluorescein diacetate hydrolysis; culturable bacterial, fungal, actinomycetes, protozoa, fluorescent Pseudomonas and Fusarium spp. communities. The contribution and relationships of these variables to suppression to R. solani were assessed by path analysis. When all samples were analyzed together, only abiotic variables correlated with suppression of R. solani, but the entire set of variables explained only 51% of the total variation. However, when samples were grouped and analyzed by vegetation cover, the set of evaluated variables in all cases accounted for more than 90% of the variation in suppression of the pathogen. In highly suppressive soils of forest and pasture/fallow ground areas, several abiotic variables and fluorescein diacetate hydrolysis correlated with suppression of R. solani and the set of variables explained more than 98% of suppressiveness.

Ghini Raquel

2006-01-01

176

Effect of Combined Use of Bacillus subtilis CA32 and Trichoderma harzianum RU01 on Biological Control of Rhizoctonia solani on Solanum melongena and Capsicum annuum  

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Full Text Available A combination of two compatible biological control agents, Bacillus subtilis CA32 and Trichoderma harzianum RU01, both antagonistic to the pathogen Rhizoctonia solani, was used to control damping-off in Solanum melongena and Capsicum annuum. Radial growth of the mycelium of R. solani was inhibited by T. harzianum RU01 in dual Petri plate assay. T. harzianum RU01 was capable to invading the whole surface of the pathogen colony, sporulating on it and suppress the production of sclerotia of R. solani. Microscopic studies showed the hyphae of R. solani surrounded by the T. harzianum RU01 and subsequent disintegration. B. subtilis CA32 produced a zone of inhibition only with the pathogen and no sings of antagonism between the bacteria and T. harzianum RU01 on dual Petri plate assay. Significant plant protection was achieved when either B. subtilis added to the seeds or T. harzianum added to soil. However, when combine application of biocontrol agents, seed bacterization and T. harzianum application to soil, significantly enhanced the plant protection from R. solani. Soil application of B. subtilis and seed application of T. harzianum either singly or in combination did not protect from R. solani infection indicating that the importance of mode of application of biocontrol agents.

S. Abeysinghe

2009-01-01

177

Use of Pseudomonas aeruginosa in the control od root-knot disease complex in tomato: the effects of different inoculum levels of Meloidogyne javanica and Rhizoctonia solani  

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Full Text Available The potential impact of Pseudomons aeruginosa strain IE-6 as a biological control agent against Meloidogyne javanica at four inoculum densities (0, 250, 500 and 1000 eggs/plant and Rhizoctonia solani at three inoeulum levels (0, 1 and 3 ml culture suspension/kg of soil was examined on tomato in the greenhouse experiments. The biocontrol bacterium suppressed root infection caused by R. solani and M. javanica on tomato in both sterilized and non-sterilized soils. Root-rot infection increased with the increase in pathogen(s concentration. P. aeruginosa showed better biocontrol effects at low population levels of M.javanica and R. solani than at higher population densities of the pathogen(s. Root-rot disease severity was more pronounced in sterilized soil compared to the non-sterilized one. Soil infested with high population densities ofR. solani (3 ml /kg of soil and M. javanica (2000 eggs/pot resulted in complete mortality of tomato seedlings in sterilized soil, whereas some plants were found to survive in non-stenlized soil. There seems to be a correlation between population density of M. javanica and root colonization by R. solani. Root colonization by other three root-infecting fungi including Macrophomina phaseolina, Fusarium oxysporum and Fusarium solani was also lower in the presence of P. aeruginosa in non-sterilized soil. P. aeruginosa enhanced plant growth in both types of soil.

I. A. Siddiqui

2001-06-01

178

Caracterização citomorfológica, cultural, molecular e patogênica de Rhizoctonia solani Kühn associado ao arroz em Tocantins, Brasil Citomorphological, cultural, molecular and pathogenical characterization of Rhizoctonia solani Kühn associated with rice in Tocantins, Brazil  

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Full Text Available No Estado do Tocantins, no Norte do Brasil, a incidência de rizoctoniose no arroz é importante, causando danos significativos em lavouras de arroz irrigado. O principal objetivo deste trabalho foi determinar o grupo de anastomose (AG de isolados de R. solani associados ao arroz naquela região, testando a hipótese de que esses isolados pertencem ao grupo padrão de anastomose AG-1 IA, que também é o agente causal da mela em soja em áreas úmidas do Norte do Brasil. Todos os quatro isolados de arroz foram caracterizados, através de fusão de hifas, como AG-1 IA. A caracterização cultural, em função das temperaturas basais (mínimas, máximas e ótimas, evidenciou que os isolados de R. solani de arroz apresentaram perfis semelhantes aos padrões AG-1 IA, AG-1 IB e AG-1 IC. Os isolados de arroz foram caracterizados como autotróficos para tiamina assim como os isolados padrões AG-1 IA, IB, IC, AG-4 HGI e o isolado da mela da soja. O teste de patogenicidade em plantas de arroz cultivar IRGA-409 e de patogenicidade cruzada à cultivar IAC-18 de soja (suscetível à mela, indicou que além de causar a queima da bainha em arroz, esses isolados causam mela em soja. Da mesma forma, o isolado SJ-047 foi patogênico ao arroz. As seqüências de bases de DNA da região ITS-5.8S do rDNA dos isolados do arroz foram similares às seqüências do AG-1 IA, depositadas no GenBank® - NCBI. A filogenia do ITS-rDNA indicou um grupo filogenético comum formado pelos isolados do arroz, o isolado da soja e o isolado teste do AG-1 IA. Assim, com base em características citomorfológicas, culturais, filogenéticas e patogênicas, foi confirmada a hipótese de que os isolados de R. solani patógenos de arroz do Estado do Tocantins pertencem ao grupo de anastomose AG-1 IA, além da indicação de que esses isolados podem também causar a mela em soja.In Tocantins State, Northern Brazil, the incidence of Rhizoctonia sheath blight on rice is important, causing significant yield losses on rice crops under irrigation. The main objective of this research was to determine the anastomosis group (AG of R. solani associated with rice in that area, testing the hypothesis that these isolates are from the AG-1 IA, which is also associated with the soybean leaf blight occurring in wet areas of Northern Brazil. All the four rice isolates were characterized, by hyphal fusion, as AG-1 IA. By cultural characterization, based on basal temperatures for mycelial growth (minimum, optimum and maximum, the rice isolates had growth profile similar to the tester isolates AG-1 IA, AG-1 IB and AG-1 IC. The rice isolates were characterized as autotrophic for thiamine, as well as the AG testers AG-1 IA, IB, IC, AG-4 HGI and the soybean leaf blight isolate SJ-047. The pathogenicity test on rice IRGA-409 and the cross pathogenicity on soybean IAC-18 (susceptible to the leaf blight disease indicated that, besides causing sheath blight, these rice isolates also cause leaf blight on soybean. Similarly, the soybean isolates SJ-047 was pathogenic to rice. The sequences from the ITS-5.8S region of rDNA from the rice isolates were similar to sequences of AG-1 IA deposited at GenBank® - NCBI. The ITS-rDNA phylogeny indicated a common phylogenetic group formed by these rice isolates, the isolate SJ-047 and the tester AG-1 IA. Thus, based on cytomorphological, cultural, phylogenetics and pathogenic attributes, the hypothesis that the rice isolates of R. solani from Tocantins all belong to the AG-1 IA was confirmed, besides the indication that these isolates can also cause soybean foliar blight.

Elaine Costa Souza

2007-06-01

179

Lippia graveolens and Carya illinoensis Organic Extracts and there in vitro Effect Against Rhizoctonia Solani Kuhn  

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Full Text Available Problem statement: Plant extracts with polyphenolic compounds obtained with different solvents have been evaluated against plant pathogens. However, most of these extract have been obtained using solvents no allowed under an organic production context. Approach: In the present research was to evaluate the inhibitory effect of polyphenolic extracts from L. graveolens and C. illinoensis, obtained with alternative organic solvents (lanolin and cocoa butter, water and ethanol against R. solani in order to determine the Inhibitory Concentration (IC50 of each extract. Results: The results showed that extracts of both L. graveolens and C. illinoensis obtained with lanolin and ethanol (200 and 3000 ppm of total tannins, respectively inhibited at 100% growth of R. solani. The IC50 for each extract was highly variable, low IC50 values were obtained with L. graveolens (4.50×101 and C. illinoensis (4.33×102 extract using lanolin and ethanol respectively. Tannins extraction was strongly dependent on plant species and in the solvent used. Conclusion: The alternative organic solvents lanolin and cocoa butter allowed the recovery of polyphenols compounds with antifungal activity against R. solani.

Francisco D. Hernandez-Castillo

2010-01-01

180

Wheat Genotype-Specific Induction of Soil Microbial Communities Suppressive to Disease Incited by Rhizoctonia solani Anastomosis Group (AG)-5 and AG-8.  

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ABSTRACT The induction of disease-suppressive soils in response to specific cropping sequences has been demonstrated for numerous plant-pathogen systems. The role of host genotype in elicitation of the essential transformations in soil microbial community structure that lead to disease suppression has not been fully recognized. Apple orchard soils were planted with three successive 28-day cycles of specific wheat cultivars in the greenhouse prior to infestation with Rhizoctonia solani anastomosis group (AG)-5 or AG-8. Suppressiveness to Rhizoctonia root rot of apple caused by the introduced isolate of R. solani AG-5 was induced in a wheat cultivar-specific manner. Pasteurization of soils after wheat cultivation and prior to pathogen introduction eliminated the disease suppressive potential of the soil. Wheat cultivars that induced disease suppression enhanced populations of specific fluorescent pseudomonad genotypes with antagonistic activity toward R. solani AG-5 and AG-8, but cultivars that did not elicit a disease suppressive soil did not modify the antagonistic capacity of this bacterial community. When soils were infested prior to the initial wheat planting, all cultivars were uniformly susceptible to R. solani AG-8. However, when pathogen inoculum was added after three growth-cycles, wheat root infection during the fourth growth-cycle varied in a cultivar specific manner. The same wheat cultivar-specific response in terms of transformation of the fluorescent pseudomonad community and subsequent suppression of Rhizoctonia root rot of apple was observed in three different orchard soils. These results demonstrate the importance of host genotype in modification of indigenous saprophytic microbial communities and suggest an important role for host genotype in the success of biological control. PMID:18943884

Mazzola, Mark; Gu, Yu-Huan

2002-12-01

 
 
 
 
181

Interplay between parasitism and host ontogenic resistance in the epidemiology of the soil-borne plant pathogen Rhizoctonia solani.  

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Spread of soil-borne fungal plant pathogens is mainly driven by the amount of resources the pathogen is able to capture and exploit should it behave either as a saprotroph or a parasite. Despite their importance in understanding the fungal spread in agricultural ecosystems, experimental data related to exploitation of infected host plants by the pathogen remain scarce. Using Rhizoctonia solani / Raphanus sativus as a model pathosystem, we have obtained evidence on the link between ontogenic resistance of a tuberizing host and (i) its susceptibility to the pathogen and (ii) after infection, the ability of the fungus to spread in soil. Based on a highly replicable experimental system, we first show that infection success strongly depends on the host phenological stage. The nature of the disease symptoms abruptly changes depending on whether infection occurred before or after host tuberization, switching from damping-off to necrosis respectively. Our investigations also demonstrate that fungal spread in soil still depends on the host phenological stage at the moment of infection. High, medium, or low spread occurred when infection was respectively before, during, or after the tuberization process. Implications for crop protection are discussed. PMID:25127238

Simon, Thomas E; Le Cointe, Ronan; Delarue, Patrick; Morlière, Stéphanie; Montfort, Françoise; Hervé, Maxime R; Poggi, Sylvain

2014-01-01

182

Responses of 2 epiphytic yeasts to foliar infection by Rhizoctonia solani or mechanical wounding on the phylloplane of tall fescue.  

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A growth-chamber experiment was conducted to determine how foliar disease or wounding affects the ability of 2 phylloplane yeasts (Rhodotorula glutinis and Cryptococcus laurentii) to colonize leaves of tall fescue (Festuca arundinacea). Yeasts were applied separately and together onto healthy leaves, leaves infected with Rhizoctonia solani (diseased), and mechanically bruised (wounded) leaves. In all 3 trials, the leaf disturbance treatment significantly affected the abundance of yeast on the phylloplane of tall fescue. Yeast abundance on the diseased or wounded leaves was significantly greater than on the nontreated, healthy leaves. In 2 of the 3 trials, the yeast species applied also had a significant affect on yeast abundance. Typically, R. glutinis was significantly more abundant than C. laurentii when applied individually, but not significantly greater than the total yeast colony-forming units of the co-inoculated treatment. When the 2 yeasts were co-inoculated onto the leaves, R. glutinis comprised 89.7%, 75.4%, and 67.6% of the recovered yeast colony-forming units on healthy, diseased, and wounded leaves, respectfully. Our data suggest that these 2 species of yeasts will differentially colonize compromised leaf tissue with disease or wounds favoring populations of R. glutinis over C. laurentii. PMID:19935888

Nix, Shannon; Burpee, Leon L; Buck, James W

2009-10-01

183

Silício alterando compostos derivados da pirólise de bainhas foliares de plantas de arroz infectadas por Rhizoctonia solani / Silicon altering compounds derived from the pyrolyses of leaf sheaths of rice plants infected with Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho teve como objetivo elucidar, por meio da pirólise analítica acoplada à cromatografia gasosa e espectrometria de massa, alterações na composição química da lignina nas bainhas de plantas de arroz das cultivares BR-Irga 409 e Labelle supridas ou não com silício (Si) e infectadas por Rhiz [...] octonia solani. A concentração de Si nas bainhas das plantas supridas com esse elemento foi significativamente maior (2,7 dag kg-1) em comparação com as plantas não supridas (0,45 dag kg-1). Na presença de Si, a área abaixo da curva do progresso da queima das bainhas foi significativamente reduzida em 19 e 25%, respectivamente, para as plantas das cultivares BR-Irga-409 e Labelle em relação à ausência desse elemento na solução nutritiva. Com base nos espectros de massas obtidos, foram identificados 33 compostos, dos quais 10 foram produtos da degradação de carboidratos e 23 derivados da lignina. Dentre os derivados da lignina, oito compostos eram do tipo p-hidroxifenila, 11 compostos do tipo guaiacila e quatro compostos do tipo siringila. Nas bainhas das plantas das duas cultivares de arroz, supridas ou não com Si, a concentração de lignina (p-hidroxifenila, siringila (S) e guaiacila (G)) foi de, aproximadamente, 15%. Houve aumento na relação S/G apenas nas bainhas das plantas da cultivar BR-Irga 409 supridas com Si e infectadas por R. solani. A maior concentração de Si nas bainhas das plantas de arroz das duas cultivares, que por sua vez resultou em aumento na relação S/G, contribuiu para reduzir os sintomas da queima das bainhas. Abstract in english This study elucidated, through analytical pyrolysis coupled to gas chromatography and mass spectrometry, changes in the chemical composition of lignin on leaf sheaths of rice plants of cultivars BR-Irga 409 and Labelle supplied or non-supplied with silicon (Si) and infected with Rhizoctonia solani. [...] The Si concentration on leaf sheaths of plants supplied with this element was significatively higher (2.7 dag kg-1) as compared to non-supplied plants (0.45 dag kg-1). In the presence of Si, the area under leaf sheath blight progress curve was significantly reduced by 19 and 25% for plants from cultivars BR-Irga 409 and Labelle, respectively, in comparison to the absence of Si. Based on the mass spectra obtained, 33 compounds were identified, 10 of which were products from the degradation of carbohydrates and 23 derivate from lignin. From lignin derivatives, eight compounds were p-hydroxiphenil type, eleven compounds were guaiacyl type and four compounds were syringyl type. On leaf sheaths of both cultivars, the concentration of lignin (p-hydroxiphenil, syringyl (S) and guaiacyl (G)) was around 15%, regardless of Si. There was no increase in the S/G ratio only for the leaf sheaths of BR-Irga 409 supplied with Si and infected with R. solani. High Si concentration on leaf sheaths of both cultivars, which in turn resulted in an increase in the S/G ratio, contributed to reduce leaf sheath blight symptoms.

Daniel Augusto, Schurt; Fabrício Ávila, Rodrigues; Vivian, Carré-Missio; Nilda Fátima Ferreira, Soares.

184

Silício alterando compostos derivados da pirólise de bainhas foliares de plantas de arroz infectadas por Rhizoctonia solani / Silicon altering compounds derived from the pyrolyses of leaf sheaths of rice plants infected with Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho teve como objetivo elucidar, por meio da pirólise analítica acoplada à cromatografia gasosa e espectrometria de massa, alterações na composição química da lignina nas bainhas de plantas de arroz das cultivares BR-Irga 409 e Labelle supridas ou não com silício (Si) e infectadas por Rhiz [...] octonia solani. A concentração de Si nas bainhas das plantas supridas com esse elemento foi significativamente maior (2,7 dag kg-1) em comparação com as plantas não supridas (0,45 dag kg-1). Na presença de Si, a área abaixo da curva do progresso da queima das bainhas foi significativamente reduzida em 19 e 25%, respectivamente, para as plantas das cultivares BR-Irga-409 e Labelle em relação à ausência desse elemento na solução nutritiva. Com base nos espectros de massas obtidos, foram identificados 33 compostos, dos quais 10 foram produtos da degradação de carboidratos e 23 derivados da lignina. Dentre os derivados da lignina, oito compostos eram do tipo p-hidroxifenila, 11 compostos do tipo guaiacila e quatro compostos do tipo siringila. Nas bainhas das plantas das duas cultivares de arroz, supridas ou não com Si, a concentração de lignina (p-hidroxifenila, siringila (S) e guaiacila (G)) foi de, aproximadamente, 15%. Houve aumento na relação S/G apenas nas bainhas das plantas da cultivar BR-Irga 409 supridas com Si e infectadas por R. solani. A maior concentração de Si nas bainhas das plantas de arroz das duas cultivares, que por sua vez resultou em aumento na relação S/G, contribuiu para reduzir os sintomas da queima das bainhas. Abstract in english This study elucidated, through analytical pyrolysis coupled to gas chromatography and mass spectrometry, changes in the chemical composition of lignin on leaf sheaths of rice plants of cultivars BR-Irga 409 and Labelle supplied or non-supplied with silicon (Si) and infected with Rhizoctonia solani. [...] The Si concentration on leaf sheaths of plants supplied with this element was significatively higher (2.7 dag kg-1) as compared to non-supplied plants (0.45 dag kg-1). In the presence of Si, the area under leaf sheath blight progress curve was significantly reduced by 19 and 25% for plants from cultivars BR-Irga 409 and Labelle, respectively, in comparison to the absence of Si. Based on the mass spectra obtained, 33 compounds were identified, 10 of which were products from the degradation of carbohydrates and 23 derivate from lignin. From lignin derivatives, eight compounds were p-hydroxiphenil type, eleven compounds were guaiacyl type and four compounds were syringyl type. On leaf sheaths of both cultivars, the concentration of lignin (p-hydroxiphenil, syringyl (S) and guaiacyl (G)) was around 15%, regardless of Si. There was no increase in the S/G ratio only for the leaf sheaths of BR-Irga 409 supplied with Si and infected with R. solani. High Si concentration on leaf sheaths of both cultivars, which in turn resulted in an increase in the S/G ratio, contributed to reduce leaf sheath blight symptoms.

Daniel Augusto, Schurt; Fabrício Ávila, Rodrigues; Vivian, Carré-Missio; Nilda Fátima Ferreira, Soares.

2013-03-01

185

Phylogeography of the Solanaceae-infecting Basidiomycota fungus Rhizoctonia solani AG-3 based on sequence analysis of two nuclear DNA loci  

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Full Text Available Abstract Background The soil fungus Rhizoctonia solani anastomosis group 3 (AG-3 is an important pathogen of cultivated plants in the family Solanaceae. Isolates of R. solani AG-3 are taxonomically related based on the composition of cellular fatty acids, phylogenetic analysis of nuclear ribosomal DNA (rDNA and beta-tubulin gene sequences, and somatic hyphal interactions. Despite the close genetic relationship among isolates of R. solani AG-3, field populations from potato and tobacco exhibit comparative differences in their disease biology, dispersal ecology, host specialization, genetic diversity and population structure. However, little information is available on how field populations of R. solani AG-3 on potato and tobacco are shaped by population genetic processes. In this study, two field populations of R. solani AG-3 from potato in North Carolina (NC and the Northern USA; and two field populations from tobacco in NC and Southern Brazil were examined using sequence analysis of two cloned regions of nuclear DNA (pP42F and pP89. Results Populations of R. solani AG-3 from potato were genetically diverse with a high frequency of heterozygosity, while limited or no genetic diversity was observed within the highly homozygous tobacco populations from NC and Brazil. Except for one isolate (TBR24, all NC and Brazilian isolates from tobacco shared the same alleles. No alleles were shared between potato and tobacco populations of R. solani AG-3, indicating no gene flow between them. To infer historical events that influenced current geographical patterns observed for populations of R. solani AG-3 from potato, we performed an analysis of molecular variance (AMOVA and a nested clade analysis (NCA. Population differentiation was detected for locus pP89 (?ST = 0.257, significant at P ST = 0.034, not significant. Results based on NCA of the pP89 locus suggest that historical restricted gene flow is a plausible explanation for the geographical association of clades. Coalescent-based simulations of genealogical relationships between populations of R. solani AG-3 from potato and tobacco were used to estimate the amount and directionality of historical migration patterns in time, and the ages of mutations of populations. Low rates of historical movement of genes were observed between the potato and tobacco populations of R. solani AG-3. Conclusion The two sisters populations of the basidiomycete fungus R. solani AG-3 from potato and tobacco represent two genetically distinct and historically divergent lineages that have probably evolved within the range of their particular related Solanaceae hosts as sympatric species.

Vilgalys Rytas J

2007-09-01

186

EFFICACY OF BIOCONTROL AGENTS IN CONTROLLING RHIZOCTONIA SOLANI ON NAGA KING CHILLI ( Capsicum chinense Jacq.  

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Full Text Available Available biocontrol agents were evaluated either alone or in various combinations for finding out their efficacy in suppressing Rhizoctonia seedling rot incidence and promoting plant growth of Naga king chilli (Capsicum chinense Jacq. in green house as well field conditions. Among all tested combination, the treatment containing combination of T. viride +P. fluorescens was found most effective in reducing the incidence of seedling rot in both greenhouse and field condition. Highest per plant yield was also recorded from the same combination and it was followed by T. viride. However, the commercially available fungicide Copper oxychloride (0.1% showed 9.82 % and11.88% disease incidence in greenhouse and field condition respectively

Marinus Ngullie

2013-07-01

187

Modulation of the phenylacetic acid metabolic complex by quinic acid alters the disease-causing activity of Rhizoctonia solani on tomato.  

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The metabolic control of plant growth regulator production by the plant pathogenic fungus Rhizoctonia solani Kühn (teleomorph=Thanatephorus cucumeris (A.B. Frank) Donk) and consequences associated with the parasitic and saprobic activity of the fungus were investigated. Fourteen genetically distinct isolates of the fungus belonging to anastomosis groups (AG) AG-3, AG-4, and AG-1-IA were grown on Vogel's minimal medium N with and without the addition of a 25 mM quinic acid (QA) source of carbon. The effect of QA on fungal biomass was determined by measuring the dry wt of mycelia produced under each growth condition. QA stimulated growth of 13 of 14 isolates of R. solani examined. The production of phenylacetic acid (PAA) and the chemically related derivatives 2-hydroxy-PAA, 3-hydroxy-PAA, 4-hydroxy-PAA, and 3-methoxy-PAA on the two different media was compared by gas chromatography coupled with mass spectrometry (GC-MS). The presence of QA in the growth medium of R. solani altered the PAA production profile, limiting the conversion of PAA to derivative forms. The effect of QA on the ability of R. solani to cause disease was examined by inoculating tomato (Solanum lycopersicum L.) plants with 11 isolates of R. solani AG-3 grown on media with and without the addition of 25 mM QA. Mean percent survival of tomato plants inoculated with R. solani was significantly higher when the fungal inoculum was generated on growth medium containing QA. The results of this study support the hypotheses that utilization of QA by R. solani leads to reduced production of the plant growth regulators belonging to the PAA metabolic complex which can suppress plant disease development. PMID:23380633

Bartz, Faith E; Glassbrook, Norman J; Danehower, David A; Cubeta, Marc A

2013-05-01

188

Bioprospecção de isolados de Trichoderma spp. para o controle de Rhizoctonia solani na produção de mudas de pepino / Bioprospection of Trichoderma spp. isolates to control Rhizoctonia solani on cucumber seedling production  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi selecionar e identificar isolados de Trichoderma spp. para o controle do tombamento causado por Rhizoctonia solani (AG-4) em plântulas de pepino (Cucumis sativus L.), além de avaliar o efeito de concentrações crescentes e de combinações dos isolados mais eficientes no c [...] ontrole da doença. Os experimentos foram conduzidos em casa de vegetação, com 490 isolados. O tombamento das mudas foi avaliado uma semana após a aplicação à base das plântulas de substrato infestado com antagonista (1%) e patógeno (1%). Os doze isolados que proporcionaram mais de 85% de redução da doença foram testados em concentrações crescentes para o controle do patógeno (1%): 0,5, 1, 2, 3 e 4%. Também foi avaliado o efeito das combinações dos cinco isolados mais promissores. Os isolados mais efetivos foram identificados pelo sequenciamento da região espaçadores internos transcritos (ITS) do DNA ribossômico. Dos 490 isolados testados 44 (9%) reduziram o tombamento. As concentrações de antagonistas superiores a 2% foram as mais efetivas no controle da doença. Apenas duas combinações resultaram no aumento do controle da doença. Os isolados mais efetivos foram identificados como T. hamatum (IB08, IB30, IB60), T. harzianum (IB34, IB35), T. atroviride (IB13), T. spirale (IB16, IB24) e T. asperellum (IB44). Não foi possível a identificação da espécie de três isolados. Abstract in english The objective of this work was to select and identify Trichoderma spp. isolates for the control of Rhizoctonia solani (AG-4) damping-off on cucumber (Cucumis sativus L.) seedlings, as well as to evaluate the effects of increasing concentrations and different combinations of the most efficient isolat [...] es in the disease control. The experiments were carried out in a greenhouse with 490 isolates. The disease on cucumber seedlings was evaluated one week after the application of a commercial substrate infested with both antagonist (1%) and pathogen (1%) to the seedlings' root collar. The twelve isolates that conferred more than 85% of disease reduction were further evaluated in pathogen control (1%) at the concentrations 0.5, 1, 2, 3 and 4%. The effect of combining five of the most promising isolates in disease control was also evaluated. The most effective isolates were identified through the sequencing of the ribosomal internal transcribed spacers (ITS) region. Out of the 490 isolates tested 44 (9%) caused reduction of damping-off. Antagonist concentrations higher than 2% conferred the most effective disease control. Only two combinations of isolates resulted in increased disease control. The most effective isolates were identified as T. hamatum (IB08, IB30, IB60), T. harzianum (IB34, IB35), T. atroviride (IB13), T. spirale (IB16, IB24) and T. asperellum (IB44). Three isolates could not be identified at species level.

Cleusa Maria Mantovanello, Lucon; Claudia Mitsue, Koike; Alice Ishida, Ishikawa; Flávia Rodrigues Alves, Patrício; Ricardo, Harakava.

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Control del mal de los almácigos causado por Rhizoctonia solani y Sclerotium rolfsii con caldos de cebolla / Control of seedling damping off caused by Rhizoctonia solani and Sclerotium rolfsii using onion broths  

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Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish El mal de los almácigos causa muerte de plántulas. Los controles cultural y biológico constituyen las únicas herramientas orgánicas para su manejo. Acerca de la eficiencia de preparaciones vegetales, sólo se encuentra información de divulgación. Este trabajo evalúa el efecto de caldos fermentados de [...] cebolla sobre el crecimiento de Rhizoctonia solani y Sclerotium rolfsii y la incidencia de la enfermedad. Se obtuvieron caldo (B) y caldo esterilizado (SB), respectivamente, mediante hervido de trozos de cebollas y fermentación a temperatura ambiente, con o sin esterilización posterior. Se cultivaron los patógenos en APG suplementado con B y SB diluidos 1,7; 3,3; 8,3; 16,7 y 25%. Su crecimiento decreció con B al 8,3, 16,7 y 25%. La producción de esclerocios por S. rolfsii disminuyó con B, pero aumentó con SB. Penicillium purpurogenum, P. simplicissimum y Aspergillus niger aislados de B evidenciaron antibiosis, competencia e hiperparasitismo respecto de ambos patógenos. B y SB diluidos 10 y 50% fueron aplicados en almácigos de acelga (Beta vulgaris), tomate (Solanum lycopersicum), pimiento (Capsicum annuum) y berenjena (Solanum melongena) infestados. La pérdida de plántulas fue menor en el tratamiento con B al 50%, en relación al tratamiento con SB. Se concluye que la actividad antifúngica de B depende de su dilución y de su micota. La utilización de caldos de cebolla debería ser contemplada como alternativa para el manejo fitosanitario de bajo impacto ambiental. Se requiere continuar los estudios para completar el conocimiento acerca de los componentes químicos y microbiológicos de los caldos, y sus posibles cambios durante la fermentación. Abstract in english Damping off is a frequent disease that kills seedlings. Cultural and biological controls are the only tools in organic crops to manage this disease, and only empirical information is available on the eficiency of plant preparations. This work evaluates the effects of fermented onion decoctions on th [...] e growth of Rhizoctonia solani and Sclerotium rolfsii and disease incidence. Broth (B) and sterilized broth (SB) were respectively obtained by boiling chopped yellow onions in water, and incubating for 14 days at room temperature, with or without subsequent sterilization. The pathogens were grown on potato dextrose agar supplemented with B and SB, diluted at 1.7, 3.3, 8.3, 16.7 and 25% (v/v). Their growth was reduced by B at 8.3, 16.7 and 25%. Production of sclerotia by S. rolfsii was diminished by B, but stimulated by SB. Penicillium purpurogenum, P. simplicissimum and Aspergillus niger obtained from B behaved as antagonistic against both pathogens, showing antibiosis, competition and hyperparasitism in dual confrontations with them. Broth and SB at 10 and 50% dilutions were sprayed on chard (Beta vulgaris), tomato (Solanum lycopersicum), pepper (Capsicum annuum) and eggplant (Solanum melongena) seedlings cultivated in pathogen-colonized soil. Damping of incidence in the B treatment at 50% dilution was markedly lower than that in SB. It is concluded that B antifungal activity depends on its dilution and mycota. Broth sprays should be considered as a tool to control damping of in low-environment-impact crop production. Further studies are needed for a complete understanding of B chemical and microbiological components, as well as their changes during fermentation.

MC, Rivera; ER, Wright; MC, Fabrizio; G, Freixá; R, Cabalini; SE, Lopez.

190

Control del mal de los almácigos causado por Rhizoctonia solani y Sclerotium rolfsii con caldos de cebolla / Control of seedling damping off caused by Rhizoctonia solani and Sclerotium rolfsii using onion broths  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish El mal de los almácigos causa muerte de plántulas. Los controles cultural y biológico constituyen las únicas herramientas orgánicas para su manejo. Acerca de la eficiencia de preparaciones vegetales, sólo se encuentra información de divulgación. Este trabajo evalúa el efecto de caldos fermentados de [...] cebolla sobre el crecimiento de Rhizoctonia solani y Sclerotium rolfsii y la incidencia de la enfermedad. Se obtuvieron caldo (B) y caldo esterilizado (SB), respectivamente, mediante hervido de trozos de cebollas y fermentación a temperatura ambiente, con o sin esterilización posterior. Se cultivaron los patógenos en APG suplementado con B y SB diluidos 1,7; 3,3; 8,3; 16,7 y 25%. Su crecimiento decreció con B al 8,3, 16,7 y 25%. La producción de esclerocios por S. rolfsii disminuyó con B, pero aumentó con SB. Penicillium purpurogenum, P. simplicissimum y Aspergillus niger aislados de B evidenciaron antibiosis, competencia e hiperparasitismo respecto de ambos patógenos. B y SB diluidos 10 y 50% fueron aplicados en almácigos de acelga (Beta vulgaris), tomate (Solanum lycopersicum), pimiento (Capsicum annuum) y berenjena (Solanum melongena) infestados. La pérdida de plántulas fue menor en el tratamiento con B al 50%, en relación al tratamiento con SB. Se concluye que la actividad antifúngica de B depende de su dilución y de su micota. La utilización de caldos de cebolla debería ser contemplada como alternativa para el manejo fitosanitario de bajo impacto ambiental. Se requiere continuar los estudios para completar el conocimiento acerca de los componentes químicos y microbiológicos de los caldos, y sus posibles cambios durante la fermentación. Abstract in english Damping off is a frequent disease that kills seedlings. Cultural and biological controls are the only tools in organic crops to manage this disease, and only empirical information is available on the eficiency of plant preparations. This work evaluates the effects of fermented onion decoctions on th [...] e growth of Rhizoctonia solani and Sclerotium rolfsii and disease incidence. Broth (B) and sterilized broth (SB) were respectively obtained by boiling chopped yellow onions in water, and incubating for 14 days at room temperature, with or without subsequent sterilization. The pathogens were grown on potato dextrose agar supplemented with B and SB, diluted at 1.7, 3.3, 8.3, 16.7 and 25% (v/v). Their growth was reduced by B at 8.3, 16.7 and 25%. Production of sclerotia by S. rolfsii was diminished by B, but stimulated by SB. Penicillium purpurogenum, P. simplicissimum and Aspergillus niger obtained from B behaved as antagonistic against both pathogens, showing antibiosis, competition and hyperparasitism in dual confrontations with them. Broth and SB at 10 and 50% dilutions were sprayed on chard (Beta vulgaris), tomato (Solanum lycopersicum), pepper (Capsicum annuum) and eggplant (Solanum melongena) seedlings cultivated in pathogen-colonized soil. Damping of incidence in the B treatment at 50% dilution was markedly lower than that in SB. It is concluded that B antifungal activity depends on its dilution and mycota. Broth sprays should be considered as a tool to control damping of in low-environment-impact crop production. Further studies are needed for a complete understanding of B chemical and microbiological components, as well as their changes during fermentation.

MC, Rivera; ER, Wright; MC, Fabrizio; G, Freixá; R, Cabalini; SE, Lopez.

2013-12-01

191

Respuesta al glifosato de un aislamiento de Rhizoctonia solani agente causal del anublo de la vaina del arroz, y de cuatro aislamientos de Trichoderma, bajo condiciones in vitro In vitro response of one isolate of Rhizoctonia solani, the pathogen of the rice sheath blight and four isolates of Trichoderma to glyphosate  

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El añublo de la vaina del arroz (Orysa saliva L.), cuyo agente causal es Rhizoctonia solani Kuhn, es una de las enfermedades más importantes en el cultivo del arroz en Colombia. En los cultivos de arroz con frecuencia se aplica glifosato ((ácido N-(fosfonometil) glicina) para controlar las malezas, particularmente el arroz rojo (O. saliva), antes de la siembra del arroz. Observaciones de campo anteriores parecían indicar relación entre el uso intensivo del glifosato y el incremento en la...

Vargas de Álvarez Amparo; Fuentes Cilia L.; Torres Torres Enrique

2002-01-01

192

Efeito da solarização do solo, seguida pela aplicação de Trichoderma spp: ou de fungicidas, sobre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4 Effect of soil solarization, followed or not by the application of Trichoderma spp: or fungicides for the control of Pythium aphanidermatum and Rhizoctonia solani AG-4  

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O presente trabalho foi realizado com o objetivo de estudar alternativas para a desinfestação de solos, especialmente considerando a retirada do brometo de metila do mercado. Avaliou-se o efeito da solarização do solo, seguida ou não pela aplicação de isolados de Trichoderma spp. ou de fungicidas, sobre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4, responsáveis por tombamento e podridão de raízes em várias culturas. Dois experimentos foram realizados em Piracic...

Flávia Rodrigues Alves Patrício; Hiroshi Kimati; João Tessarioli Neto; Ademir Petenatti; Benedito De Camargo Barros

2007-01-01

193

Microbial L-phenylalanine ammonia-lyase. Purification, subunit structure and kinetic properties of the enzyme from Rhizoctonia solani.  

Science.gov (United States)

1. Phenylalanine ammonia-lyase (EC 4.3.1.5) was purified to homogeneity from the acetone-dried powders of the mycelial felts of the plant pathogenic fungus Rhizoctonia solani. 2. A useful modification in protamine sulphate treatment to get substantial purification of the enzyme in a single-step is described. 3. The purified enzyme shows bisubstrate activity towards L-phenylalanine and L-tyrosine. 4. It is sensitive to carbonyl reagents and the inhibition is not reversed by gel filtration. 5. The molecular weight of the enzyme as determined by Sephadex G-200 chromatography and sucrose-density-gradient centrifugation is around 330000. 6. The enzyme is made up of two pairs of unidentical subunits, with a molecular weight of 70000 (alpha) and 90000 (beta) respectively. 7. Studies on initial velocity versus substrate concentration have shown significant deviations from Michaelis-Menten kinetics. 8. The double-reciprocal plots are biphasic (concave downwards) and Hofstee plots show a curvilinear pattern. 9. The apparent Km value increases from 0.18 mM to as high as 5.0 mM with the increase in the concentration of the substrate and during this process the Vmax, increases by 2-2.5-fold. 10. The value of Hill coefficient is 0.5. 11. Steady-state rates of phenylalanine ammonia-lyase reaction in the presence of inhibitors like D-phenylalanine, cinnamic, p-coumaric, caffeic, dihydrocaffeic and phenylpyruvic acid have shown that only one molecule of each type of inhibitor binds to a molecule of the enzyme. These observations suggest the involvement of negative homotropic interactions in phenylalanine ammonia-lyase. 12. The enzyme could not be desensitized by treatment with HgCl2, p-chloromercuribenzoic acid or by repeated freezing and thawing. PMID:1191266

Kalghatgi, K K; Subba Rao, P V

1975-07-01

194

Transcriptome analysis of the phytopathogenic fungus Rhizoctonia solani AG1-IB 7/3/14 applying high-throughput sequencing of expressed sequence tags (ESTs).  

Science.gov (United States)

Rhizoctonia solani is a soil-borne plant pathogenic fungus of the phylum Basidiomycota. It affects a wide range of agriculturally important crops and hence is responsible for economically relevant crop losses. Transcriptome analysis of the bottom rot pathogen R. solani AG1-1B (isolate 7/3/14) by applying high-throughput sequencing and bioinformatics methods addressing Expressed Sequence Tag (EST) data interpretation provided new insights in expressed genes of this fungus. Two normalized cDNA libraries representing different cultivation conditions of the fungus were sequenced on the 454 FLX (Roche) system. Subsequent to cDNA sequence assembly and quality control, ESTs were analysed applying advanced bioinformatics methods. More than 14?000 transcript isoforms originating from approximately 10?000 predictable R. solani AG1-IB 7/3/14 genes are represented in each dataset. Comparative analyses revealed several differentially expressed genes depending on the growth conditions applied. Determinants with predicted functions in recognition processes between the fungus and the host plant were identified. Moreover, many R. solani AG1-IB ESTs were predicted to encode putative cellulose, pectin, and lignin degrading enzymes. Furthermore, genes playing a possible role in mitogen-activated protein (MAP) kinase cascades, 4-aminobutyric acid (GABA) metabolism, melanin synthesis, plant defence antagonism, phytotoxin, and mycotoxin synthesis were detected. PMID:25209639

Wibberg, Daniel; Jelonek, Lukas; Rupp, Oliver; Kröber, Magdalena; Goesmann, Alexander; Grosch, Rita; Pühler, Alfred; Schlüter, Andreas

2014-01-01

195

Relación entre la estructura de la comunidad bacteriana y la supresión al ahogamiento causado por Rhizoctonia solani en sustratos para plántulas de tomate  

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Full Text Available En este trabajo el objetivo fue estudiar la relación entre la supresión del ahogamiento causado por Rhizoctonia solani y la estructura de la comunidad bacteriana en sustratos orgánicos (con base en vermicomposta y composta, para el crecimiento de plántulas de tomate. Dicha estructura comunitaria se determinó mediante T-RFLP (Terminal Restriction Fragment Length Polymorphisms del gen ARNr 16S, con la enzima Hin6I. Análisis de componentes principales (PCA a partir de las abundancias relativas de los T-RFs (Fragmentos de Restricción Terminales predominantes, mostraron que los sustratos con tendencia supresiva al patógeno poseen comunidades bacterianas similares, indicando la existencia de una relación entre la estructura de la comunidad y la supresividad. Los T-RFs predominantes se relacionaron con secuencias obtenidas de una librería genómica del gen ribosomal ARNr 16S de un sustrato con tendencia supresiva. Dicho análisis de PCA reveló que entre los TRFs que contribuyen a la diferenciación de los sustratos con tendencias supresivas, se encuentran tres (64, 205 y 211 que corresponden a secuencias 16S de los siguientes géneros: Burkholderia, Duganella, Telluria, Janthinobacterium, Pseudmomonas, Stenotrophomonas y Xanthomonas. Tales géneros presentan especies con capacidad biocontroladora específica sobre el patógeno, por lo que estos resultados sugieren que los T-RFs (Hin6I 64, 205, 211 y otros, podrían ser utilizados como indicadores a priori de la capacidad supresiva de un sustrato al ahogamiento causado por Rhizoctonia solani.

O. Robledo

2010-01-01

196

Efectividad Biológica de TCMTB para el Control de la Costra Negra Rhizoctonia solani Kühn de la Papa Solanum Tuberosum L., en la Región de León, Guanajuato, México Efectividad Biológica de TCMTB para el Control de la Costra Negra Rhizoctonia solani Kühn de la Papa Solanum Tuberosum L., en la Región de León, Guanajuato, México  

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Full Text Available During the 1988 summer-fall growing cycle in the Mexican region of Leon, Guanajuato the fungicide 2-(Thiocyanomethylthio benzothiazole (TCMTB was evaluated applying it at the rate of 6, 8 and 10 liters per hectare for the control of soil borne Black Scurf R. solani. A randomized block design with four reps was used. An evaluation was made of the following: emerged stems, phytotoxical damage, percentage of damaged shoots and stems by R. solani, yield and tuber quality; finally, percentage of R. solani damaged tuber and percentage of tubers with over 5% of damage inflicted by R. solani. It was found that no phytotoxic effect of fungicide to the potato crop was observed; that any of the fungicides comprising treatments protected the plant shoots; that no statistic differences were found among treatments pertaining tuber yield; finally the rates 8.0 and 10.0 l/ha of TCMTB and 5.0 kg/ha of pencycuron produced 27, 20 y 25 percentage of tubers with over 5% of damage inflicted by R. solani, propitiated the highest potato quality when reducing R. solani damage to tubers. En la región de León, Guanajuato, México durante el ciclo verano-otoño 1998, se evaluó el fungicida 2-(Thiocyanomethylthio benzothiazole (TCMTB en dosis de 6, 8 y 10 litros por hectárea para el control del hongo del suelo Rhizoctonia solani Kühn. Se usó un diseño de bloques al azar, con cuatro repeticiones. Se evaluó el número de tallos emergidos, el efecto fitotóxico, los porcentajes de brotes y tallos dañados por R. solani, el rendimiento y calidad del tubérculo; finalmente, el porcentaje de daño de R. solani al tubérculo y el porcentaje de tubérculos con más del 5% de daño por R. solani. Se encontró que no hubo efecto fitotóxico del fungicida al cultivo de papa; que cualquiera de los tratamientos que contenían fungicidas protegieron los brotes de las plantas; que no hubo diferencias estadísticas entre tratamientos con respecto al rendimiento de tubérculos; finalmente, las dosis de 8.0 y 10.0 l/ha de TCMTB y 5.0 kg/ha de pencycuron presentaron 27, 20 y 25 % de tubérculos con más del 5% de daño por el patógeno, respectivamente, propiciando la mayor calidad de papa, al reducir el daño de R. solani a los tubérculos.

Fernando Javier Cantú Galindo

2012-02-01

197

Rice oxalate oxidase gene driven by green tissue-specific promoter increases tolerance to sheath blight pathogen (Rhizoctonia solani) in transgenic rice.  

Science.gov (United States)

Rice sheath blight, caused by the necrotrophic fungus Rhizoctonia solani, is one of the most devastating and intractable diseases of rice, leading to a significant reduction in rice productivity worldwide. In this article, in order to examine sheath blight resistance, we report the generation of transgenic rice lines overexpressing the rice oxalate oxidase 4 (Osoxo4) gene in a green tissue-specific manner which breaks down oxalic acid (OA), the pathogenesis factor secreted by R.?solani. Transgenic plants showed higher enzyme activity of oxalate oxidase (OxO) than nontransgenic control plants, which was visualized by histochemical assays and sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Transgenic rice leaves were more tolerant than control rice leaves to exogenous OA. Transgenic plants showed a higher level of expression of other defence-related genes in response to pathogen infection. More importantly, transgenic plants exhibited significantly enhanced durable resistance to R.?solani. The overexpression of Osoxo4 in rice did not show any detrimental phenotypic or agronomic effect. Our findings indicate that rice OxO can be utilized effectively in plant genetic manipulation for sheath blight resistance, and possibly for resistance to other diseases caused by necrotrophic fungi, especially those that secrete OA. This is the first report of the expression of defence genes in rice in a green tissue-specific manner for sheath blight resistance. PMID:23809026

Molla, Kutubuddin A; Karmakar, Subhasis; Chanda, Palas K; Ghosh, Satabdi; Sarkar, Sailendra N; Datta, Swapan K; Datta, Karabi

2013-12-01

198

Evaluación de la actividad quitinasa en procesos de control biológico de rhizoctonia solani y fusarium oxysporum f. sp. lycopersici en tomate, mediante fitoinvigorización de semillas en presencia de trichoderma koningii Evaluation of chitinase activity in biological control process of rhizoctonia solani y fusarium oxysporum f. sp. lycopersici in tomate, by using seed priming in the presence of trichoderma koningii  

Digital Repository Infrastructure Vision for European Research (DRIVER)

El propósito del presente trabajo fue el de establecer el posible papel de las quitinasas en un modelo de control, utilizando pregerminación controlada de semillas en presencia de Trichoderma koningii. Este método mostró ser eficiente para el control de Rhizoctonia solani y de Fusarium oxysporum en tomate. Al analizar los extractos y exudados de semillas y los extractos de suel...

Cotes A. M.; Clavijo A.

1998-01-01

199

Associação de Rhizoctonia solani Grupo de Anastomose 4 (AG-4 HGI e HGIII) à espécies de plantas invasoras de área de cultivo de batata / Rhizoctonia solani anastomosis group 4 (AG-4 HGI and HGIII) associated with weed species from a potato cropping area  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os grupos 3 e 4 de anastomose (AG-3 e AG-4) do fungo Rhizoctonia solani são importantes grupos associados à batata no mundo. No Brasil, o AG-3 é relatado afetando principalmente batata e fumo. Já o AG-4 causa perdas consideráveis em culturas de importância econômica, como a soja, o feijão e o amendo [...] im, podendo ocorrer também em hortaliças como o espinafre, o pimentão, o brócolis, o tomate, a batata e frutíferas como o melão. Recentemente foi constatada, em Brasília-DF, a associação de R. solani a plantas invasoras em áreas de cultivo de batata. Entretanto, não há informação a respeito da etiologia do patógeno bem como do papel de espécies invasoras como outras hospedeiras no ciclo do patógeno. Objetivou-se com esse estudo caracterizar isolados de R. solani obtidos de batata e de outras três espécies de plantas invasoras associadas a áreas de cultivo da cultura: juá-de-capote [Nicandra physaloides (L.) Pers., Solanaceae], beldroega (Portulaca oleracea L., Portulacaceae), e caruru (Amaranthus deflexus L., Amaranthaceae). Foi confirmada a hipótese de que os isolados obtidos de R. solani de beldroega, caruru e juá-de-capote pertencem ao grupo 4 de anastomose e são patogênicos à batata, exceto o isolado de beldroega. Estes isolados apresentaram patogenicidade cruzada às três espécies e também patogênicos à maria-pretinha (Solanum americanum Mill.), uma outra espécie de Solanaceae invasora. A classificação dos isolados no grupo AG-4 HGI ou no grupo AG-4 HGIII (isolado de caruru) foi confirmada através de características culturais e moleculares (seqüenciamento da região ITS-5.8S do rDNA). Os resultados deste trabalho trazem implicações importantes para o manejo das podridões radiculares de Rhizoctonia em batata. Abstract in english The anastomosis groups 3 and 4 (AG-3 and AG-4) of the fungus Rhizoctonia solani are important groups associated with potatoes worldwide. In Brazil, the AG-3 is reported affecting mainly potatoes and tobacco. The AG-4 cause considerable losses in crops of economic importance, such as soybean, beans a [...] nd peanuts and may also occur in vegetables such as spinach, pepper, broccoli, tomatoes, potatoes and fruit such as melons. The association of R. solani with invasive plants was recently established in potato production areas from Brasília, DF. However, there is no information about the etiology of the pathogen as well as the role of invasive species as alternative hosts in the life cycle of the pathogen. The objective of this study was to characterize isolates of R. solani obtained from potatoes and three other invasive plant species associated with areas of potato production: Shoo-fly plant [Nicandra physaloides (L.) Pers., Solanaceae], pigweed (Portulaca oleracea L., Portulacaceae), and low-amaranth (Amaranthus deflexus L., Amaranthaceae). It was confirmed the hypothesis that the R. solani isolates obtained from pigweed, low-amaranth and Shoo-fly plant belong to the anastomosis group 4 and, except for the isolate from pigweed, are pathogenic to potatoes. These isolates were cross pathogencic to all the three weed species tested and also to American nightshade (Solanum americanum Mill.), another Solanaceae invasive of potato fields. The placement of the isolates in the group AG-4 HGI or in the group AG-4 HGIII (isolate from caruru) was confirmed by cultural and molecular characteristics (sequencing of the ITS-5.8S region of rDNA). The results of this study provide important implications for the management of the Rhizoctonia root rot in potatoes.

Fátima Aparecida da, Silva-Barreto; Wagner Vicente, Pereira; Maisa Boff, Ciampi; Marcos Paz Saraiva, Câmara; Paulo Cezar, Ceresini.

200

Associação de Rhizoctonia solani Grupo de Anastomose 4 (AG-4 HGI e HGIII) à espécies de plantas invasoras de área de cultivo de batata / Rhizoctonia solani anastomosis group 4 (AG-4 HGI and HGIII) associated with weed species from a potato cropping area  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os grupos 3 e 4 de anastomose (AG-3 e AG-4) do fungo Rhizoctonia solani são importantes grupos associados à batata no mundo. No Brasil, o AG-3 é relatado afetando principalmente batata e fumo. Já o AG-4 causa perdas consideráveis em culturas de importância econômica, como a soja, o feijão e o amendo [...] im, podendo ocorrer também em hortaliças como o espinafre, o pimentão, o brócolis, o tomate, a batata e frutíferas como o melão. Recentemente foi constatada, em Brasília-DF, a associação de R. solani a plantas invasoras em áreas de cultivo de batata. Entretanto, não há informação a respeito da etiologia do patógeno bem como do papel de espécies invasoras como outras hospedeiras no ciclo do patógeno. Objetivou-se com esse estudo caracterizar isolados de R. solani obtidos de batata e de outras três espécies de plantas invasoras associadas a áreas de cultivo da cultura: juá-de-capote [Nicandra physaloides (L.) Pers., Solanaceae], beldroega (Portulaca oleracea L., Portulacaceae), e caruru (Amaranthus deflexus L., Amaranthaceae). Foi confirmada a hipótese de que os isolados obtidos de R. solani de beldroega, caruru e juá-de-capote pertencem ao grupo 4 de anastomose e são patogênicos à batata, exceto o isolado de beldroega. Estes isolados apresentaram patogenicidade cruzada às três espécies e também patogênicos à maria-pretinha (Solanum americanum Mill.), uma outra espécie de Solanaceae invasora. A classificação dos isolados no grupo AG-4 HGI ou no grupo AG-4 HGIII (isolado de caruru) foi confirmada através de características culturais e moleculares (seqüenciamento da região ITS-5.8S do rDNA). Os resultados deste trabalho trazem implicações importantes para o manejo das podridões radiculares de Rhizoctonia em batata. Abstract in english The anastomosis groups 3 and 4 (AG-3 and AG-4) of the fungus Rhizoctonia solani are important groups associated with potatoes worldwide. In Brazil, the AG-3 is reported affecting mainly potatoes and tobacco. The AG-4 cause considerable losses in crops of economic importance, such as soybean, beans a [...] nd peanuts and may also occur in vegetables such as spinach, pepper, broccoli, tomatoes, potatoes and fruit such as melons. The association of R. solani with invasive plants was recently established in potato production areas from Brasília, DF. However, there is no information about the etiology of the pathogen as well as the role of invasive species as alternative hosts in the life cycle of the pathogen. The objective of this study was to characterize isolates of R. solani obtained from potatoes and three other invasive plant species associated with areas of potato production: Shoo-fly plant [Nicandra physaloides (L.) Pers., Solanaceae], pigweed (Portulaca oleracea L., Portulacaceae), and low-amaranth (Amaranthus deflexus L., Amaranthaceae). It was confirmed the hypothesis that the R. solani isolates obtained from pigweed, low-amaranth and Shoo-fly plant belong to the anastomosis group 4 and, except for the isolate from pigweed, are pathogenic to potatoes. These isolates were cross pathogencic to all the three weed species tested and also to American nightshade (Solanum americanum Mill.), another Solanaceae invasive of potato fields. The placement of the isolates in the group AG-4 HGI or in the group AG-4 HGIII (isolate from caruru) was confirmed by cultural and molecular characteristics (sequencing of the ITS-5.8S region of rDNA). The results of this study provide important implications for the management of the Rhizoctonia root rot in potatoes.

Fátima Aparecida da, Silva-Barreto; Wagner Vicente, Pereira; Maisa Boff, Ciampi; Marcos Paz Saraiva, Câmara; Paulo Cezar, Ceresini.

2010-06-01

 
 
 
 
201

Bioconversion of wheat straw and wheat straw components into single-cell protein. [Spicaria fusispora, Cochliobolus specifer, Myrothecium verrucaria, Rhizoctonia solani, and Gliocladium sp  

Energy Technology Data Exchange (ETDEWEB)

Several fungi (Aspergillus niger, A. terreus, Cochliobolus specifer, Myrothecium verrucaria, Rhizoctonia solani, Spicaria fusispora, Penicillium sp., and Gliocladium sp.) were isolated from decomposing wheat straw and tested for their ability to utilize whole straw and its components, holocellulose (hemicellulose and cellulose) and cellulose, for the production of single-cell protein (SCP). C. specifer was the most efficient fungus for protein synthesis with the 3 substrates. Using KNO/sub 3/ as N source in mixtures of .04 g N/g substrate (0.04% wt./vol.) at pH 4.5, it was found that incubation periods of 3, 4, and 5 days were optimal for protein production on cellulose and holocellulose fractions, and whole straw, respectively. Whole native straw was the most recalcitrant to bioconversion into SCP; however, protein production was almost doubled when the lignin component was removed using a mixture of NaClO/sub 2/ and HOAc.

Chahal, D.S.; Moo-Young, M.; Dhillon, G.S.

1979-01-01

202

Surface motility in Pseudomonas sp DSS73 is required for efficient biological containment of the root-pathogenic microfungi Rhizoctonia solani and Pythium ultimum  

DEFF Research Database (Denmark)

Pseudomonas sp. DSS73 was isolated from the rhizoplane of sugar beet seedlings. This strain exhibits antagonism towards the root-pathogenic microfungi Pythium ultimum and Rhizoctonia solani. Production of the cyclic lipopeptide amphisin in combination with expression of flagella enables the growing bacterial culture to move readily over the surface of laboratory media. Amphisin is a new member of a group of dual-functioning compounds such as tensin, viscosin and viscosinamid that display both biosurfactant and antifungal properties. The ability of DSS73 to efficiently contain root-pathogenic microfungi is shown to arise from amphisin-dependent surface translocation and growth by which the bacterium can lay siege to the fungi. The synergistic effects of surface motility and synthesis of a battery of antifungal compounds efficiently contain and terminate growth of the microfungi.

Andersen, Jens Bo; Koch, Birgit

2003-01-01

203

Mating type-correlated molecular markers and demonstration of heterokaryosis in the phytopathogenic fungus Thanatephorus cucumeris (Rhizoctonia solani) AG 1-IC by AFLP DNA fingerprinting analysis.  

Science.gov (United States)

The destructive soil-borne plant pathogenic basidiomycetous fungus Thanatephorus cucumeris (Frank) Donk [anamorph: Rhizoctonia solani Kühn] is not a homogeneous species, but is composed of at least twelve anastomosis groups (AG), which seem to be genetically isolated. The genetics of several T. cucumeris anastomosis groups has been studied by analysis of heterokaryotic tuft formation in the area of contact between homokaryotic single-spore isolates, revealing that AG 1 is heterokaryotic and bipolar. To prove that tuft formation is due to heterokaryosis, AFLP DNA fingerprinting has been applied to a heterokaryotic T. cucumeris AG 1-IC isolate, its homokaryotic single spore-derived progeny, and newly formed heterokaryons. By means of AFLP markers, it is demonstrated that fluffy tufts formed upon pairing of homokaryons from different mating types are newly formed heterokaryons. Mating type-correlated markers have also been found, which will be useful for future studies of the genetics of this fungal species complex. PMID:9987848

Julián, M C; Acero, J; Salazar, O; Keijer, J; Rubio, V

1999-01-01

204

Determination of the Anastomosis Grouping and Virulence of Rhizoctonia solani Kuhn Isolates Associated with Bean Plants Grown in Samsun/Turkey  

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Full Text Available Anastomosis groupings and virulence of 229 Rhizoctonia solani isolates, obtained from bean plants and soils in Samsun province, were determined. About 59 % of the isolates belonged to anastomosis group AG 4, 31 % to AG 2-2 and the remaining 10 % to AG 5. All the isolates selected for the pathogenicity test were found to be virulent at varying degrees to eight plants from different families. Isolate HAF 1-3 belonging to AG 4 were found to be the most virulent isolate. Sugarbeet was the most susceptible plant species while corn and leek seemed to be rather resistant. The virulence of the isolates on different bean cultivars varied. AG 4 and AG 2-2 group isolates caused severe symptoms of root rot on all cultivars. AG 5 isolate was highly to moderately virulent regarding the susceptibility of the bean cultivars. Horoz was found to be the most susceptible bean cultivar.

G. H. Karaca

2002-01-01

205

Potencial antifúngico de cepas de Bacillusspp. y extracto de Larrea tridentatacontra Rhizoctonia solanien el cultivo de la papa (Solanum tuberosum L.) / Antifungal potential of Bacillus spp. strains and Larrea tridentata extract against Rhizoctonia solani on potato (Solanum tuberosum L.) crop  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish El cultivo de papa en México es el que más funguicidas requiere para prevenir y controlar diversas enfermedades, estimándose que en este cultivo se aplican el 21,3% del total de los funguicidas disponibles. Los pesticidas sintéticos se destinan principalmente para combatir los hongos Phytophthora in [...] festans y Rhizoctonia solani. Esto trae como consecuencia severos daños a la salud y a los ecosistemas; es por eso que existe la necesidad de encontrar nuevas opciones para el manejo sustentable de los patógenos que atacan a este cultivo. Se realizaron investigaciones en condiciones de laboratorio, invernadero y campo con los siguientes objetivos (1) analizar el efecto antifúngico de tres cepas de bacterias del género Bacillus (B3, B9 y B15) contra R. solani, así como su efecto promotor del crecimiento en plantas de papa, (2) determinar el efecto de un extracto resinoso obtenido de hojas de Larrea tridentata contra el hongo R. solani, y (3) establecer si existe un efecto sinérgico al mezclar las cepas de Bacillus con el extracto de L. tridentata. Los resultados indicaron que las cepas bacterianas tuvieron una clara actividad antifúngica, al igual que el extracto de L. tridentata. Las cepas de Bacillus sobresalieron además por su efecto estimulador del crecimiento de las plantas y del rendimiento de papa, así como por el efecto sinérgico al mezclar las bacterias con el extracto de Larrea; un efecto potenciador similar se observó al aplicar la mezcla de las cepas. Los resultados obtenidos con las cepas de Bacillus, así como su mezcla con el extracto de L. tridentata son alentadores. Los mismos sugieren que podrían ser utilizados para apoyar programas de control biológico contra R. solani. Sin embargo, es necesario continuar con más trabajos in vivo para validar estos resultados. Abstract in english Potato crop requires more fungicides than any other crop in Mexico to prevent and control several diseases. More than 21,3% of the total available fungicides are required for cropping potato. High quantities of synthetic pesticides are intended to control Phytophthora infestans and Rhizoctonia solan [...] i fungi. As a result, this produces severe health problems and ecosystem disturbances. There is then an urgent need for finding new options for sustainable management of potato crop diseases. Several experiments were conducted under laboratory, greenhouse, and field conditions, to: (1) analyze the antifungal effect of bacteria strains of the genus Bacillus, and their effect on potato plant growth; (2) determine the effect of a resinous extract from Larrea tridentata leaves against the fungus R. solani, and (3) establish if there is a synergic effect when Bacillus spp. are mixed with L. tridentata extract. Results indicate an antifungal effect of bacterial strains and Larrea extract. Bacillus strains also stimulated plant growth and yield increase. A synergic effect was detected when Bacillus spp. were mixed with Larrea extract; a similar outcome occurred with the mixture of B3, B9 and B15 strains. Results obtained with Bacillus and Larrea, as well as with their mixture are encouraging since they could be used as an organic option for biological control programs against the fungus R. solani. However, more in vivo research is necessary to validate these results.

FD, Hernández-Castillo; RH, Lira-Saldivar; L, Cruz-Chávez; G, Gallegos-Morales; Me, Galindo-Cepeda; E, Padrón-Corral; M, Hernández-Suárez.

206

Eficiência de diferentes moléculas na redução dos sintomas da queima das bainhas em arroz e no crescimento de Rhizoctonia solani in vitro / Efficiency of different molecules on the reduction of sheath blight symptoms in rice and on Rhizoctonia solani growth in vitro  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este estudo verificou a eficiência da aplicação de diferentes moléculas em reduzir o comprimento relativo da lesão (CRL) da queima das bainhas em arroz. Plantas dos cultivares BR-Irga 409 e Labelle foram cultivadas em solução nutritiva e inoculadas com Rhizoctonia solani, no estádio de máximo perfil [...] hamento. Às 24 horas antes da inoculação, as bainhas das plantas foram pulverizadas com soluções de silicato de potássio (SP), silicato de potássio + fósforo (SP+F), Acibenzolar-S-Metil (ASM), fungicida Carbendazim, quitosana desacetilada (QD), etileno (ET) e fosfito de potássio (FP). Plantas cujas bainhas foram pulverizadas com água destilada serviram como testemunhas. O efeito das moléculas contidas nesses produtos no crescimento micelial de R. solani foi testado in vitro. Para BR-Irga 409, o CRL foi menor com a aplicação do FP, em relação aos demais tratamentos, exceto o Carbendazim. A aplicação do Carbendazim reduziu em 86,1% o CRL, em relação à testemunha. O CRL foi significativamente menor no cultivar BR-Irga 409 do que no 'Labelle', com aplicação do FP. O crescimento micelial de R. solani foi reduzido apenas pelo FP e Carbendazim, em comparação com os demais tratamentos. Não houve diferença significativa entre os tratamentos testemunha, SP e SP+F para a concentração de Si nas bainhas das plantas dos dois cultivares. Abstract in english This study aimed to test the efficiency of different molecules on the reduction of the relative lesion extension (RLE) of sheath blight in rice. Plants of cultivars BR-Irga 409 and Labelle were grown in nutrient solution and inoculated with Rhizoctonia solani at the maximum tillering stage. At 24 ho [...] urs before inoculation, sheaths of plants were sprayed with solutions of potassium silicate (PS), potassium silicate + phosphorus (PS+P), Acibenzolar-S-Methyl (ASM), Carbendazim fungicide, deacetylated chitosan (DC), ethylene (ET) and potassium phosphite (PP). Sheaths from plants sprayed with water served as the control treatment. The effect of these products on R. solani mycelia growth was also studied in vitro. For BR-Irga 409, the RLE was lower with the application of PP compared with the other treatments, except the Carbendazim. The application of Carbendazim reduced in 86.1% the RLE in comparison with the control. The RLE was lower for BR-Irga 409 than for Labell with the application of PP. Mycelia growth of R. solani was inhibited only by PP and Carbendazim in comparison with the other treatments. There was no significant difference among the treatments control, PS, and PS+P for silicon concentration on sheaths of plants of the two cultivars.

Daniel Augusto, Schurt; Fabrício Ávila, Rodrigues; Naiara Fernandes Abreu, Souza; Ricardo Dutra, Reis.

2013-04-01

207

Eficiência de diferentes moléculas na redução dos sintomas da queima das bainhas em arroz e no crescimento de Rhizoctonia solani in vitro Efficiency of different molecules on the reduction of sheath blight symptoms in rice and on Rhizoctonia solani growth in vitro  

Directory of Open Access Journals (Sweden)

Full Text Available Este estudo verificou a eficiência da aplicação de diferentes moléculas em reduzir o comprimento relativo da lesão (CRL da queima das bainhas em arroz. Plantas dos cultivares BR-Irga 409 e Labelle foram cultivadas em solução nutritiva e inoculadas com Rhizoctonia solani, no estádio de máximo perfilhamento. Às 24 horas antes da inoculação, as bainhas das plantas foram pulverizadas com soluções de silicato de potássio (SP, silicato de potássio + fósforo (SP+F, Acibenzolar-S-Metil (ASM, fungicida Carbendazim, quitosana desacetilada (QD, etileno (ET e fosfito de potássio (FP. Plantas cujas bainhas foram pulverizadas com água destilada serviram como testemunhas. O efeito das moléculas contidas nesses produtos no crescimento micelial de R. solani foi testado in vitro. Para BR-Irga 409, o CRL foi menor com a aplicação do FP, em relação aos demais tratamentos, exceto o Carbendazim. A aplicação do Carbendazim reduziu em 86,1% o CRL, em relação à testemunha. O CRL foi significativamente menor no cultivar BR-Irga 409 do que no 'Labelle', com aplicação do FP. O crescimento micelial de R. solani foi reduzido apenas pelo FP e Carbendazim, em comparação com os demais tratamentos. Não houve diferença significativa entre os tratamentos testemunha, SP e SP+F para a concentração de Si nas bainhas das plantas dos dois cultivares.This study aimed to test the efficiency of different molecules on the reduction of the relative lesion extension (RLE of sheath blight in rice. Plants of cultivars BR-Irga 409 and Labelle were grown in nutrient solution and inoculated with Rhizoctonia solani at the maximum tillering stage. At 24 hours before inoculation, sheaths of plants were sprayed with solutions of potassium silicate (PS, potassium silicate + phosphorus (PS+P, Acibenzolar-S-Methyl (ASM, Carbendazim fungicide, deacetylated chitosan (DC, ethylene (ET and potassium phosphite (PP. Sheaths from plants sprayed with water served as the control treatment. The effect of these products on R. solani mycelia growth was also studied in vitro. For BR-Irga 409, the RLE was lower with the application of PP compared with the other treatments, except the Carbendazim. The application of Carbendazim reduced in 86.1% the RLE in comparison with the control. The RLE was lower for BR-Irga 409 than for Labell with the application of PP. Mycelia growth of R. solani was inhibited only by PP and Carbendazim in comparison with the other treatments. There was no significant difference among the treatments control, PS, and PS+P for silicon concentration on sheaths of plants of the two cultivars.

Daniel Augusto Schurt

2013-04-01

208

Eficiência de diferentes moléculas na redução dos sintomas da queima das bainhas em arroz e no crescimento de Rhizoctonia solani in vitro / Efficiency of different molecules on the reduction of sheath blight symptoms in rice and on Rhizoctonia solani growth in vitro  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este estudo verificou a eficiência da aplicação de diferentes moléculas em reduzir o comprimento relativo da lesão (CRL) da queima das bainhas em arroz. Plantas dos cultivares BR-Irga 409 e Labelle foram cultivadas em solução nutritiva e inoculadas com Rhizoctonia solani, no estádio de máximo perfil [...] hamento. Às 24 horas antes da inoculação, as bainhas das plantas foram pulverizadas com soluções de silicato de potássio (SP), silicato de potássio + fósforo (SP+F), Acibenzolar-S-Metil (ASM), fungicida Carbendazim, quitosana desacetilada (QD), etileno (ET) e fosfito de potássio (FP). Plantas cujas bainhas foram pulverizadas com água destilada serviram como testemunhas. O efeito das moléculas contidas nesses produtos no crescimento micelial de R. solani foi testado in vitro. Para BR-Irga 409, o CRL foi menor com a aplicação do FP, em relação aos demais tratamentos, exceto o Carbendazim. A aplicação do Carbendazim reduziu em 86,1% o CRL, em relação à testemunha. O CRL foi significativamente menor no cultivar BR-Irga 409 do que no 'Labelle', com aplicação do FP. O crescimento micelial de R. solani foi reduzido apenas pelo FP e Carbendazim, em comparação com os demais tratamentos. Não houve diferença significativa entre os tratamentos testemunha, SP e SP+F para a concentração de Si nas bainhas das plantas dos dois cultivares. Abstract in english This study aimed to test the efficiency of different molecules on the reduction of the relative lesion extension (RLE) of sheath blight in rice. Plants of cultivars BR-Irga 409 and Labelle were grown in nutrient solution and inoculated with Rhizoctonia solani at the maximum tillering stage. At 24 ho [...] urs before inoculation, sheaths of plants were sprayed with solutions of potassium silicate (PS), potassium silicate + phosphorus (PS+P), Acibenzolar-S-Methyl (ASM), Carbendazim fungicide, deacetylated chitosan (DC), ethylene (ET) and potassium phosphite (PP). Sheaths from plants sprayed with water served as the control treatment. The effect of these products on R. solani mycelia growth was also studied in vitro. For BR-Irga 409, the RLE was lower with the application of PP compared with the other treatments, except the Carbendazim. The application of Carbendazim reduced in 86.1% the RLE in comparison with the control. The RLE was lower for BR-Irga 409 than for Labell with the application of PP. Mycelia growth of R. solani was inhibited only by PP and Carbendazim in comparison with the other treatments. There was no significant difference among the treatments control, PS, and PS+P for silicon concentration on sheaths of plants of the two cultivars.

Daniel Augusto, Schurt; Fabrício Ávila, Rodrigues; Naiara Fernandes Abreu, Souza; Ricardo Dutra, Reis.

209

Impact of Gamma Irradiation Stresses II. Control of Sugarbeet Pathogens Rhizoctonia solani Kuhn and Sclerotium rolfsii Sacc.  

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Full Text Available To control the fungal pathogens attacked sugarbeet plant, we subjected R. solani and S. rolfsii to different gamma irradiation doses (0.0, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 and 7.0 kGy for R. solani and 0.0, 0.5, 1.0, 2.0, 3.0 and 4.0 kGy for S. rolfsii. The growth activities of R. solani were completely inhibited at dose 7.0 kGy, while S. rolfsii at 4.0 kGy. The infection percentage was inhibited with gamma irradiation doses increased for both R. solani and S. rolfsii. This was confirmed by the SDS-PAGE for cellular proteins of both R. solani and S. rolfsii, which showed a great variation in protein bands for the same fungus at different gamma irradiation doses. Finally, we can conclude that the gamma irradiation dose to control pathogenic fungi varies with different pathogenic fungi to control the pathogenicity of R. solani, we irradiate it at 7.0 kGy dose while at 4.0 kGy for S. rolfsii.

Tarek A. A. Moussa

2003-01-01

210

In vitro antifungal activities of extracts of fruits and other morphological parts of xanthium strumarium against the plant pathogen, rhizoctonia solani  

International Nuclear Information System (INIS)

In vitro antifungal activity of different plant parts of Xanthium strumarium (Compositae) was investigated against Rhizoctonia solani to seek safe natural alternatives to the harmful synthetic fungicides. The most active plant parts of X. strumarium were seeds, extracted with n-hexane and the leaves, extracted with absolute ethanol. The two treatments resulted in growth inhibition diameters of 45 mm and 47 mm, respectively. The value of MIC lied between 350.0 and 175.0 mg of Xanthium oil/mL. Gas liquid chromatography of the seed oil of X. strumarium revealed the presence of the usual fatty acids, palmitoleic (7.6%), oleic (21.6%) and linoleic (70.4%). The oil was separated into free fatty acids fraction and unsaponifiable matter fraction. The unsaponifiable matter fraction was separated on TLC, out of six separated compounds, two were active against R. solani. The infrared spectra (FTIR) of these two purified compounds pointed to a long chain hydrocarbon back-bone for both, one of them possessing in addition, an alcoholic moiety. (author)

211

Antagonistic Potentials of Rhizosphere-associated Bacterial Isolates Against Soil-borne Diseases of Tomato and Pepper Caused by Sclerotinia sclerotiorum and Rhizoctonia solani  

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Full Text Available By use of selective media, putative antagonist bacterial isolates were isolated from rhizosphere-associated soils from different parts of the Amik plain. Isolates to be tested were chosen in approximate proportion to their abundance on the plates. Selected 113 bacterial isolates were screened for in vitro antagonism towards two important soil-borne root infecting plant pathogens, Sclerotinia sclerotiorum and Rhizoctonia solani by using dual culture test. From this test, significant numbers of bacterial isolates, but not the yeast, were found to produce inhibition zones by inhibiting the hyphal growth of fungal pathogens to a varying degree. On the basis of the result obtained from the preliminary screening test, isolates belonging to Bacillus spp. and Pseudomonas spp. found to be highly efficient against fungal pathogens used in the experiment. Among the inhibitory isolates, bacterial isolates AKB50 and AFP104 significantly suppressed hyphal growth of S. sclerotiorum and R. solani by 75.3 and 83.3%, respectively. This study indicates that selected bacterial strain have potential for controlling of soil-borne disease agents.

Soner Soylu

2005-01-01

212

Distinctively variable sequence-based nuclear DNA markers for multilocus phylogeography of the soybean- and rice-infecting fungal pathogen Rhizoctonia solani AG-1 IA  

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Full Text Available SciELO Brazil | Language: English Abstract in english A series of multilocus sequence-based nuclear DNA markers was developed to infer the phylogeographical history of the Basidiomycetous fungal pathogen Rhizoctonia solani AG-1 IA infecting rice and soybean worldwide. The strategy was based on sequencing of cloned genomic DNA fragments (previously used [...] as RFLP probes) and subsequent screening of fungal isolates to detect single nucleotide polymorphisms (SNPs). Ten primer pairs were designed based on these sequences, which resulted in PCR amplification of 200-320 bp size products and polymorphic sequences in all markers analyzed. By direct sequencing we identified both homokaryon and heterokaryon (i.e. dikaryon) isolates at each marker. Cloning the PCR products effectively estimated the allelic phase from heterokaryotic isolates. Information content varied among markers from 0.5 to 5.9 mutations per 100 bp. Thus, the former RFLP codominant probes were successfully converted into six distinctively variable sequence-based nuclear DNA markers. Rather than discarding low polymorphism loci, the combination of these distinctively variable anonymous nuclear markers would constitute an asset for the unbiased estimate of the phylogeographical parameters such as population sizes and divergent times, providing a more reliable species history that shaped the current population structure of R. solani AG-1 IA.

Maisa B., Ciampi; Liane Rosewich, Gale; Eliana G. de Macedo, Lemos; Paulo C., Ceresini.

213

Biocontrol of Rhizoctonia solani damping-off and promotion of tomato plant growth by endophytic actinomycetes isolated from native plants of Algerian Sahara.  

Science.gov (United States)

Thirty-four endophytic actinomycetes were isolated from the roots of native plants of the Algerian Sahara. Morphological and chemical studies showed that twenty-nine isolates belonged to the Streptomyces genus and five were non-Streptomyces. All isolates were screened for their in vitro antifungal activity against Rhizoctonia solani. The six that had the greatest pathogen inhibitory capacities were subsequently tested for their in vivo biocontrol potential on R. solani damping-off in sterilized and non-sterilized soils, and for their plant-growth promoting activities on tomato seedlings. In both soils, coating tomato seeds with antagonistic isolates significantly reduced (P<0.05) the severity of damping-off of tomato seedlings. Among the isolates tested, the strains CA-2 and AA-2 exhibited the same disease incidence reduction as thioperoxydicarbonic diamide, tetramethylthiram (TMTD) and no significant differences (P<0.05) were observed. Furthermore, they resulted in a significant increase in the seedling fresh weight, the seedling length and the root length of the seed-treated seedlings compared to the control. The taxonomic position based on 16S rDNA sequence analysis and phylogenetic studies indicated that the strains CA-2 and AA-2 were related to Streptomyces mutabilis NBRC 12800(T) (100% of similarity) and Streptomyces cyaneofuscatus JCM 4364(T) (100% of similarity), respectively. PMID:23920229

Goudjal, Yacine; Toumatia, Omrane; Yekkour, Amine; Sabaou, Nasserdine; Mathieu, Florence; Zitouni, Abdelghani

2014-01-20

214

Rhizoctonia solani AG-3PT is the major pathogen associated with potato stem canker and black scurf in Colombia / Rhizoctonia solani GA-3PT es el principal patógeno asociado con el chancro del tallo y la sarna negra de la papa en Colombia  

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Full Text Available SciELO Colombia | Language: English Abstract in spanish El chancro del tallo y la sarna negra de la papa son ocasionados por el hongo basidiomicete Thanatephorus cucumeris (especie anamórfica compleja Rhizoctonia solani). Estas dos enfermedades tienen una distribución global en los cultivos de papa, pero su etiología local es variable, dependiendo de la [...] predominancia de diferentes grupos de anastomosis (GA s) en una localidad dada. Al interior de esta especie compleja se han encontrado varios GA s asociados con el chancro del tallo y la sarna negra, como GA -1, GA -2-1, GA -2-2, GA -3, GA -4, GA -5 y GA -9. Este artículo presenta el estudio más exhaustivo a nivel poblacional realizado en Colombia sobre la distribución de los GA s de R. solani en lotes comerciales de papa. Se examinaron 433 aislamientos colectados entre 2005 y 2009 en las regiones paperas más importantes del país. Los aislamientos fueron asignados a los GA s por PCR usando cebadores específicos para el GA -3 y secuenciamiento del ITS -ADNr e interacciones hifales. El GA -3PT cubrió la mayoría de los aislamientos (88.45%), el GA -2-1 tuvo el 2.54% y los aislamientos restantes correspondieron a cepas binucleadas de R. solani (GA -A, -E, y -I). Las pruebas de patogenicidad sobre diferentes especies de plantas, incluida la papa, evidenciaron que el GA -3PT afecta los tallos de las plantas de la familia Solanácea; en otros hospedantes evaluados el daño fue severo en las raíces pero no en los tallos; el GA -2-1 ocasionó chancros en tallos de plántulas de Solanum tuberosum cv. Capiro y R. raphanistrumi and B. campestris subsp. Rapa, y pudrición de raíces en otras plantas. Los resultados de nuestro estudio indican que el GA -3PT de R. solani es el principal patógeno asociado con las enfermedades del chancro del tallo y la sarna negra de la papa en Colombia Abstract in english Stem canker and black scurf diseases of potatoes are caused by the basidiomycetous fungus Thanatephorus cucumeris (anamorphic species complex Rhizoctonia solani). These diseases have worldwide distribution wherever potato is grown but their etiology varies depending on the predominance of distinct R [...] . solani anastomosis groups (AG s) in a particular area. Within the species complex, several AG s have been associated with stem canker or black scurf diseases, including AG -1, AG -2-1, AG -2-2, AG -3, AG -4, AG -5 and AG -9. This article reports on the most comprehensive population-based study, providing evidence on the distribution of R. solani AG s in Colombian potato fields. A total of 433 isolates were sampled from the main potato cropping areas in Colombia from 2005 to 2009. Isolates were assigned to AG s by conventional PCR assays using specific primers for AG -3, sequencing of the ITS -rDNA and hyphal interactions. Most of the isolates evaluated were assigned to AG -3PT (88.45%), and a few to AG -2-1 (2.54%). The remaining isolates were binucleate Rhizoctonia (AG -A, E, and I). Pathogenicity tests on the stems and roots of different plant species, including the potato, showed that AG -3PT affects the stems of solanaceous plants. In other plant species, damage was severe in the roots, but not the stems. AG -2-1 caused stem canker of Solanum tuberosum cv. Capiro and in R. raphanistrumi and B.campestris subsp. Rapa plantlets and root rot in other plants. The results of our study indicated that R. solani AG -3PT was the principal pathogen associated with potato stem canker and black scurf diseases of potatoes in Colombia

Rosa Lilia, Ferrucho; Johan Manuel, Cifuentes; Paulo, Ceresini; Celsa, García-Domínguez.

215

Rhizoctonia solani AG-3PT is the major pathogen associated with potato stem canker and black scurf in Colombia / Rhizoctonia solani GA-3PT es el principal patógeno asociado con el chancro del tallo y la sarna negra de la papa en Colombia  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish El chancro del tallo y la sarna negra de la papa son ocasionados por el hongo basidiomicete Thanatephorus cucumeris (especie anamórfica compleja Rhizoctonia solani). Estas dos enfermedades tienen una distribución global en los cultivos de papa, pero su etiología local es variable, dependiendo de la [...] predominancia de diferentes grupos de anastomosis (GA s) en una localidad dada. Al interior de esta especie compleja se han encontrado varios GA s asociados con el chancro del tallo y la sarna negra, como GA -1, GA -2-1, GA -2-2, GA -3, GA -4, GA -5 y GA -9. Este artículo presenta el estudio más exhaustivo a nivel poblacional realizado en Colombia sobre la distribución de los GA s de R. solani en lotes comerciales de papa. Se examinaron 433 aislamientos colectados entre 2005 y 2009 en las regiones paperas más importantes del país. Los aislamientos fueron asignados a los GA s por PCR usando cebadores específicos para el GA -3 y secuenciamiento del ITS -ADNr e interacciones hifales. El GA -3PT cubrió la mayoría de los aislamientos (88.45%), el GA -2-1 tuvo el 2.54% y los aislamientos restantes correspondieron a cepas binucleadas de R. solani (GA -A, -E, y -I). Las pruebas de patogenicidad sobre diferentes especies de plantas, incluida la papa, evidenciaron que el GA -3PT afecta los tallos de las plantas de la familia Solanácea; en otros hospedantes evaluados el daño fue severo en las raíces pero no en los tallos; el GA -2-1 ocasionó chancros en tallos de plántulas de Solanum tuberosum cv. Capiro y R. raphanistrumi and B. campestris subsp. Rapa, y pudrición de raíces en otras plantas. Los resultados de nuestro estudio indican que el GA -3PT de R. solani es el principal patógeno asociado con las enfermedades del chancro del tallo y la sarna negra de la papa en Colombia Abstract in english Stem canker and black scurf diseases of potatoes are caused by the basidiomycetous fungus Thanatephorus cucumeris (anamorphic species complex Rhizoctonia solani). These diseases have worldwide distribution wherever potato is grown but their etiology varies depending on the predominance of distinct R [...] . solani anastomosis groups (AG s) in a particular area. Within the species complex, several AG s have been associated with stem canker or black scurf diseases, including AG -1, AG -2-1, AG -2-2, AG -3, AG -4, AG -5 and AG -9. This article reports on the most comprehensive population-based study, providing evidence on the distribution of R. solani AG s in Colombian potato fields. A total of 433 isolates were sampled from the main potato cropping areas in Colombia from 2005 to 2009. Isolates were assigned to AG s by conventional PCR assays using specific primers for AG -3, sequencing of the ITS -rDNA and hyphal interactions. Most of the isolates evaluated were assigned to AG -3PT (88.45%), and a few to AG -2-1 (2.54%). The remaining isolates were binucleate Rhizoctonia (AG -A, E, and I). Pathogenicity tests on the stems and roots of different plant species, including the potato, showed that AG -3PT affects the stems of solanaceous plants. In other plant species, damage was severe in the roots, but not the stems. AG -2-1 caused stem canker of Solanum tuberosum cv. Capiro and in R. raphanistrumi and B.campestris subsp. Rapa plantlets and root rot in other plants. The results of our study indicated that R. solani AG -3PT was the principal pathogen associated with potato stem canker and black scurf diseases of potatoes in Colombia

Rosa Lilia, Ferrucho; Johan Manuel, Cifuentes; Paulo, Ceresini; Celsa, García-Domínguez.

2012-08-01

216

Efeito da solarização do solo, seguida pela aplicação de Trichoderma spp: ou de fungicidas, sobre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4 / Effect of soil solarization, followed or not by the application of Trichoderma spp: or fungicides for the control of Pythium aphanidermatum and Rhizoctonia solani AG-4  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O presente trabalho foi realizado com o objetivo de estudar alternativas para a desinfestação de solos, especialmente considerando a retirada do brometo de metila do mercado. Avaliou-se o efeito da solarização do solo, seguida ou não pela aplicação de isolados de Trichoderma spp. ou de fungicidas, s [...] obre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4, responsáveis por tombamento e podridão de raízes em várias culturas. Dois experimentos foram realizados em Piracicaba, SP (latitude 22º 42' e longitude 47º38'), um em campo aberto e outro no interior de uma casa-de-vegetação vedada, em delineamento em blocos casualizados, em esquema fatorial (2x3), tendo como fatores a solarização (com e sem) e os tratamentos (com fungicida, um isolado de Trichoderma sp. e uma testemunha). Bolsas de náilon contendo solo naturalmente infestado com P. aphanidermatum ou solo contendo propágulos de R. solani AG-4 foram enterradas a 10 cm de profundidade, em parcelas solarizadas ou não, nos dois ambientes. Após 30 dias de solarização, as bolsas foram coletadas e o solo infestado com P. aphanidermatum recebeu os tratamentos: o isolado de Trichoderma sp. IB-26 ou o fungicida metalaxyl + mancozeb. O solo contendo propágulos de R. solani foi tratado com o isolado de Trichoderma sp. IB-17 ou o fungicida pencycuron. As soluções dos fungicidas foram aplicadas na forma de rega. Também foram mantidas testemunhas para ambos os patógenos. Avaliou-se a viabilidade de P. aphanidermatum pelo tombamento de pós-emergência de plântulas de pepino e de R. solani pelo número de plântulas de rabanete sobreviventes ao tombamento de pré e pós-emergência. A solarização, o controle biológico e a solarização seguida pelo controle biológico não promoveram o controle de P. aphanidermatum, obtido apenas com metalaxyl + mancozeb, nos solos solarizados ou não. A solarização aplicada nos dois ambientes controlou R. solani, assim como o fungicida pencycuron, mas não houve efeito sinérgico na associação entre as técnicas. A aplicação do isolado de Trichoderma sp. IB-17 não proporcionou o controle desse patógeno nos solos solarizados ou não. Abstract in english The development of alternative strategies for soil desinfestation with methyl bromide is necessary since the use of this compound faces increasing restrictions worldwide. Therefore the effect of soil solarization, followed by the application of isolates of Trichoderma spp. or fungicides, was evaluat [...] ed for the control of Pythium aphanidermatum and Rhizoctonia solani, both can cause damping-off and root rots of several crops. Two experiments were carried out, one under greenhouse conditions and the other one under field conditions, both in a randomized block design, in factorial scheme (2x3), involving the combination of soil solarization (solarized and non-solarized soils) and the application of chemical or biological treatments, plus controls. Nylon bags containing soil naturally infested with P. aphanidermatum or soil with propagules of R. solani AG-4 were buried at 10 cm soil depth in plots solarized or non-solarized. After 30 days of solarization the bags were collected and the soil infested with P. aphanidermatum was treated with Trichoderma sp. (isolate IB-26) or with the fungicide metalaxyl + mancozeb, whereas the soil containing propagules of R. solani received an isolate of Trichoderma sp. (isolate IB-17) or the fungicide pencycuron. Fungicide suspensions were irrigated over the soil. A control was maintained for the soils infested with both pathogens. Viability of P. aphanidermatum and R. solani was evaluated by post-emergence damping-off of cucumber seedlings and by pre and post-emergence damping-off of radish seedling, respectively. Soil solarization, the biological treatment and the association of both treatments had no effect on the control of P. aphanidermatum, which was achieved only by the treatment with metalaxyl + mancozeb in the solarized

Flávia Rodrigues Alves, Patrício; Hiroshi, Kimati; João, Tessarioli Neto; Ademir, Petenatti; Benedito Camargo, Barros.

217

Efeito da solarização do solo, seguida pela aplicação de Trichoderma spp: ou de fungicidas, sobre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4 Effect of soil solarization, followed or not by the application of Trichoderma spp: or fungicides for the control of Pythium aphanidermatum and Rhizoctonia solani AG-4  

Directory of Open Access Journals (Sweden)

Full Text Available O presente trabalho foi realizado com o objetivo de estudar alternativas para a desinfestação de solos, especialmente considerando a retirada do brometo de metila do mercado. Avaliou-se o efeito da solarização do solo, seguida ou não pela aplicação de isolados de Trichoderma spp. ou de fungicidas, sobre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4, responsáveis por tombamento e podridão de raízes em várias culturas. Dois experimentos foram realizados em Piracicaba, SP (latitude 22º 42' e longitude 47º38', um em campo aberto e outro no interior de uma casa-de-vegetação vedada, em delineamento em blocos casualizados, em esquema fatorial (2x3, tendo como fatores a solarização (com e sem e os tratamentos (com fungicida, um isolado de Trichoderma sp. e uma testemunha. Bolsas de náilon contendo solo naturalmente infestado com P. aphanidermatum ou solo contendo propágulos de R. solani AG-4 foram enterradas a 10 cm de profundidade, em parcelas solarizadas ou não, nos dois ambientes. Após 30 dias de solarização, as bolsas foram coletadas e o solo infestado com P. aphanidermatum recebeu os tratamentos: o isolado de Trichoderma sp. IB-26 ou o fungicida metalaxyl + mancozeb. O solo contendo propágulos de R. solani foi tratado com o isolado de Trichoderma sp. IB-17 ou o fungicida pencycuron. As soluções dos fungicidas foram aplicadas na forma de rega. Também foram mantidas testemunhas para ambos os patógenos. Avaliou-se a viabilidade de P. aphanidermatum pelo tombamento de pós-emergência de plântulas de pepino e de R. solani pelo número de plântulas de rabanete sobreviventes ao tombamento de pré e pós-emergência. A solarização, o controle biológico e a solarização seguida pelo controle biológico não promoveram o controle de P. aphanidermatum, obtido apenas com metalaxyl + mancozeb, nos solos solarizados ou não. A solarização aplicada nos dois ambientes controlou R. solani, assim como o fungicida pencycuron, mas não houve efeito sinérgico na associação entre as técnicas. A aplicação do isolado de Trichoderma sp. IB-17 não proporcionou o controle desse patógeno nos solos solarizados ou não.The development of alternative strategies for soil desinfestation with methyl bromide is necessary since the use of this compound faces increasing restrictions worldwide. Therefore the effect of soil solarization, followed by the application of isolates of Trichoderma spp. or fungicides, was evaluated for the control of Pythium aphanidermatum and Rhizoctonia solani, both can cause damping-off and root rots of several crops. Two experiments were carried out, one under greenhouse conditions and the other one under field conditions, both in a randomized block design, in factorial scheme (2x3, involving the combination of soil solarization (solarized and non-solarized soils and the application of chemical or biological treatments, plus controls. Nylon bags containing soil naturally infested with P. aphanidermatum or soil with propagules of R. solani AG-4 were buried at 10 cm soil depth in plots solarized or non-solarized. After 30 days of solarization the bags were collected and the soil infested with P. aphanidermatum was treated with Trichoderma sp. (isolate IB-26 or with the fungicide metalaxyl + mancozeb, whereas the soil containing propagules of R. solani received an isolate of Trichoderma sp. (isolate IB-17 or the fungicide pencycuron. Fungicide suspensions were irrigated over the soil. A control was maintained for the soils infested with both pathogens. Viability of P. aphanidermatum and R. solani was evaluated by post-emergence damping-off of cucumber seedlings and by pre and post-emergence damping-off of radish seedling, respectively. Soil solarization, the biological treatment and the association of both treatments had no effect on the control of P. aphanidermatum, which was achieved only by the treatment with metalaxyl + mancozeb in the solarized and non-solarized soil. Soil solarization applied in both environments as well as the fungicide pencycu

Flávia Rodrigues Alves Patrício

2007-06-01

218

Efeito da solarização do solo, seguida pela aplicação de Trichoderma spp: ou de fungicidas, sobre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4 / Effect of soil solarization, followed or not by the application of Trichoderma spp: or fungicides for the control of Pythium aphanidermatum and Rhizoctonia solani AG-4  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O presente trabalho foi realizado com o objetivo de estudar alternativas para a desinfestação de solos, especialmente considerando a retirada do brometo de metila do mercado. Avaliou-se o efeito da solarização do solo, seguida ou não pela aplicação de isolados de Trichoderma spp. ou de fungicidas, s [...] obre o controle de Pythium aphanidermatum e de Rhizoctonia solani AG-4, responsáveis por tombamento e podridão de raízes em várias culturas. Dois experimentos foram realizados em Piracicaba, SP (latitude 22º 42' e longitude 47º38'), um em campo aberto e outro no interior de uma casa-de-vegetação vedada, em delineamento em blocos casualizados, em esquema fatorial (2x3), tendo como fatores a solarização (com e sem) e os tratamentos (com fungicida, um isolado de Trichoderma sp. e uma testemunha). Bolsas de náilon contendo solo naturalmente infestado com P. aphanidermatum ou solo contendo propágulos de R. solani AG-4 foram enterradas a 10 cm de profundidade, em parcelas solarizadas ou não, nos dois ambientes. Após 30 dias de solarização, as bolsas foram coletadas e o solo infestado com P. aphanidermatum recebeu os tratamentos: o isolado de Trichoderma sp. IB-26 ou o fungicida metalaxyl + mancozeb. O solo contendo propágulos de R. solani foi tratado com o isolado de Trichoderma sp. IB-17 ou o fungicida pencycuron. As soluções dos fungicidas foram aplicadas na forma de rega. Também foram mantidas testemunhas para ambos os patógenos. Avaliou-se a viabilidade de P. aphanidermatum pelo tombamento de pós-emergência de plântulas de pepino e de R. solani pelo número de plântulas de rabanete sobreviventes ao tombamento de pré e pós-emergência. A solarização, o controle biológico e a solarização seguida pelo controle biológico não promoveram o controle de P. aphanidermatum, obtido apenas com metalaxyl + mancozeb, nos solos solarizados ou não. A solarização aplicada nos dois ambientes controlou R. solani, assim como o fungicida pencycuron, mas não houve efeito sinérgico na associação entre as técnicas. A aplicação do isolado de Trichoderma sp. IB-17 não proporcionou o controle desse patógeno nos solos solarizados ou não. Abstract in english The development of alternative strategies for soil desinfestation with methyl bromide is necessary since the use of this compound faces increasing restrictions worldwide. Therefore the effect of soil solarization, followed by the application of isolates of Trichoderma spp. or fungicides, was evaluat [...] ed for the control of Pythium aphanidermatum and Rhizoctonia solani, both can cause damping-off and root rots of several crops. Two experiments were carried out, one under greenhouse conditions and the other one under field conditions, both in a randomized block design, in factorial scheme (2x3), involving the combination of soil solarization (solarized and non-solarized soils) and the application of chemical or biological treatments, plus controls. Nylon bags containing soil naturally infested with P. aphanidermatum or soil with propagules of R. solani AG-4 were buried at 10 cm soil depth in plots solarized or non-solarized. After 30 days of solarization the bags were collected and the soil infested with P. aphanidermatum was treated with Trichoderma sp. (isolate IB-26) or with the fungicide metalaxyl + mancozeb, whereas the soil containing propagules of R. solani received an isolate of Trichoderma sp. (isolate IB-17) or the fungicide pencycuron. Fungicide suspensions were irrigated over the soil. A control was maintained for the soils infested with both pathogens. Viability of P. aphanidermatum and R. solani was evaluated by post-emergence damping-off of cucumber seedlings and by pre and post-emergence damping-off of radish seedling, respectively. Soil solarization, the biological treatment and the association of both treatments had no effect on the control of P. aphanidermatum, which was achieved only by the treatment with metalaxyl + mancozeb in the solarized

Flávia Rodrigues Alves, Patrício; Hiroshi, Kimati; João, Tessarioli Neto; Ademir, Petenatti; Benedito Camargo, Barros.

2007-06-01

219

Respuesta al glifosato de un aislamiento de Rhizoctonia solani agente causal del anublo de la vaina del arroz, y de cuatro aislamientos de Trichoderma, bajo condiciones in vitro In vitro response of one isolate of Rhizoctonia solani, the pathogen of the rice sheath blight and four isolates of Trichoderma to glyphosate  

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Full Text Available El añublo de la vaina del arroz (Orysa saliva L., cuyo agente causal es Rhizoctonia solani Kuhn, es una de las enfermedades más importantes en el cultivo del arroz en Colombia. En los cultivos de arroz con frecuencia se aplica glifosato ((ácido N-(fosfonometil glicina para controlar las malezas, particularmente el arroz rojo (O. saliva, antes de la siembra del arroz. Observaciones de campo anteriores parecían indicar relación entre el uso intensivo del glifosato y el incremento en la incidencia del añublo de la vaina del arroz. Por tanto, se propuso el presente trabajo con el fin de dilucidar los posibles efectos del glifosato sobre R. solani y Trichoderma sp., conocido éste como antagonista de R. solani. Se determinó, bajo condiciones de laboratorio, el efecto del glifosato en el crecimiento, en medio líquido y sólido PDA, de R. solani y de Trichoderma. Se encontró que la dosis más alta de glifosato sin efecto detrimental sobre R. solani, fue de 300 mg/L y la dosis más baja del herbicida que
causó la mayor inhibición del crecimiento del hongo fue
de 2500 mg/L. Por otra parte, no se encontró que el glifosato
estimulara el crecimiento de R. solani. En teoría, en una aplicación comercial de glifosato de 1,5 Kg ia/ha y asperjando directamente al suelo sin vegetación, el glifosato en el suelo estaría a una concentración de 0,75 mg/Kg de suelo (suponiendo que la capa arable de una hectárea de suelo pesa 2.000.000 de Kg; por tanto, la concentración de glifosato después de una aplicación comercial, está muy por debajo de la concentración a la cual se inicia la reducción del crecimiento de R. solani. Por su parte, la respuesta de Trichoderma al glifosato fue similar a la de R. solani; además, se encontró que el glifosato no afecta la capacidad antagonista de Trichoderma sobre R. sotaní. Estos resultados no apoyan la hipótesis que el glifosato, bajo las condiciones de uso en cultivos de arroz para el control de las malezas, estuviera afectando el crecimiento de R. solani o de su antagonista Trichoderma. Una posible relación entre el uso intensivo del herbicida y la incidencia del añublo de la vaina del arroz, debería investigarse en términos de supervivencia
y germinación de esclerocios del patógeno.
Rhizoctonia solani Kuhn is the causal agent ofthe sheath
blight of rice (Orysa saliva L., one of the most important
rice diseases in Colombia. G1yphosate (N-phosphonomethyl
glicine acid is sprayed in rice fields as a preplant herbicide, specially aimed at red rice (O. saliva. Preliminary field observations in Tolima, Colombia suggested a relationship between intensive use of glyphosate and sheath blight incidence. Thus, the present study was undertaken to shed light on the effect of glyphosate on R. solani and Thrichoderma sp., a.putative antagonist, under laboratory conditions. The effect of the herbicide was assessed on the growth ofR. solani in summerged culture and solid media and of Thrichoderma on solid media. R. sotaní withstood up to 300 mg L-! without expressing reduction in growth, Increasing concentrations of the herbicide caused growth reduction, and the detrimental effect reached a plateau at 2500 mg L-1. Rhizoctonia growth was not enhanced at any herbicide concentration. The expected concentration of glyphosate in the soil after spraying at commercial dosages would be O, 75 mg Kg', which is well below the observed in vitro threshold. The response of Thrichoderma was similar to that of R. sotaní. Glyphosate did not affect the antagonistic ability of Thrichoderma against R. solani. These results do not support the view that glyphosate, as an herbicide treatment in rice
field, may affect in any way the population densities of R.
sotaní or its antagonist Thrichoderma sp. Therefore, the
postulated connection between intensive herbicide use
and increased sheath blight incidence is not substantiated
on mycelial growth alone. T

Vargas de Álvarez Amparo

2002-08-01

220

Reacción de genotipos de frijol a Fusarium spp. y Rhizoctonia solani bajo condiciones de campo e invernadero / Reaction of common bean genotypes to Fusarium spp. y Rhizoctonia solani under field and greenhose conditions  

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Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Las pudriciones de raíz inducidas por R. solani y Fusarium spp. afectan al cultivo de frijol (Phaseolus vulgaris L.) en el altiplano de México. Para identificar genotipos de frijol resistentes a ambos hongos bajo condiciones de invernadero y campo, se realizaron dos experimentos en 2001. En campo, b [...] ajo condiciones de temporal, se sembraron 15 genotipos el 24 de julio, en suelo naturalmente infestado con hongos inductores de pudriciones de raíz, en Texcoco, Estado de México. Durante el ciclo del cultivo se determinó la incidencia y severidad de la enfermedad en las etapas fenológicas V3, R5, R7 y R8; además, se registraron temperatura ambiente y precipitación pluvial diaria. Los mismos genotipos se sembraron en invernadero el 27 de julio de 2001 en macetas con suelo del mismo sitio, las determinaciones realizadas en ambos ensayos fueron similares. Se tomaron muestras de tejido vegetal para el aislamiento e identificación de los hongos causantes de pudriciones de raíz; ambos, R. solani y Fusarium spp. se recuperaron. En campo, se observaron pudriciones de raíz durante todo el ciclo, con la mayor severidad en las etapas R5 y R7, sin que se observaran genotipos inmunes. Negro Tacaná mostró resistencia intermedia a Fusarium spp. y G 12729 (genotipo silvestre) fue resistente en las primeras etapas fenológicas. En invernadero, ningún genotipo mostró un patrón de resistencia durante el ciclo. En campo, el ataque de R. solani fue menos severo que el de Fusarium spp., mientras que en invernadero el ataque de R. solani fue más alto. En campo, los genotipos Pinto Villa, Wisc RRR, PI 203958 y BAT 477 mostraron resistencia intermedia y fueron consistentes en su respuesta a ambos hongos, pero en invernadero mostraron susceptibilidad. La incidencia y la severidad de los patógenos mostraron diferencias relacionadas con las condiciones climáticas registradas durante el ciclo del cultivo. Abstract in english The root rot induced damage caused by R. solani and Fusarium spp. affects common bean (Phaseolus vulgaris L.) production at the highlands of Mexico. To identify bean genotypes resistant to both fungi, two experiments were conductedunderfieldand greenhouse conditions. In the field, under rainfed cond [...] itions, 15 bean genotypes were planted on July 24 2001, at Texcoco, state of Mexico. Incidence and attack severity were determined at the phenological stages V3, R5, R7 and R8; also, daily temperature and precipitation were recorded. The same genotypes were planted under greenhouse conditions on July 27th, 2001 in pots with soil from the same site. Plant samples were collected from all genotypes for isolation and identification of fungi causing root rots. Both,R. solani and Fusarium spp. were recovered. Under field conditions, root rots were observed throughout the cycle, with the greatest severity at the R5 and R7 stages, no immune genotypes were observed. Cultivar Negro Tacana showed intermediate resistance to Fusarium spp. and G 12729 (a wild genotype) was resistant during the early phenological stages. Under greenhouse conditions, any genotype showed a consistent resistance pattern during the cycle. Atthe field, the attack by R. solani was less severe than that of Fusarium spp., whereas in the greenhouse the attack R. solani was severe. Atthe field, cultivars Pinto Villa, Wisc RRR, PI 203,958 and BAT 477 were intermediate and consistent in its response to both fungi; however, were susceptible in the greenhouse. The disease incidence and severity on the genotypes showed differences related to climatic conditions registered during the growth cycle.

Rosa, Navarrete-Maya; Evangelina, Trejo-Albarrán; Jorge, Navarrete-Maya; José Manuel, Prudencio-Sains; Jorge Alberto, Acosta Gallegos.

 
 
 
 
221

Evaluación del método de conservación en papel de filtro en dos cepas de Bacillus subtilis Cohn mediante la actividad antagónica frente a Rhizoctonia solani Kühn / Evaluation of Filter Paper Disks Preserving Method in Two Bacillus subtilis Cohn. Strains by Antagonistic Activity on Rhizoctonia solani Kühn  

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Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish Se evaluó la actividad antagónica de dos cepas de Bacillus subtilis conservadas en discos de papel de filtro a 4°C por un período de tres años. Se escogieron las cepas del género B. subtilis: Bs-21 y Bs-42, aisladas del suelo, autóctonas de Cuba, y antagónicas de la cepa Rs-10 de Rhizoctonia solani. [...] Se determinó la viabilidad, pureza y actividad antagónica de cinco colonias de Bs-42 y una de Bs-21, escogidas al azar y cultivadas en agar nutriente. Las colonias seleccionadas se evaluaron por el método de enfrentamiento dual en papa dextrosa agar, después de 96 h de incubación a 30°C. Ambas cepas presentaron una viabilidad de 108 UFC/mL. Los cultivos mantuvieron la pureza, las características morfológicas y respuesta positiva a la tinción de Gram, comparadas con la cepa de B. subtilis ATCC 6633. Todas las colonias seleccionadas inhibieron el crecimiento micelial de la cepa Rs-10 de R. solani, no así la de referencia. El análisis de varianza realizado mostró diferencias significativas en el porcentaje de inhibición de las colonias ensayadas. La cepa Bs-21 resultó ser la de menor inhibición con el 78%, y Bs-421 y Bs-422 las de mayor porcentaje con el 98%. Abstract in english Antagonistic activity of two Bacillus subtilis strains preserved in filter paper disks at 4°C for a period of three years was evaluated. Strains Bs-21 and Bs-42, isolated from Cuban soil and antagonists to Rhizoctonia solani Rs-10 were choiced. Five colonies from Bs-42 and one from Bs-21, randomly s [...] elected were growth in nutrient agar. The antagonism was compared by dual culture method in PDA after 96 h at 30°C. Viability of both strains was 108 CFU/mL. Selected colonies kept purity, morphological characteristics and positive response to Gram stain compared with B. subtilis ATCC 6633. All selected colonies inhibited mycelial growth of R. solani Rs-10, but not the reference strain. Strain Bs-21 had the lower inhibition (78%) while Bs-421 and Bs-422 had the higher percent (98%). Variance analysis showed significant differences in the percentage of inhibition exhibited by tested colonies.

Acenet I, Sosa López; Victoria, Pazos Álvarez-Rivera; Giovanni, Borges Marín; Marleny, González García; Enrique, Ponce Grijuela.

222

Evaluación del método de conservación en papel de filtro en dos cepas de Bacillus subtilis Cohn mediante la actividad antagónica frente a Rhizoctonia solani Kühn / Evaluation of Filter Paper Disks Preserving Method in Two Bacillus subtilis Cohn. Strains by Antagonistic Activity on Rhizoctonia solani Kühn  

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Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish Se evaluó la actividad antagónica de dos cepas de Bacillus subtilis conservadas en discos de papel de filtro a 4°C por un período de tres años. Se escogieron las cepas del género B. subtilis: Bs-21 y Bs-42, aisladas del suelo, autóctonas de Cuba, y antagónicas de la cepa Rs-10 de Rhizoctonia solani. [...] Se determinó la viabilidad, pureza y actividad antagónica de cinco colonias de Bs-42 y una de Bs-21, escogidas al azar y cultivadas en agar nutriente. Las colonias seleccionadas se evaluaron por el método de enfrentamiento dual en papa dextrosa agar, después de 96 h de incubación a 30°C. Ambas cepas presentaron una viabilidad de 108 UFC/mL. Los cultivos mantuvieron la pureza, las características morfológicas y respuesta positiva a la tinción de Gram, comparadas con la cepa de B. subtilis ATCC 6633. Todas las colonias seleccionadas inhibieron el crecimiento micelial de la cepa Rs-10 de R. solani, no así la de referencia. El análisis de varianza realizado mostró diferencias significativas en el porcentaje de inhibición de las colonias ensayadas. La cepa Bs-21 resultó ser la de menor inhibición con el 78%, y Bs-421 y Bs-422 las de mayor porcentaje con el 98%. Abstract in english Antagonistic activity of two Bacillus subtilis strains preserved in filter paper disks at 4°C for a period of three years was evaluated. Strains Bs-21 and Bs-42, isolated from Cuban soil and antagonists to Rhizoctonia solani Rs-10 were choiced. Five colonies from Bs-42 and one from Bs-21, randomly s [...] elected were growth in nutrient agar. The antagonism was compared by dual culture method in PDA after 96 h at 30°C. Viability of both strains was 108 CFU/mL. Selected colonies kept purity, morphological characteristics and positive response to Gram stain compared with B. subtilis ATCC 6633. All selected colonies inhibited mycelial growth of R. solani Rs-10, but not the reference strain. Strain Bs-21 had the lower inhibition (78%) while Bs-421 and Bs-422 had the higher percent (98%). Variance analysis showed significant differences in the percentage of inhibition exhibited by tested colonies.

Acenet I, Sosa López; Victoria, Pazos Álvarez-Rivera; Giovanni, Borges Marín; Marleny, González García; Enrique, Ponce Grijuela.

2011-03-01

223

Influence of Weather and Soil Parameters on Development of Wet Root Rot in Pulse Crops and Virulence Analysis of Rhizoctonia solani Isolates  

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Full Text Available Wet root rot caused by Rhizoctonia solani Kühn in pulse crops was favored by wide range of soil parameters like temperature, humidity, pH, electric conductivity and soil texture. The areas surveyed for the collection of the isolates showing variable atmospheric temperature and relative humidity and low to medium levels of soil organic carbon and high level of available phosphorus influenced the development of the disease incidence from 2-48%. Seventy three cultivars of mungbean, twenty eight cultivars of urdbean and eight cultivars of cowpea were evaluated against virulent isolate of R. solani (RASC 30 to design a set of differential cultivars for virulence analysis. Two cultivars of urdbean, namely, NDU3-4 and IPU2-14, one cultivar of mungbean, namely, HUM 1 and three cultivars of cowpea, namely, V240, V585 and DCP7 showed resistant reactions. Four cultivars of urdbean, namely, TU94-2, KU323, KUG216 and B3-8-8, one cultivar of mungbean, namely, PDM54 and two cultivars of cowpea, namely, V578 and DCP13 were moderately resistant against the pathogen. The virulence analysis of 90 isolates of the pathogen representing 7 anastomosis groups (AGs isolated from pulse crops of 16 agro-ecological regions of India on a set of differential cultivars, namely, HUM 1, PDM 54 and Pusa Vishal of mungbean, NDU 3-4, KU 323, Uttara of urdbean and V 240, V 578 and Pusa Sukomal of cowpea grouped the isolates into five pathotypes. The differential cultivar for each pathotype was identified. The pathotypes were not corresponding to the AG type of the isolates. Except one pathotype (isolate RMPG28 belonging to AG2-3, each pathotype had the isolates from different AGs.

S. C. Dubey

2012-10-01

224

Métodos de evaluación y reacción de cultivares para resistencia al añublo de la vaina del arroz causado por Rhizoctonia solani AG-1 IA / Evaluation methods and cultivars reaction for resistance to the rice sheath blight caused by Rhizoctonia solani AG-1 IA  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish El arroz (Oryza sativa L.) en Venezuela, es afectado por el añublo de la vaina causado por Rhizoctonia solani (Teleomorfo = Thanatephorus cucumeris). No existe resistencia completa ante esta enfermedad. Por ello, los programas de mejoramiento genético deben evaluar un alto número de cultivares para [...] seleccionar aquellos cuantitativamente mejores en resistencia. Los objetivos fueron comparar métodos de evaluación de resistencia y la reacción de cultivares para resistencia al añublo de la vaina del arroz causado por R. solani AG-1 IA. Los métodos de evaluación usados fueron microcámaras y bola de micelio en umbráculo, la prueba de cinetina en laboratorio y la infestación con arroz colonizado bajo condiciones de campo. Se evaluaron 23 genotipos de arroz, incluyendo variedades testigo. Tres haplotipos de R. solani, previamente caracterizados, fueron utilizados para las inoculaciones. Los ensayos fueron de bloques completos al azar con tres repeticiones. La efectividad de los ensayos se determinó con base a la discriminación de los testigos de reacción conocida y a la mejor correlación de los métodos de laboratorio y umbráculo con los resultados de campo. El método de microcámaras, combinado con el aislado de R. solani A5B4 (64), presentó la mejor correlación con los resultados de campo (r = 0,50 en promedio), seguido por el método de bola de micelio (r = 0,49, promedio). Los cultivares testigo ‘Tetep’ (resistente) y ‘Lemont’ (susceptible) fueron consistentes en los ensayos. El análisis de componentes principales identificó los genotipos CT15150-M-11-4-3-2-M (derivado de un cruce con O. glaberrima), ‘SD20A’ y ‘D-Sativa’ con los mejores niveles de resistencia. Estos resultados indican la existencia de métodos confiables para evaluar el añublo de la vaina y de cultivares adaptados con resistencia a la enfermedad. Abstract in english The rice (Oryza sativa L.), in Venezuela, is affected by sheath blight caused by Rhizoctonia solani (teleomorph = Thanatephorus cucumeris). No complete resistance has been found in the world. In consequence, breeding programs should evaluate many cultivars for selecting those with the best quantitat [...] ive level of resistance. The objectives were to compare methods of evaluation and cultivars reaction for resistance to the sheath blight caused by R. solani AG-1 IA. The evaluation methods were microchamber and mycelium ball in greenhouse conditions, kinetin test in laboratory and colonized rice infestation under field conditions. The cultivars were 23 genotypes of rice, including control varieties. Three haplotypes of R. solani, previously characterized, were used for the inoculations. The experimental designs were randomized complete block with three replications. The effectiveness of the trials was determined based on the discrimination of controls with well-known reaction and the best correlation of the laboratory and greenhouse methods with the field results. The method of microchamber using the isolate A5B4 (64) had the best correlation with field results (r = 0.50 on average), followed by the method of ball mycelium (r = 0.49, on average). The control cultivars 'Tetep' (resistant) and 'Lemont' (susceptible) were consistent across the experiments. The principal component analysis identified the genotypes CT15150-M-11-4-3-2-M (derived from a cross with O. glaberrima), 'SD20A' and 'D-Sativa' with the best levels of resistance. These results indicate the existence of reliable methods to evaluate this disease and adapted cultivars with resistance to rice sheath blight.

Alex, González-Vera; Eduardo, Graterol; Brígida, Borges; Francis, Hernández.

225

Métodos de evaluación y reacción de cultivares para resistencia al añublo de la vaina del arroz causado por Rhizoctonia solani AG-1 IA Evaluation methods and cultivars reaction for resistance to the rice sheath blight caused by Rhizoctonia solani AG-1 IA  

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Full Text Available El arroz (Oryza sativa L. en Venezuela, es afectado por el añublo de la vaina causado por Rhizoctonia solani (Teleomorfo = Thanatephorus cucumeris. No existe resistencia completa ante esta enfermedad. Por ello, los programas de mejoramiento genético deben evaluar un alto número de cultivares para seleccionar aquellos cuantitativamente mejores en resistencia. Los objetivos fueron comparar métodos de evaluación de resistencia y la reacción de cultivares para resistencia al añublo de la vaina del arroz causado por R. solani AG-1 IA. Los métodos de evaluación usados fueron microcámaras y bola de micelio en umbráculo, la prueba de cinetina en laboratorio y la infestación con arroz colonizado bajo condiciones de campo. Se evaluaron 23 genotipos de arroz, incluyendo variedades testigo. Tres haplotipos de R. solani, previamente caracterizados, fueron utilizados para las inoculaciones. Los ensayos fueron de bloques completos al azar con tres repeticiones. La efectividad de los ensayos se determinó con base a la discriminación de los testigos de reacción conocida y a la mejor correlación de los métodos de laboratorio y umbráculo con los resultados de campo. El método de microcámaras, combinado con el aislado de R. solani A5B4 (64, presentó la mejor correlación con los resultados de campo (r = 0,50 en promedio, seguido por el método de bola de micelio (r = 0,49, promedio. Los cultivares testigo ‘Tetep’ (resistente y ‘Lemont’ (susceptible fueron consistentes en los ensayos. El análisis de componentes principales identificó los genotipos CT15150-M-11-4-3-2-M (derivado de un cruce con O. glaberrima, ‘SD20A’ y ‘D-Sativa’ con los mejores niveles de resistencia. Estos resultados indican la existencia de métodos confiables para evaluar el añublo de la vaina y de cultivares adaptados con resistencia a la enfermedad.The rice (Oryza sativa L., in Venezuela, is affected by sheath blight caused by Rhizoctonia solani (teleomorph = Thanatephorus cucumeris. No complete resistance has been found in the world. In consequence, breeding programs should evaluate many cultivars for selecting those with the best quantitative level of resistance. The objectives were to compare methods of evaluation and cultivars reaction for resistance to the sheath blight caused by R. solani AG-1 IA. The evaluation methods were microchamber and mycelium ball in greenhouse conditions, kinetin test in laboratory and colonized rice infestation under field conditions. The cultivars were 23 genotypes of rice, including control varieties. Three haplotypes of R. solani, previously characterized, were used for the inoculations. The experimental designs were randomized complete block with three replications. The effectiveness of the trials was determined based on the discrimination of controls with well-known reaction and the best correlation of the laboratory and greenhouse methods with the field results. The method of microchamber using the isolate A5B4 (64 had the best correlation with field results (r = 0.50 on average, followed by the method of ball mycelium (r = 0.49, on average. The control cultivars 'Tetep' (resistant and 'Lemont' (susceptible were consistent across the experiments. The principal component analysis identified the genotypes CT15150-M-11-4-3-2-M (derived from a cross with O. glaberrima, 'SD20A' and 'D-Sativa' with the best levels of resistance. These results indicate the existence of reliable methods to evaluate this disease and adapted cultivars with resistance to rice sheath blight.

Alex González-Vera

2011-04-01

226

Métodos de evaluación y reacción de cultivares para resistencia al añublo de la vaina del arroz causado por Rhizoctonia solani AG-1 IA / Evaluation methods and cultivars reaction for resistance to the rice sheath blight caused by Rhizoctonia solani AG-1 IA  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish El arroz (Oryza sativa L.) en Venezuela, es afectado por el añublo de la vaina causado por Rhizoctonia solani (Teleomorfo = Thanatephorus cucumeris). No existe resistencia completa ante esta enfermedad. Por ello, los programas de mejoramiento genético deben evaluar un alto número de cultivares para [...] seleccionar aquellos cuantitativamente mejores en resistencia. Los objetivos fueron comparar métodos de evaluación de resistencia y la reacción de cultivares para resistencia al añublo de la vaina del arroz causado por R. solani AG-1 IA. Los métodos de evaluación usados fueron microcámaras y bola de micelio en umbráculo, la prueba de cinetina en laboratorio y la infestación con arroz colonizado bajo condiciones de campo. Se evaluaron 23 genotipos de arroz, incluyendo variedades testigo. Tres haplotipos de R. solani, previamente caracterizados, fueron utilizados para las inoculaciones. Los ensayos fueron de bloques completos al azar con tres repeticiones. La efectividad de los ensayos se determinó con base a la discriminación de los testigos de reacción conocida y a la mejor correlación de los métodos de laboratorio y umbráculo con los resultados de campo. El método de microcámaras, combinado con el aislado de R. solani A5B4 (64), presentó la mejor correlación con los resultados de campo (r = 0,50 en promedio), seguido por el método de bola de micelio (r = 0,49, promedio). Los cultivares testigo ‘Tetep’ (resistente) y ‘Lemont’ (susceptible) fueron consistentes en los ensayos. El análisis de componentes principales identificó los genotipos CT15150-M-11-4-3-2-M (derivado de un cruce con O. glaberrima), ‘SD20A’ y ‘D-Sativa’ con los mejores niveles de resistencia. Estos resultados indican la existencia de métodos confiables para evaluar el añublo de la vaina y de cultivares adaptados con resistencia a la enfermedad. Abstract in english The rice (Oryza sativa L.), in Venezuela, is affected by sheath blight caused by Rhizoctonia solani (teleomorph = Thanatephorus cucumeris). No complete resistance has been found in the world. In consequence, breeding programs should evaluate many cultivars for selecting those with the best quantitat [...] ive level of resistance. The objectives were to compare methods of evaluation and cultivars reaction for resistance to the sheath blight caused by R. solani AG-1 IA. The evaluation methods were microchamber and mycelium ball in greenhouse conditions, kinetin test in laboratory and colonized rice infestation under field conditions. The cultivars were 23 genotypes of rice, including control varieties. Three haplotypes of R. solani, previously characterized, were used for the inoculations. The experimental designs were randomized complete block with three replications. The effectiveness of the trials was determined based on the discrimination of controls with well-known reaction and the best correlation of the laboratory and greenhouse methods with the field results. The method of microchamber using the isolate A5B4 (64) had the best correlation with field results (r = 0.50 on average), followed by the method of ball mycelium (r = 0.49, on average). The control cultivars 'Tetep' (resistant) and 'Lemont' (susceptible) were consistent across the experiments. The principal component analysis identified the genotypes CT15150-M-11-4-3-2-M (derived from a cross with O. glaberrima), 'SD20A' and 'D-Sativa' with the best levels of resistance. These results indicate the existence of reliable methods to evaluate this disease and adapted cultivars with resistance to rice sheath blight.

Alex, González-Vera; Eduardo, Graterol; Brígida, Borges; Francis, Hernández.

2011-04-01

227

Detection of trypsin inhibitor in seeds of Eucalyptus urophylla and its influence on the in vitro growth of the fungi Pisolithus tinctorius and Rhizoctonia solani Descoberta de inibidor de tripsina em sementes de Eucalyptus urophylla e sua influência sobre o crescimento in vitro dos fungos Pisolithus tinctorius e Rhizoctonia solani  

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Full Text Available Inhibitors of plant proteases can regulate the hydrolysis of proteins inside the cells and also participate in the mechanisms of plant defense against herbivore insects and pathogens. Here, we demonstrated that seeds of Eucalyptus urophylla exhibit activities of trypsin and papain inhibitors, two proteases commonly found in living cells. Low amounts of proteins of the crude protein extract of seeds and fractions partially purified by gel filtration, with inhibitory activity against trypsin, inhibited in vitro the mycelial growth of a compatible isolate of the ectomycorrhizal fungus Pisolithus tinctorius and allowed an unsatisfactory growth of another isolate from Pinus taeda, considered incompatible for this eucalyptus species. The same amounts of inhibitory proteins, when tested in vitro on the pathogen Rhizoctonia solani, did not exhibit any effect on the growth of the pathogen. These results indicate the existence of proteases inhibitors in seeds of E. urophylla which could influence the complex biochemical system that differentiates mechanisms of symbiosis and pathogenicity between plants and microorganisms.Os inibidores de proteases de plantas podem regular a hidrólise de proteínas no interior celular e também participar de seus mecanismos de defesa contra insetos herbívoros e patógenos. No presente trabalho, nós demonstramos que sementes de Eucalyptus urophylla apresentam atividades de inibidores de tripsina e papaína, duas proteases comumente encontradas em seres vivos. Pequenas quantidades de proteínas do extrato protéico bruto de sementes e de frações parcialmente purificadas por filtração em gel, com atividade inibitória de tripsina, inibiram o crescimento micelial in vitro de um isolado compatível do fungo ectomicorrízico Pisolithus tinctorius e permitiram um crescimento insatisfatório de outro isolado de Pinus taeda, considerado compatível para esta espécie de eucalipto. As mesmas concentrações de proteínas, quando testadas in vitro sobre o patógeno Rhizoctonia solani, não demonstraram qualquer efeito sobre seu crescimento. Estes resultados indicam a existência de inibidores de proteases em sementes de E. urophylla, os quais poderiam influenciar o complexo sistema bioquímico que diferencia mecanismos de simbiose e patogenicidade entre plantas e microrganismos.

Célia Regina Tremacoldi

2002-12-01

228

Characterization of genes involved in biosynthesis of a novel antibiotic from Burkholderia cepacia BC11 and their role in biological control of Rhizoctonia solani  

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Genetic manipulation of fluorescent pseudomonads has provided major insight into their production of antifungal molecules and their role in biological control of plant disease. Burkholderia cepacia also produces antifungal activities, but its biological control activity is much less well characterized, in part due to difficulties in applying genetic tools. Here the authors report genetic and biochemical characterization of a soil isolate of B. cepacia relating to its production of an unusual antibiotic that is very active against a variety of soil fungi. Purification and preliminary structural analyses suggest that this antibiotic (called AFC-BC11) is a novel lipopeptide associated largely with the cell membrane. Analysis of conditions for optimal production of AFC-BC11 indicated stringent environmental regulation of its synthesis. Furthermore, the authors show that production of AFC-BC11 is largely responsible for the ability of B. cepacia BC11 to effectively control the damping-Off of cotton caused by the fungal pathogen Rhizoctonia solani in a gnotobiotic system. Using Tn5 mutagenesis, they identified, cloned, and characterized a region of the genome of strain BC11 that is required for production of this antifungal metabolite. DNA sequence analysis suggested that this region encodes proteins directly involved in the production of a nonribosomally synthesized lipopeptide.

Kang, Y.; Carlson, R.; Tharpe, W.; Schell, M.A. [Univ. of Georgia, Athens, GA (United States)

1998-10-01

229

Co-expression of RCH10 and AGLU1 confers rice resistance to fungal sheath blight Rhizoctonia solani and blast Magnorpathe oryzae and reveals impact on seed germination.  

Science.gov (United States)

Rice sheath blight and blast caused by Rhizoctonia solani Kühn and Magnorpathe oryzae respectively, are the two most destructive fungal diseases in rice. With no genetic natural traits conferring resistance to sheath blight, transgenic manipulation provides an obvious approach. In this study, the rice basic chitinase gene (RCH10) and the alfalfa ?-1,3-glucanase gene (AGLU1) were tandemly inserted into transformation vector pBI101 under the control of 35S promoter with its enhancer sequence to generate a double-defense gene expression cassette pZ100. The pZ100 cassette was transformed into rice (cv. Taipei 309) by Agrobacterium-mediated transformation. More than 160 independent transformants were obtained and confirmed by PCR. Northern analysis of inheritable progenies revealed similar levels of both RCH10 and AGLU1 transcripts in the same individuals. Disease resistance to both sheath blight and blast was challenged in open field inoculation. Immunogold detection revealed that RCH10 and AGLU1 proteins were initially located mainly in the chloroplasts and were delivered to the vacuole and cell wall upon infection, suggesting that these subcellular compartments act as the gathering and execution site for these anti-fungal proteins. We also observed that transgenic seeds display lower germination rate and seedling vigor, indicating that defense enhancement might be achieved at the expense of development. PMID:24197785

Mao, Bizeng; Liu, Xuehui; Hu, Dongwei; Li, Debao

2014-04-01

230

A simple method based on laboratory inoculum and field inoculum for evaluating potato resistance to black scurf caused by Rhizoctonia solani.  

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A two-step method was developed to evaluate potato resistance to black scurf caused by Rhizoctonia solani. Tuber piece inoculum was first conducted in the laboratory, which was also first reported in this study. After inoculation with pathogen discs and culture for 48 h, the necrotic spots on the inoculated potato pieces were generated and measured by the crossing method. Further evaluation was conducted through field experiments using a wheat bran inoculum method. The wheat bran inoculum was placed into the pit dispersedly and surrounded seed tubers. Each cultivar or line was subjected to five treatments of 0-, 2-, 3-, 4-, and 5-g soil inoculum. The results showed that 2-4 g of wheat bran inoculum was the optimum for identifying tuber black scurf resistance. The laboratory scores positively correlated with the incidence and severity of black scurf in the field. According to the results in the laboratory, relatively resistant cultivars could be selected for further estimation of tuber black scurf resistance in field experiments. It is a practical and effective screening method for rapid identification of resistant potato germplasm, which can reduce workload in the field, shorten time required for identification. PMID:24987302

Zhang, Xiao-Yu; Yu, Xiao-Xia; Yu, Zhuo; Xue, Yu-Feng; Qi, Li-Peng

2014-06-01

231

Pelargonium graveolens L'Her. and Artemisia arborescens L. essential oils: chemical composition, antifungal activity against Rhizoctonia solani and insecticidal activity against Rhysopertha dominica.  

Science.gov (United States)

The chemical composition of the Pelargonium graveolens essential oil allowed the identification of 15 compounds (93.86% of the total essential oil). The major fractions were citronellol (35%) and geraniol (28.8%). The chemical composition of the Artemisia arborescens essential oil revealed twenty-one compounds representing 93.57% of the total essential oil. The main compounds were chamazulene (31.9%) and camphor (25.8%). The insecticidal effects were tested towards the insect Rhysopertha dominica. Results revealed that these two essential oils were highly effective against R. dominica at the dose of 50?µL on Petri dish of 8.5?cm of diameter. The antifungal activity was evaluated against Rhizoctonia solani and results showed that both of the essential oils were highly active at a dose of 12.5?µL/20?mL of PDA. Moreover, the inhibitory effect of P. graveolens essential oil was evidenced as stronger than that of the A. arborescens oil for all the tested doses. PMID:22840199

Bouzenna, Hafsia; Krichen, Lamia

2013-01-01

232

Importancia del método estadístico para el cálculo de la CE50 y CE95 de algunos isotiocianatos evaluados contra Rhizoctonia solani Kühn / Importance of the statistical method applied to calculate the EC50 and EC95 of some isothiocyanates evaluated against Rhizoctonia solani Kühn  

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Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish En el marco de la evaluación del efecto de algunos isotiocianatos (ITC) sobre el crecimiento de Rhizoctonia solani Kühn, la presente investigación establece también si el método estadístico utilizado determina diferencias considerables en los valores de la concentración efectiva media (CE50) y la co [...] ncentración efectiva 95 (CE95) de estos compuestos. Para ello se realizó un experimento in vitro, y se estimaron dichos valores mediante regresiones lineales y no lineales. Los compuestos evaluados contra R. solani AG-3 fueron: alil isotiocianato (AITC), bencil isotiocianato (BITC), fenil isotiocianato (PITC), fenetil isotiocianato (PEITC) y metil isotiocianato (MITC). El ensayo se llevó a cabo en el Laboratorio de Biotecnología de la Facultad de Agronomía de la Universidad Nacional de Colombia, sede Bogotá. Manteniendo agitación constante, se prepararon diluciones de los ITC utilizando metanol como solvente, para obtener las concentraciones 0,0; 0,01; 0,1; 1,0 y 10,0%, que correspondieron a los distintos tratamientos evaluados. En cada uno de ellos se agregaron 50 mL de una de estas soluciones a las unidades experimentales, consistentes en cajas de petri con medio PDA y micelio de R. solani AG-3, selladas herméticamente y almacenadas a temperatura ambiente. Pasadas 72 y 144 horas después de la aplicación de los tratamientos (hdt), se tomaron fotografías digitales para calcular el área de crecimiento micelial con el software MapMaker® 3.5. Esto permitió obtener la Concentración Efectiva Media (CE50) y la Concentración Efectiva 95 (CE95) mediante regresiones lineales, no lineales (modelos Gompertz, logístico y polinómico) y análisis Probit. Los valores obtenidos a partir de este último distan bastante de lo observado, que a su vez coincide con los valores encontrados por regresión lineal. A la concentración del 10%, todos los ITC, excepto PEITC, mostraron un efecto inhibitorio total. Por su parte, BITC mantuvo su efecto fungistático hasta 21 días después de aplicados los tratamientos, mientras que PITC, AITC y MITC mantuvieron un efecto fungistático más prolongado, inclusive hasta un año después de iniciados los tratamientos. Abstract in english Framed in the evaluation of the effect of some isothiocyanates (ITC) on the growth of Rhizoctonia solani Kühn, the present research also studied whether the applied statistical method determines significant differences in the values of the Median (EC50) and 95 (EC95) effective concentrations of thes [...] e compounds. For this purpose, we conducted an in vitro experiment in which said values were calculated by different statistical methods. In vitro efficacy against R. solani AG-3 was tested of allyl isothiocyanate (AITC), benzyl isothiocyanate (BITC), phenyl isothiocyanate (PITC), phenethyl isothiocyanate (PEITC) and methyl isothiocyanate (MITC). Under constant shaking we prepared stock solutions by mixing ITC with methanol as solvent, to get concentrations of 0.0, 0.01, 0.1, 1.0, and 10%, corresponding to the different studied treatments; each of which consisted in the addition of 50 mL of one of these solutions to the experimental units. The latter were Petri dishes containing potato-dextrose-agar medium (PDA) and mycelium of R. solani AG-3. These containers were then sealed with two layers of parafilm and incubated at room temperature. Digital pictures were taken to obtain the colony areas using MapMaker 3.5® software, 72 and 144 hours after the treatments were applied. The Median (EC50) and 95 (EC95) effective concentrations were calculated through linear and non-linear (Gompertz, logistic, and polynomial models) regressions, as well as probit analysis. The values obtained through the latter were found to be considerably different from the actual ones, which in turn coincided with those found by means of linear regressions. All of ITC at 10% concentration were completely inhibitory, with the exception of PEITC. Whereas BITC was fungistatic up to twenty one days a

Luis Federico, Molina-Vargas; Sandra Esperanza, Melo-Martínez.

2010-08-01

233

Detection of trypsin inhibitor in seeds of Eucalyptus urophylla and its influence on the in vitro growth of the fungi Pisolithus tinctorius and Rhizoctonia solani / Descoberta de inibidor de tripsina em sementes de Eucalyptus urophylla e sua influência sobre o crescimento in vitro dos fungos Pisolithus tinctorius e Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: English Abstract in portuguese Os inibidores de proteases de plantas podem regular a hidrólise de proteínas no interior celular e também participar de seus mecanismos de defesa contra insetos herbívoros e patógenos. No presente trabalho, nós demonstramos que sementes de Eucalyptus urophylla apresentam atividades de inibidores de [...] tripsina e papaína, duas proteases comumente encontradas em seres vivos. Pequenas quantidades de proteínas do extrato protéico bruto de sementes e de frações parcialmente purificadas por filtração em gel, com atividade inibitória de tripsina, inibiram o crescimento micelial in vitro de um isolado compatível do fungo ectomicorrízico Pisolithus tinctorius e permitiram um crescimento insatisfatório de outro isolado de Pinus taeda, considerado compatível para esta espécie de eucalipto. As mesmas concentrações de proteínas, quando testadas in vitro sobre o patógeno Rhizoctonia solani, não demonstraram qualquer efeito sobre seu crescimento. Estes resultados indicam a existência de inibidores de proteases em sementes de E. urophylla, os quais poderiam influenciar o complexo sistema bioquímico que diferencia mecanismos de simbiose e patogenicidade entre plantas e microrganismos. Abstract in english Inhibitors of plant proteases can regulate the hydrolysis of proteins inside the cells and also participate in the mechanisms of plant defense against herbivore insects and pathogens. Here, we demonstrated that seeds of Eucalyptus urophylla exhibit activities of trypsin and papain inhibitors, two pr [...] oteases commonly found in living cells. Low amounts of proteins of the crude protein extract of seeds and fractions partially purified by gel filtration, with inhibitory activity against trypsin, inhibited in vitro the mycelial growth of a compatible isolate of the ectomycorrhizal fungus Pisolithus tinctorius and allowed an unsatisfactory growth of another isolate from Pinus taeda, considered incompatible for this eucalyptus species. The same amounts of inhibitory proteins, when tested in vitro on the pathogen Rhizoctonia solani, did not exhibit any effect on the growth of the pathogen. These results indicate the existence of proteases inhibitors in seeds of E. urophylla which could influence the complex biochemical system that differentiates mechanisms of symbiosis and pathogenicity between plants and microorganisms.

Célia Regina, Tremacoldi; Sérgio Florentino, Pascholati.

234

Evaluación in vitro de aislamientos de Trichoderma harzianum para el control de Rhizoctonia solani, Sclerotium rolfsii y Fusarium oxysporum en plantas de tomate / In vitro evaluation of Trichoderma harzianum for control of Rhizoctonia solani, Sclerotium rolfsii, and Fusarium oxysporum in tomato plants  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish En este estudio se determinó la capacidad antagónica de aislamientos de T. harzianum para el control de Rhizoctonia solani, Sclerotium rolfsii y Fusarium oxysporum en raíces de plantas de tomate. Se obtuvieron 6 aislamientos de T. harzianum de 6 municipios del estado Trujillo, empleando la técnica d [...] e siembra directa de raíces en agar agua acidificada. El antagonismo se realizó en cultivos duales utilizando agar papa dextrosa, incubados a 25 ºC, bajo un diseño al azar, con 18 tratamientos conformados por cada aislamiento de T. harzianum y cada patógeno, 3 tratamientos testigos correspondientes a cada patógeno y 3 repeticiones por tratamiento, evaluándose el modo de acción e inhibición del crecimiento radial al tercer día. Todos los aislamientos de T. harzianum mostraron un rápido crecimiento sin diferencias significativas entre ellos (p>0,05), aún cuando se observó que el T121 fue más eficaz como controlador. Al comparar el crecimiento de los aislamientos de T. harzianum con el de los hongos patógenos, se obtuvieron diferencias significativas (p Abstract in english This study determined the antagonistic capacity of T. harzianum isolates for control of Rhizoctonia solani, Sclerotium rolfsii, and Fusarium oxysporum in the roots of tomato plants. Six T. harzianum isolates were obtained from 6 municipalities of Trujillo State, using the direct inoculation of roots [...] in acidified water agar technique. The antagonism was carried out in dual cultures using potato dextrose agar, incubated at 25 ºC, under a random design, with 18 treatments conformed for each T. harzianum isolate and each pathogen, 3 control treatments corresponding to each pathogen, and 3 repetitions per treatment, evaluating the mode of action and inhibition of radial growth at the third day. All the T. harzianum isolates showed rapid growth without significant differences among them (p>0.05), even though it was observed that T121 was more efficient as controller. When comparing the growth of the T. harzianum isolates with that of the pathogenic fungi, there were significant differences (p

Clemencia, Guédez; Luis, Cañizalez; Carmen, Castillo; Rafael, Olivar.

2012-06-01

235

Identificación y caracterización de seis aislados pertenecientes al género Bacillus promisorios para el control de Rhizoctonia solani Künh y Sclerotium rolfsii Sacc. / Identification and Characterization of Six Isolates from Genera Bacillus with Antagonistic Capacity against Rhizoctonia solani Künh and Sclerotium rolfsii Sacc. Control  

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Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish En la actualidad la identificación de los microorganismos se realiza por varios métodos. Existen métodos clásicos que utilizan como criterios de diferenciación los caracteres fenotípicos morfológicos y fisiológicos. Los kits miniaturizados, como los API 50CHB para Bacillusayudan a caracterizar la fi [...] siología de las bacterias pertenecientes a este grupo, de manera fácil y rápida; además, resultan muy útiles para la identificación hasta el nivel de especie por su elevada precisión. La observación de la morfología y esporulación, la respuesta a la tinción de Gram y algunas pruebas bioquímicas permiten, en el caso de Bacillus spp., ubicarlos dentro de su género. El objetivo de esta investigación fue caracterizar morfológica, bioquímica y fisiológicamente seis aislados de suelo y rizosfera pertenecientes al género Bacillus con capacidad antagónica frente a Rhizoctonia solani y Sclerotium rolfsii (Sr.), con la utilización del API 50 CHB.Tres de los aislados resultaron pertenecer a la especie de Bacillus subtilisy otro a B. megateriumcon más del 95% de confiabilidad, además un aislado de B. licheniformis y otro de B. circulans, ambos con el 82,7%. Abstract in english Microorganism identification is realized by several methods, currently. Classical methods utilize phenotypic, morphologic and physiological characters as differentiation criteria. Commercial miniaturized kits as API 50CHB for Bacillus, helps to characterize physiology of this kind of bacteria in an [...] easy and fast way; furthermore they are useful for identification until species level due to their high precision. Observation of morphology and sporulation, the answer to Gram tinction and some biochemical tests permit, in the case of Bacillus spp., put them within they genera. The objective of this investigation was to characterize morphologic, biochemical and physiologically six isolated of genera Bacillusfrom soil and rhizosphere with antagonistic capability in front of Rhizoctonia solani and Sclerotium rolfsii(Sr.), with the utilization of the API 50 CHB. Three of the isolated proved to belong to species Bacillus subtilis and another one to B. megaterium with over than 95% of reliability, also one isolated of B. licheniformis and another one of B. circulans, both with 82.7%.

Acenet I., Sosa López; Victoria, Pazos Álvarez-Rivera; Dania, Torres Campos; Luis, Casadesús Romero.

2011-03-01

236

Evaluación in vitro de aislamientos de Trichoderma harzianum para el control de Rhizoctonia solani, Sclerotium rolfsii y Fusarium oxysporum en plantas de tomate / In vitro evaluation of Trichoderma harzianum for control of Rhizoctonia solani, Sclerotium rolfsii, and Fusarium oxysporum in tomato plants  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish En este estudio se determinó la capacidad antagónica de aislamientos de T. harzianum para el control de Rhizoctonia solani, Sclerotium rolfsii y Fusarium oxysporum en raíces de plantas de tomate. Se obtuvieron 6 aislamientos de T. harzianum de 6 municipios del estado Trujillo, empleando la técnica d [...] e siembra directa de raíces en agar agua acidificada. El antagonismo se realizó en cultivos duales utilizando agar papa dextrosa, incubados a 25 ºC, bajo un diseño al azar, con 18 tratamientos conformados por cada aislamiento de T. harzianum y cada patógeno, 3 tratamientos testigos correspondientes a cada patógeno y 3 repeticiones por tratamiento, evaluándose el modo de acción e inhibición del crecimiento radial al tercer día. Todos los aislamientos de T. harzianum mostraron un rápido crecimiento sin diferencias significativas entre ellos (p>0,05), aún cuando se observó que el T121 fue más eficaz como controlador. Al comparar el crecimiento de los aislamientos de T. harzianum con el de los hongos patógenos, se obtuvieron diferencias significativas (p Abstract in english This study determined the antagonistic capacity of T. harzianum isolates for control of Rhizoctonia solani, Sclerotium rolfsii, and Fusarium oxysporum in the roots of tomato plants. Six T. harzianum isolates were obtained from 6 municipalities of Trujillo State, using the direct inoculation of roots [...] in acidified water agar technique. The antagonism was carried out in dual cultures using potato dextrose agar, incubated at 25 ºC, under a random design, with 18 treatments conformed for each T. harzianum isolate and each pathogen, 3 control treatments corresponding to each pathogen, and 3 repetitions per treatment, evaluating the mode of action and inhibition of radial growth at the third day. All the T. harzianum isolates showed rapid growth without significant differences among them (p>0.05), even though it was observed that T121 was more efficient as controller. When comparing the growth of the T. harzianum isolates with that of the pathogenic fungi, there were significant differences (p

Clemencia, Guédez; Luis, Cañizalez; Carmen, Castillo; Rafael, Olivar.

237

Identificación y caracterización de seis aislados pertenecientes al género Bacillus promisorios para el control de Rhizoctonia solani Künh y Sclerotium rolfsii Sacc. / Identification and Characterization of Six Isolates from Genera Bacillus with Antagonistic Capacity against Rhizoctonia solani Künh and Sclerotium rolfsii Sacc. Control  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish En la actualidad la identificación de los microorganismos se realiza por varios métodos. Existen métodos clásicos que utilizan como criterios de diferenciación los caracteres fenotípicos morfológicos y fisiológicos. Los kits miniaturizados, como los API 50CHB para Bacillusayudan a caracterizar la fi [...] siología de las bacterias pertenecientes a este grupo, de manera fácil y rápida; además, resultan muy útiles para la identificación hasta el nivel de especie por su elevada precisión. La observación de la morfología y esporulación, la respuesta a la tinción de Gram y algunas pruebas bioquímicas permiten, en el caso de Bacillus spp., ubicarlos dentro de su género. El objetivo de esta investigación fue caracterizar morfológica, bioquímica y fisiológicamente seis aislados de suelo y rizosfera pertenecientes al género Bacillus con capacidad antagónica frente a Rhizoctonia solani y Sclerotium rolfsii (Sr.), con la utilización del API 50 CHB.Tres de los aislados resultaron pertenecer a la especie de Bacillus subtilisy otro a B. megateriumcon más del 95% de confiabilidad, además un aislado de B. licheniformis y otro de B. circulans, ambos con el 82,7%. Abstract in english Microorganism identification is realized by several methods, currently. Classical methods utilize phenotypic, morphologic and physiological characters as differentiation criteria. Commercial miniaturized kits as API 50CHB for Bacillus, helps to characterize physiology of this kind of bacteria in an [...] easy and fast way; furthermore they are useful for identification until species level due to their high precision. Observation of morphology and sporulation, the answer to Gram tinction and some biochemical tests permit, in the case of Bacillus spp., put them within they genera. The objective of this investigation was to characterize morphologic, biochemical and physiologically six isolated of genera Bacillusfrom soil and rhizosphere with antagonistic capability in front of Rhizoctonia solani and Sclerotium rolfsii(Sr.), with the utilization of the API 50 CHB. Three of the isolated proved to belong to species Bacillus subtilis and another one to B. megaterium with over than 95% of reliability, also one isolated of B. licheniformis and another one of B. circulans, both with 82.7%.

Acenet I., Sosa López; Victoria, Pazos Álvarez-Rivera; Dania, Torres Campos; Luis, Casadesús Romero.

238

Efecto inhibitorio in vitro de cinco monoterpenos de aceites esenciales sobre un aislado de Rhizoctonia solani en papa (Solanum tuberosum L.) / Inhibitory Effect in vitro of Five Monoterpens from Essentials Oils on a Rhizoctonia solani Isolate in Potato (Solanum tuberosum L.)  

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Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish En los últimos años la sociedad mundial ha priorizado los aspectos ambientales, y ha conducido un grupo de investigaciones hacia el descubrimiento de nuevas alternativas para el manejo integrado de plagas y enfermedades, con menos efectos negativos al ambiente. Los aceites esenciales, que hasta hace [...] poco eran empleados solamente en la industria farmacéutica y cosmética, en la actualidad tienen gran importancia por su efecto en el control de plagas y enfermedades de las plantas. Basado en este criterio, se evaluó la actividad fungicida de cinco monoterpenos (mentol, timol, alcanfor, citronelal y 1,8 cineol) comúnmente encontrados en aceites esenciales. Se empleó el método de envenenamiento del medio de cultivo a concentraciones de 0,5; 0,1 y el 0,05% p/v para evaluar el efecto inhibitorio de cada uno sobre un aislado de Rhizoctonia solani, causante de la rizoctoniasis en papa. Se calculó el porcentaje de inhibición y los resultados se analizaron estadísticamente. Se obtuvo que timol, mentol y citronelal tuvieron el 100% de inhibición al 0,1 y el 0,5%; Por otra parte, alcanfor y 1,8 cineol mostraron resultados por debajo del 100%; pero se valorarán para posteriores estudios, donde el rango de concentración sea mayor. Abstract in english The looking for new alternative to chemical control for integrated pest management to reduce the environmental impact has received attention internationally in last decades. Essentials oils have been using in pharmaceutical and cosmetic industry, recently they have become in an interesting possibili [...] ty for pest and disease control. The fungicide activity of five monoterpens (menthol, thymol, camphor, citronellal and 1,8 cineol), commonly found in essentials oils was evaluated. The method of culture media poisoning was used with concentration of 0,5; 0,1 y 0,05% w/v. The inhibitory effect was evaluated on a Rhizoctonia solani isolate, pathogen which causes rizoctoniasis in potato crops. The inhibition percentage was calculated and the results were statistically analyzed. Thymol, menthol and citronellal showed 100% of inhibition at 0,5 and 0,1%. The monoterpens camphor and 1, 8 cineol showed lower values of inhibition percentage, but they will taking into account for future studies with a wider range of concentration.

Daymara, Vaillant Flores; Carlos, Romeu Carballo; Elda, Ramos Ramos; Marleny, González García; Rebeca, Ramírez Ochoa; Johan, González Pentón.

239

Research on possibilities of utilization of chosen Brassicaceae plants in protection of cucumber against damping-off caused by Rhizoctonia solani Kühn and Fusarium culmorum (W.G.SmithSacc.  

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Full Text Available The aim of the work was to determine the usefulness of dried leaves of savoy cabbage, red cabbage, horse radish and fringed cabbage in protection of cucumber against damping-off caused by fungi Rhizoctonia solani and Fusarium culmorum. In the laboratory experiments, pathogens were grown on PDA containing dried leaves (3g·100 cm-3 and in atmosphere containing volatile substances evolved from plant material. The addition of radish horse leaves into PDA caused total inhibition of R. solani development. Remaining plants were also characterized by high fungistatic activity (% of growth inhibition about 85%. F. culmorum was less sensitive. The horse radish leaves showed the strongest activity (65 %, weakest in combination with fringed cabbage leaves (38,9%. The similar regularity in the case of fumigation activity was observed. The effectiveness of dried leaves in protection of cucumber against damping-off was confirmed in greenhouse experiment. The amendment of soil inoculated with R. solani in dose 2 g per 500 cm3 of soil significantly increased the number of cucumber sprouts compared to the control. In the experiment with F. culmorum only in combination with horse radish and red cabbage leaves significant action was observed.

Zbigniew J. Burgie?

2005-12-01

240

Efeito do tratamento de sementes de algodoeiro com fungicidas no controle do tombamento de plântulas causado por Rhizoctonia solani, sob condições de casa de vegetação / of cotton seed treatment with fungicides in the control of Rhizoctonia solani seedling damping-off under greenhouse conditions  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi avaliar a eficácia do tratamento de sementes de algodoeiro com fungicidas no controle do tombamento de plântulas causado por Rhizoctonia solani. O ensaio foi conduzido na casa de vegetação da Embrapa Agropecuária Oeste, em Dourados, Mato Grosso do Sul. Sementes não trat [...] adas e tratadas com os fungicidas foram semeadas em areia contida em bandejas plásticas, dispostas em orifícios individuais, eqüidistantes e a 3 cm de profundidade. A inoculação com R. solani AG-4 foi feita utilizando-se 5g do inóculo do fungo/bandeja, distribuídos de forma homogênea na superfície do substrato. O fungo foi cultivado por 35 dias em sementes de aveia preta autoclavadas e trituradas em moinho (1mm). Foi observado efeito significativo do tratamento fungicida na emergência inicial e final de plântulas, bem como no controle do tombamento de pré e pós-emergência do algodoeiro, com os melhores resultados sendo obtidos pelos tratamentos tolylfluanid+pencycuron+triadimenol e azoxystrobin+fludioxonil+mefenoxan, seguidos de carboxin+thiram, PCNB e pencycuron. O fungicida menos eficiente foi o carbendazim+thiram. Melhores resultados com relação às variáveis estudadas foram obtidos com a utilização de misturas de fungicidas em comparação ao uso isolado de um determinado produto. Não foram observadas diferenças significativas com relação ao índice de velocidade de emergência, altura e peso fresco das plântulas. Abstract in english The objective of this work was to evaluate the efficacy of cotton seed treatment with fungicides in the control of R. solani seedling damping-off. This experiment was carried out under greenhouse conditions at Embrapa Agropecuária Oeste, in Dourados city, Mato Grosso do Sul State, Brazil. Treated an [...] d untreated seeds of the cultivar DeltaOpal were sowed in sand contained in plastic trays, placed in individual and equidistant wells, 3cm deep. Into each plastic tray were put 5g of the pathogen inoculum. The inoculation of R. solani AG-4 was done by the homogeneous distribution of the fungus inoculum onto the substrate. The fungus was grown for 35 days on autoclaved oat seeds and then ground to powder using a mill (1mm). The evaluations were done based on symptoms development and seedling survival. The significant effect of the fungicide treatment on initial and final seedling emergence, as well as in the control of pre and post-emergence damping-off was observed. The best results were obtained with tolylfluanid+pencycuron+triadimenol and azoxystrobin+fludioxonil+mefenoxan, followed by carboxin+thiram, PCNB and pencycuron. The least efficient fungicide was carbendazim+thiram. Seed treatment with fungicide combinations provided better results than the use of the single ones. No significant effect was observed in relation to speed of emergence index, seedling height and seedling fresh weight.

Augusto César Pereira, Goulart.

 
 
 
 
241

Efeito do tratamento de sementes de algodoeiro com fungicidas no controle do tombamento de plântulas causado por Rhizoctonia solani, sob condições de casa de vegetação of cotton seed treatment with fungicides in the control of Rhizoctonia solani seedling damping-off under greenhouse conditions  

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Full Text Available O objetivo deste trabalho foi avaliar a eficácia do tratamento de sementes de algodoeiro com fungicidas no controle do tombamento de plântulas causado por Rhizoctonia solani. O ensaio foi conduzido na casa de vegetação da Embrapa Agropecuária Oeste, em Dourados, Mato Grosso do Sul. Sementes não tratadas e tratadas com os fungicidas foram semeadas em areia contida em bandejas plásticas, dispostas em orifícios individuais, eqüidistantes e a 3 cm de profundidade. A inoculação com R. solani AG-4 foi feita utilizando-se 5g do inóculo do fungo/bandeja, distribuídos de forma homogênea na superfície do substrato. O fungo foi cultivado por 35 dias em sementes de aveia preta autoclavadas e trituradas em moinho (1mm. Foi observado efeito significativo do tratamento fungicida na emergência inicial e final de plântulas, bem como no controle do tombamento de pré e pós-emergência do algodoeiro, com os melhores resultados sendo obtidos pelos tratamentos tolylfluanid+pencycuron+triadimenol e azoxystrobin+fludioxonil+mefenoxan, seguidos de carboxin+thiram, PCNB e pencycuron. O fungicida menos eficiente foi o carbendazim+thiram. Melhores resultados com relação às variáveis estudadas foram obtidos com a utilização de misturas de fungicidas em comparação ao uso isolado de um determinado produto. Não foram observadas diferenças significativas com relação ao índice de velocidade de emergência, altura e peso fresco das plântulas.The objective of this work was to evaluate the efficacy of cotton seed treatment with fungicides in the control of R. solani seedling damping-off. This experiment was carried out under greenhouse conditions at Embrapa Agropecuária Oeste, in Dourados city, Mato Grosso do Sul State, Brazil. Treated and untreated seeds of the cultivar DeltaOpal were sowed in sand contained in plastic trays, placed in individual and equidistant wells, 3cm deep. Into each plastic tray were put 5g of the pathogen inoculum. The inoculation of R. solani AG-4 was done by the homogeneous distribution of the fungus inoculum onto the substrate. The fungus was grown for 35 days on autoclaved oat seeds and then ground to powder using a mill (1mm. The evaluations were done based on symptoms development and seedling survival. The significant effect of the fungicide treatment on initial and final seedling emergence, as well as in the control of pre and post-emergence damping-off was observed. The best results were obtained with tolylfluanid+pencycuron+triadimenol and azoxystrobin+fludioxonil+mefenoxan, followed by carboxin+thiram, PCNB and pencycuron. The least efficient fungicide was carbendazim+thiram. Seed treatment with fungicide combinations provided better results than the use of the single ones. No significant effect was observed in relation to speed of emergence index, seedling height and seedling fresh weight.

Augusto César Pereira Goulart

2008-10-01

242

Efeito do tratamento de sementes de algodoeiro com fungicidas no controledo tombamento em relação à densidade de inóculo de Rhizoctonia solani / Effect of cotton seed treatments with fungicides to control damping-off in relation to inoculum densities of Rhizoctonia solani  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O fungo Rhizoctonia solani Kuhn é considerado o principal agente causal do tombamento de plântulas do algodoeiro no Brasil. A maneira mais eficiente e econômica de controlar essa doença é através do tratamento das sementes com fungicidas. A performance dos fungicidas depende, dentre outros fatores, [...] da população desse fungo no solo. Este trabalho foi desenvolvido, em condições de casa de vegetação, na Embrapa Agropecuária Oeste, em Dourados, MS, com o objetivo de determinar o efeito do tratamento de sementes de algodoeiro com fungicidas, no controle do tombamento, em relação a diferentes densidades de inóculo de R. solani no solo. Sementes da cultivar DeltaOpal, tratadas e não tratadas com diferentes fungicidas, foram semeadas a 3 cm de profundidade em areia contida em bandejas plásticas. As sementes foram dispostas em orifícios individuais e eqüidistantes. A inoculação com o fungo foi feita pela distribuição homogênea do inóculo na superfície do substrato. O fungo foi cultivado por 35 dias em sementes de aveia preta autoclavadas e trituradas em moinho (1 mm). Quatro densidades de inóculo foram testadas: 1 g; 2 g; 3 g e 4 g/bandeja plástica de 56x35x10 cm. Foi observado efeito do tratamento fungicida na emergência inicial e final de plântulas, bem como no controle do tombamento de pré e pós-emergência. O tratamento das sementes com a mistura de fungicidas proporcionou os melhores resultados no controle do tombamento em comparação ao seu uso isolado. A interação fungicidas x densidade de inóculo foi significativa, indicando que a eficiência dos fungicidas foi influenciada pela densidade de inóculo do fungo. A performance dos fungicidas testados foi melhor na presença dos níveis mais baixos de inóculo do fungo (1,0 g e 2,0 g/bandeja). A eficiência dos fungicidas testados foi menor para as populações de 3,0g e 4,0g do patógeno, sendo que a maioria dos tratamentos fungicidas apresentou perda significativa de eficiência na presença desses níveis de R. solani. Os fungicidas usados neste estudo não apresentaram efeitos fitotóxicos às plântulas de algodoeiro. Abstract in english The fungus Rhizoctonia solani Kuhn is considered the most important cause of cotton damping-off in Brazil. Treatment of seeds with fungicides is the most efficient and economical procedure to control this disease. The performance of fungicides depends, among many other factors, of the pathogen popul [...] ation in the soil. This work was carried out, under greenhouse conditions at Embrapa Agropecuária Oeste, Dourados, MS, with the goal to determine the effect of treatment of cotton seeds with fungicides to control damping-off at different inoculum densities of R. solani in the soil. Seeds of cultivar DeltaOpal treated or not with different fungicides were sowed 3 cm deep in sand contained in plastic flats. Seeds were placed in individual and equidistant wells. Inoculum of the fungus was homogeneously distributed in the substrate. The fungus was grown for 35 days on autoclaved oat seeds and then ground to powder using a mill until reach the size of 1mm. Four inoculum densities were tested: 1 g; 2 g; 3 g e 4 g/plastic flat with dimensions of 56x35x10 cm. The effect of the fungicide treatment on initial and final seedling emergence, as well as, in the control of post and pre-emergence damping-off was observed. Treatment of seed with a combinations of fungicides gave the best results in controlling damping-off as compared to the use of each fungicide alone. The interaction fungicides x inoculum densities, was significant indicating that the efficiency of the fungicides was somehow affected by the fungus densities. Fungicides had the best performance at low inoculum densities (1g and 2g/flat). As for fungi populations of 3g and 4g/flat, the efficiency of all fungicides tested decreased sharply, with a reduced control of the disease. The fungicides used in this study did not have any phytotoxic effect on cotton seedlings.

Augusto César Pereira, Goulart.

243

Evaluación de un biofungicida para el control de la mancha bandeada del maíz causada por Rhizoctonia Solani Kühn en siembras comerciales en Portuguesa, Venezuela / Evaluation of a biofungicide for the control of maize banded stripe Rhizoctonia Solani Kühn on commercial fields at the Portuguesa state, Venezuela  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish El objetivo principal de este trabajo fue evaluar el efecto de un biofungicida, a base de Trichoderma harzianum, sobre la incidencia y la severidad de la enfermedad mancha bandeada del maíz causada por el hongo Rhizoctonia solani Kühn, anamorfo de Thanathephorus cucumeris, en parcelas comerciales en [...] el estado Portuguesa, Venezuela, durante el ciclo de lluvias de 2001. Se seleccionaron parcelas en 8 localidades donde se presentaba la enfermedad en forma endémica. Las mismas fueron subdivididas en 2 lotes de aproximadamente 5 ha c/u; uno se trató con el biofungicida y el otro se dejó sin tratar. La aplicación se hizo en 2 fases: tratando la semilla con 100 g del biofungicida /20 kg de semilla y una segunda aplicación a los 30 días después de la siembra usando 3,0 l del producto comercial /ha. En cada parcela la siembra de los lotes tratados y no tratados se realizó de manera simultánea. La incidencia y la severidad de la enfermedad se determinaron a los 70 días después de la emergencia, seleccionando 5 puntos de muestreo distri­buidos uniformemente en cada lote. La incidencia fue determinada utilizando un arreglo factorial en un diseño de bloques al azar con 5 repeticiones y la severidad por vía no paramétrica mediante la prueba de Friedman. En promedio, el biofungicida disminuyó cerca de 50% la incidencia de la enfermedad en todas las localidades. Los resultados mostraron el efecto benéfico del biofungicida, representando una alternativa viable, eficaz y amigable con el ambiente para el control de la enfermedad. Abstract in english The objective of this study was to determine the effect of a biofungicide, Trichoderma harzianum, on the incidence and severity of the disease maize banded leaf caused by Rhizoctonia solani Kühn fungus, anamorph of Thanathephorus cucumeris, in commercial fields of corn, at the Portuguesa State, Vene [...] zuela, during the rainy season of the 2001 year. We selected commercial plots in eight locations normally affected by the disease. In each place the plots were divided in two areas, each one of about 5 ha; in each place one of the 5 ha was treated with the biofungicide, and the other one was allowed without any application. The biofungicide dose was split: at the sowing time in the seed (100 g of biofungicide /20 kg of seed), and 30 days after sowing in a dose of 3 liters of the commercial product /ha. Treated and no treated plots were sowed at the same time. We evaluated the incidence and severity of the fungus at about 70 days of the crop cycle, in 5 areas inside each plot. The incidence was analyzed using a factorial arrangement in a randomized block design with 5 replications, while the severity was analyzed using the Friedman non-parametric test. We found that the biofungicide reduced the disease in 50% in all locations. This result showed the beneficial effects of the biofungicide, and it represent a valuable, successful and environmental friendly alternative to control the disease.

Pedro J, García M; Samuel R, Cabrera P; Jimmy J, Sánchez; Alberto A, Pérez C.

244

Evaluación de un biofungicida para el control de la mancha bandeada del maíz causada por Rhizoctonia Solani Kühn en siembras comerciales en Portuguesa, Venezuela / Evaluation of a biofungicide for the control of maize banded stripe Rhizoctonia Solani Kühn on commercial fields at the Portuguesa state, Venezuela  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish El objetivo principal de este trabajo fue evaluar el efecto de un biofungicida, a base de Trichoderma harzianum, sobre la incidencia y la severidad de la enfermedad mancha bandeada del maíz causada por el hongo Rhizoctonia solani Kühn, anamorfo de Thanathephorus cucumeris, en parcelas comerciales en [...] el estado Portuguesa, Venezuela, durante el ciclo de lluvias de 2001. Se seleccionaron parcelas en 8 localidades donde se presentaba la enfermedad en forma endémica. Las mismas fueron subdivididas en 2 lotes de aproximadamente 5 ha c/u; uno se trató con el biofungicida y el otro se dejó sin tratar. La aplicación se hizo en 2 fases: tratando la semilla con 100 g del biofungicida /20 kg de semilla y una segunda aplicación a los 30 días después de la siembra usando 3,0 l del producto comercial /ha. En cada parcela la siembra de los lotes tratados y no tratados se realizó de manera simultánea. La incidencia y la severidad de la enfermedad se determinaron a los 70 días después de la emergencia, seleccionando 5 puntos de muestreo distri­buidos uniformemente en cada lote. La incidencia fue determinada utilizando un arreglo factorial en un diseño de bloques al azar con 5 repeticiones y la severidad por vía no paramétrica mediante la prueba de Friedman. En promedio, el biofungicida disminuyó cerca de 50% la incidencia de la enfermedad en todas las localidades. Los resultados mostraron el efecto benéfico del biofungicida, representando una alternativa viable, eficaz y amigable con el ambiente para el control de la enfermedad. Abstract in english The objective of this study was to determine the effect of a biofungicide, Trichoderma harzianum, on the incidence and severity of the disease maize banded leaf caused by Rhizoctonia solani Kühn fungus, anamorph of Thanathephorus cucumeris, in commercial fields of corn, at the Portuguesa State, Vene [...] zuela, during the rainy season of the 2001 year. We selected commercial plots in eight locations normally affected by the disease. In each place the plots were divided in two areas, each one of about 5 ha; in each place one of the 5 ha was treated with the biofungicide, and the other one was allowed without any application. The biofungicide dose was split: at the sowing time in the seed (100 g of biofungicide /20 kg of seed), and 30 days after sowing in a dose of 3 liters of the commercial product /ha. Treated and no treated plots were sowed at the same time. We evaluated the incidence and severity of the fungus at about 70 days of the crop cycle, in 5 areas inside each plot. The incidence was analyzed using a factorial arrangement in a randomized block design with 5 replications, while the severity was analyzed using the Friedman non-parametric test. We found that the biofungicide reduced the disease in 50% in all locations. This result showed the beneficial effects of the biofungicide, and it represent a valuable, successful and environmental friendly alternative to control the disease.

Pedro J, García M; Samuel R, Cabrera P; Jimmy J, Sánchez; Alberto A, Pérez C.

2008-12-01

245

Evaluation of chitinase activity in biological control process of rhizoctonia solani y fusarium oxysporum f. sp. lycopersici in tomate, by using seed priming in the presence of trichoderma koningii  

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Full Text Available The present work intended to establish in a control model, the possible role of chitinases by using seed priming in the presence of Trichoderma koningii. This method showed to be efficient to control Rhizoctonia solani and Fusarium oxysporum in tomato. The analysis of seed extracts and exudates, and soil extracts from soil seeded with seeds primed in the presence of T. koningii showed high endochitinase activity in the samples. This activity was higher than that exhibited by samples from primed seeds without antagonist and unprimed seeds.   In vitro evaluation of the hydrolytic activity of the extracts and exudates were performed using F. oxysporum and R. solani cell walls. The results also showed that the samples from seeds primed in the presence of T. koningii exhibited higher endochitinase activity than the others. These data allowed us to conclude that seed priming in the presence of T. koningii promotes endochinolytic activity in seeds. It was also concluded that this chitinase activity is related with the protection previously observed.

A. Clavijo

2012-05-01

246

The Use of Antioxidants and Microelements for Controlling Damping-Off Caused by Rhizoctonia solani and Charcoal Rot Caused by Macrophomina phasoliana on Sunflower  

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Full Text Available Seed soaking method or foliar spray of antioxidants (citric acid and salicylic acid at 10 mM and microelements (manganese and zinc at 2 g L-1 were tested to control of the damping-off and charcoal rot diseases of sunflower (varieties Sakha 53 and Giza 102. Field treatments in two different localities i.e., Tag El-Ezz, Dakahlia province and El-Serow, Damietta province were carried out. The high frequency isolated fungi (M. phaseolina and R. solani presented in Tag El-Ezz location. On the other hand, M. phaseolina was isolated at a high frequency compared with R. solani in both locations. Sakha 53 was highly susceptible compered with Giza 102 when artificially infected with both M. phaseolina and R. solani. Laboratory results showed that salicylic acid alone or in combination with citric acid completely inhibited the linear growth of both pathogens i.e., M. phasoliana and R. solani in vitro. A positive correlation between the concentrations of Rizolex-T 50 and its effect on the fungal growth were recorded. The dose of 3 g L-1 prevented the growth of R. solani linear growth in vitro. The greenhouse results revealed that Giza 102 variety was highly susceptible to the infection by R. solani. M. phasoliana showed severe symptoms in both sunflower varieties. On contrary, Giza 102 variety was tolerant to damping-off and charcoal rot diseases than Sakha 53 under field conditions. The application of Rizolex-T 50 followed by citric acid showed a highest percentage of healthy plants followed by the combination of citric acid and salicylic acid. The application of manganese combined with zinc was more effective than the microelements alone. All treatments of antioxidants and microelements significantly reduced the incidence of charcoal rot disease. On the other hand, no significant differences between Rizolex-T 50 and salicylic acid treatments was shown. Sakha 53 variety gave the highest values of plant height and number of leaves plant-1 while Giza 102 recorded the highest values of stem diameter and flower head diameter. The application of citric acid combined with salicylic acid maximized the plant height followed by the mixture of manganese and zinc. Manganese treatment followed by the mixture of citric acid and salicylic acid then zinc were the most effective in increasing the number of leaves plant-1. While, Rizolex-T 50 had no significant effect on plant height and number of leaves plant-1. Microelements were more effective than antioxidants on enhancing the stem and flower head diameters. The combination between manganese and zinc followed by Rizolex-T 50 recorded the maximum values of the stem and flower head diameters. Giza 102 variety recorded the highest values of 100 seeds weight, total phenols, photosynthetic pigments and the percentage of seed oil when the above applications were carried out. Sakha 53 variety showed the highest plant yield under the above treatment. The mixtures of citric and salicylic acids were highly effective in increasing plant yield. The highest values of photosynthetic pigments were shown in salicylic acid treatment followed by Rizolex-T 50. Total phenols content was highest due to Rizolex-T 50 application followed by salicylic acid. Except zinc, seed oil concentration increased significantly in both antioxidants and microelements treatments on oil concentration.

K.M. Abd El-Hai

2009-01-01

247

Biocontrol capacity of wild and mutant Trichoderma harzianum (Rifai) strains on Rhizoctonia solani 618: effect of temperature and soil type during storage  

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Full Text Available SciELO Chile | Language: English Abstract in english Wild (Th11, Th12 and Th650) and mutant (Th11A80.1, Th12A40.1, Th12C40.1 and Th650-NG7) Trichoderma harzianum strains were stored for 180 days at 5ºC or at 22ºC, in two types of soils. Strains recovered at 90, 120 and 180 days from the two types of soils, retained their full capacity to biocontrol Rh [...] izoctonia solani 618, that produces crown and root rot of tomatoes. Recovery, estimated as colony forming units (cfu) of the wild and mutant strains, showed that all increased their cfu after storage independently of the type of soil and temperature, although kinetic behavior differed among strains. Ratios of recovery after storage in type B soil/ type A soil or at 22ºC/5ºC, higher or lower than one respectively, allowed to establish that Th11 and Th12 were the most appropriate strains for the biocontrol of R. solani in conditions where growth of the phytopathogen is optimal.

Jaime, Montealegre; Luis, Valderrama; Rodrigo, Herrera; Ximena, Besoaín; Luz M, Pérez.

2009-10-15

248

Determination of Culture Condition for Polygalacturonase Production by Rhizoctonia solani AG2-2, Causal Agent of Root Rot in Sugar Beet  

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Full Text Available The objective of the current research was to determine the significant parameters on the production of PG in a submerged culture of R. solani AG2-2 to study PGIP-PG interaction. Taguchi method was applied to evaluate the significant parameters for PG production. The process variables were pH (4, 4.5, 5 and 5.5, pectin as carbon source and inducer (7.5, 10, 12.5 and 15 g L-1 and incubation time (2, 4, 6 and 8 days. The liquid medium also included mineral salts as in Pectic Zymogram (PZ medium. Polygalacturonase activity was determined spectrophotometrically at 500 nm and productivity was calculated at the time of maximal extracellular enzyme activity. Pectin concentration was the most important factor in the enzyme production (34.8% contribution, whereas pH had a minimal contribution (16.9%. The optimal levels of the different factors for PG production were 12.5 g L-1 pectin, pH 4.5 and 6 days of incubation time at 26°C. A maximal productivity of 115.5 U mL-1 was reached in these conditions.

F. Karimzadeh

2007-01-01

249

Differentiation of Rhizoctonia spp. Based on their antigenic properties  

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Full Text Available Antigenic properties and serological relationship was investigated in binucleate and multinucleate Rhizoctonia spp. isolates from strawberries soybean, alfalfa and potato plants from Serbia, from Spain, anastomosis group testers and in strawberry roots inoculated with binucleate Rhizoctonia AG A and AG I. Two polyclonal antisera, unabsorbed and cross absorbed, were used in dot-immunobinding assay for these investigations. Antisera were produced against mycelial antigens of two isolates, which belong to different anastomosis groups (AG of binucleate Rhizoctonia - AG A and AG I. Both unabsorbed antisera reacted positively with all tested Rhizoctonia spp. isolates, and the reaction was absent with control isolates (Pythium sp. Agaricus sp. and Fusarium sp. The results prove a close serological relationship among Rhizoctonia spp. isolates, and diversity between Rhizoctonia spp. and isolates from different taxonomic groups. Also, both unabsorbed antisera reacted with higher intensity with closely related antigens (belonging to the same AG than with ones from another AG of binucleate Rhizoctonia or R. solani (multinucleate Rhizoctonia. After cross absorption specificity of the antisera was enhanced, especially with the antiserum raised against mycelial proteins of binucleate Rhizoctonia AG I. This antiserum reacted positively only with antigens from the same AG, after cross absorption with antigens from AG A of binucleate Rhizoctonia and from R. solani AG 2-2. It proved to be specific to AG I of binucleate Rhizoctonia, and able to differentiate isolates of this AG from others. In this way the serological homology among isolates of one AG was proven, and also the diversity among isolates which belong to different AGs of binucleate Rhizoctonia as well as isolates of R. solani.

Vico Ivana M.

2002-01-01

250

A New Disease of Gladiolus Caused by Binucleate Rhizoctonia sp.  

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Full Text Available Fungi with Rhizoctonia-like mycelia were isolated from root and stem of Gladiolus (Gladiolus hybrida L. grown in commercial glasshouse in Mahallat, Iran, during the summer and fall of 2003. Isolated fungi were identified as either binucleate or multi nucleate Rhizoctonia sp. On the basis of hyphal characteristics and nuclear number, twenty three isolates of Rhizoctonia sp. were obtained from infected corms and stems. Of the 23 isolate, 9 had binucleate and 14 had multinucleate vegetative hyphal cells. Representative isolates of binucleate Rhizoctonia sp. were characterized for anastomosis, optimum temperature in vitro and virulence on Gladiolus. Isolates of binucleate Rhizoctonia failed to anastomose with tester isolates of Anastomosis Groups (AG-A throug-S (not including AG-J and AG-M. The optimum temperature range for growth rate of binucleate Rhizoctonia sp. was 24-28?C. Growth rate of binucleate Rhizoctonia sp. was more rapid than R. solani. Five isolates from each group caused severe corm rot and mortality of plant during rooting. Isolates of binucleate Rhizoctonia caused corm and stem rot and mortality only on 35-day-old plants. This is the first detailed report of corm and stem rot disease of Gladiolus caused by binucleate Rhizoctonia. Further field studies are needed on the ecology and pathogenicity of Rhizoctonia sp. to formulate steps for controlling corm and stem rot of Gladiolus.

Mohammad Javad Soleimani

2005-01-01

251

Análise de proteínas e isoenzimas de isolados de Rhizoctonia spp. patogênicos a Eucalyptus Protein and isozyme analysis of isolates of Rhizoctonia spp. pathogenic to Eucalyptus  

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Full Text Available Objetivou-se caracterizar isolados de Rhizoctonia solani AG1 e AG4 e isolados binucleados de Rhizoctonia spp. patogênicos a Eucalyptus, por meio de eletroforese de proteínas, em gel de poliacrilamida, e de isoenzimas (ACP, 6-PGDH, LAP, SOD, MDH e IDH, em gel de amido. Para comparação, incluíram-se alguns isolados brasileiros de outros hospedeiros e isolados-padrões de R. solani AG1, procedentes do Japão. Observaram-se diferenças nos padrões gerais de proteínas e nos fenótipos isoenzimáticos entre isolados binucleados e multinucleados e entre isolados de diferentes grupos e subgrupos de anastomose. Isolados de R. solani AG1, procedentes do Brasil e Japão, apresentaram baixa similaridade nos padrões de proteínas e de isoenzimas. Isolados brasileiros morfologicamente semelhantes a R. solani AG1-IB (microesclerodiais apresentaram padrões de proteínas similares e um maior número de fenótipos isoenzimáticos idênticos entre si. Esta tendência foi independente do hospedeiro e da origem geográfica. Variações nos padrões de proteínas e de isoenzimas foram também observadas dentre isolados brasileiros de R. solani AG4. Discute-se o uso da eletroforese de proteínas e isoenzimas na caracterização de isolados de Rhizoctonia spp. e em estudos genéticos e filogenéticos de fungos deste gênero.Isolates of Rhizoctonia solani (anastomosis groups AG1 and AG4 and binucleate isolates of other unidentified species, all pathogenic to Eucalyptus in Brazil, were characterized by protein and isozyme (ACP, 6-PGDH, LAP, SOD, MDH e IDH analysis. Japanese strains of R. solani AG1 and other Brazilian isolates from others hosts were also included for comparison. Differences in protein patterns and isozyme phenotypes were observed between binucleate and multinucleate isolates, and among isolates of different anastomosis groups and subgroups. The protein patterns and isozyme phenotypes of Japanese isolates of R. solani AG1 differed from those of Brazilian isolates of the same anastomosis groups and the same morphological subgroups. Some Brazilian isolates morphologically similar to R. solani AG1-IB presented high similarity in protein patterns and isozyme phenotypes. This similarity was independent of the host plant and geographical origin. Polymorphisms in protein and isozyme patterns were also observed within the Brazilian R. solani AG4 group. We discuss the usefulness of protein and isozyme analyses for characterization of Rhizoctonia spp. isolates and for genetic and phylogenetic studies of fungi of this genus.

SILVALDO F. SILVEIRA

2002-02-01

252

Interactions between cauliflower and Rhizoctonia anastomosis groups with different levels of aggressiveness  

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Full Text Available Abstract Background The soil borne fungus Rhizoctonia is one of the most important plant pathogenic fungi, with a wide host range and worldwide distribution. In cauliflower (Brassica oleracea var. botrytis, several anastomosis groups (AGs including both multinucleate R. solani and binucleate Rhizoctonia species have been identified showing different levels of aggressiveness. The infection and colonization process of Rhizoctonia during pathogenic interactions is well described. In contrast, insights into processes during interactions with weak aggressive or non-pathogenic isolates are limited. In this study the interaction of cauliflower with seven R. solani AGs and one binucleate Rhizoctonia AG differing in aggressiveness, was compared. Using microscopic and histopathological techniques, the early steps of the infection process, the colonization process and several host responses were studied. Results For aggressive Rhizoctonia AGs (R. solani AG 1-1B, AG 1-1C, AG 2-1, AG 2-2 IIIb and AG 4 HGII, a higher developmental rate was detected for several steps of the infection process, including directed growth along anticlinal cell walls and formation of T-shaped branches, infection cushion formation and stomatal penetration. Weak or non-aggressive AGs (R. solani AG 5, AG 3 and binucleate Rhizoctonia AG K required more time, notwithstanding all AGs were able to penetrate cauliflower hypocotyls. Histopathological observations indicated that Rhizoctonia AGs provoked differential host responses and pectin degradation. We demonstrated the pronounced deposition of phenolic compounds and callose against weak and non-aggressive AGs which resulted in a delay or complete block of the host colonization. Degradation of pectic compounds was observed for all pathogenic AGs, except for AG 2-2 IIIb. Ranking the AGs based on infection rate, level of induced host responses and pectin degradation revealed a strong correlation with the disease severity caused by the AGs. Conclusion The differences in aggressiveness towards cauliflower observed among Rhizoctonia AGs correlated with the infection rate, induction of host defence responses and pectin breakdown. All Rhizoctonia AGs studied penetrated the plant tissue, indicating all constitutive barriers of cauliflower were defeated and differences in aggressiveness were caused by inducible defence responses, including cell wall fortifications with phenolic compounds and callose.

Höfte Monica

2009-07-01

253

Determination of the Anastomosis Grouping and Virulence of Rhizoctonia spp. Associated with Potato Tubers Grown in Lincoln, New Zealand  

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Full Text Available A total of 58 isolates of Rhizoctonia spp. (46 R. solani and 12 binucleate Rhizoctonia were recovered from potato tubers showing black scurf disease symptom during the 2004 growing season in Lincoln, New Zealand. The isolates were assigned to 5 Anastomosis Groups (AG of R. solani AG-3 (54.34%, AG-5 (28.26%, AG-8 (8.69%, AG-4 (6.52% and AG-2-2 IIIB (2.17% and six anastomosis groups of binucleate Rhizoctonia, AG-K (25%, AG-Bi (25%, AG-Ba (8.33%, AG-C (8.33%, AG-D (8.33% and AG-E (8.33%. Two isolates of BNR did not anastomose with any of the tester strains and remain unidentified. In pathogenicity tests that were carried out on radish, carrot, lettuce, onion, tomato and hemp, it was found that all the isolates of both R. solani and binucleate Rhizoctonia to be virulent at varying degrees to these 6 plants species from different families. In these tests, isolates of AG-3 and AG-8 from R. solani population caused the highest and lowest disease severity on all 6 plant species, respectively. In population of binucleate Rhizoctonia, on the other hand, the highest and lowest disease severities were caused by the isolates of AG-D and AG-Ba on all test plants, respectively. When the results of the pathogenicity tests were examined in terms of the susceptibility levels of the plants, the most resistant plant was tomato against different AGs of R. solani and BNR. On the other hand, radish was the most susceptible plant species tested in this study against both R. solani and BNR isolates.

Reza Farrokhi-Nejad

2007-01-01

254

Some characteristic of Rhizoctonia spp. in sharp eyespot of wheat  

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Full Text Available Isolates of Rhizttctonia sp. with multinucleate and binucleate cells were obtained from sharp eyespot lesions on wheat culms in Olsztyn region. (NE Poland. These isolates were compared to isolates of AG-4 and GAG-1 testers with reference to cultural morphology of colony, growth rate, hyphal anastomosis and pathogenicity to wheat seedlings. The wheat binucleate isolates were similar in morphology of colonies and anastomosed with the Ceratubasidium anastomosis group GAG-1 tester isolates of R. cerealis. Growth rates on PDA ranged from 9 to 11 mm/24h for wheat isolates and from l to 11 mm/24 h for tester isolates GAG-1 of R. cerealis. The wheat multinucleate isolates were similar in morphology of colonies and anastomosed with Rhizoctonia solani Kühn group AG-4 tester isolate. R. solani AG-4 isolates were morphologically distinct from the R. cerealis isolates. These isolates on PDA were dark and grow rapidly (20-30 mm diam./24 h/20°C and significantly contrasted with slowly growing white-creamy isolates of R. cerealis (GAG-1. Isolates of R. solani (AG-4 and R. cerealis (GAG-I developed sharp eyespot lesions on culms and white head symptoms typical of the disease. None of the wheat isolates of R. cerealis (GAG-I caused root-rot on wheat seedlings. In the present work the classification system of vegetative groups of Rhizoctonia spp. in present work is also discussed.

Helena Furga?-W?grzycka

1996-12-01

255

DNA fingerprinting and anastomosis grouping reveal similar genetic diversity in Rhizoctonia species infecting turfgrasses in the transition zone of USA.  

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Rhizoctonia blight is a common and serious disease of many turfgrass species. The most widespread causal agent, Thanatephorus cucumeris (anamorph: R. solani), consists of several genetically different subpopulations. In addition, Waitea circinata varieties zeae, oryzae and circinata (anamorph: Rhizoctonia spp.) also can cause the disease. Accurate identification of the causal pathogen is important for effective management of the disease. It is challenging to distinguish the specific causal pathogen based on disease symptoms or macroscopic and microscopic morphology. Traditional methods such as anastomosis reactions with tester isolates are time consuming and sometimes difficult to interpret. In the present study universally primed PCR (UP-PCR) fingerprinting was used to assess genetic diversity of Rhizoctonia spp. infecting turfgrasses. Eighty-four Rhizoctonia isolates were sampled from diseased turfgrass leaves from seven distinct geographic areas in Virginia and Maryland. Rhizoctonia isolates were characterized by ribosomal DNA internal transcribed spacer (rDNA-ITS) region and UP-PCR. The isolates formed seven clusters based on ITS sequences analysis and unweighted pair group method with arithmetic mean (UPGMA) clustering of UP-PCR markers, which corresponded well with anastomosis groups (AGs) of the isolates. Isolates of R. solani AG 1-IB (n = 18), AG 2-2IIIB (n = 30) and AG 5 (n = 1) clustered separately. Waitea circinata var. zeae (n = 9) and var. circinata (n = 4) grouped separately. A cluster of six isolates of Waitea (UWC) did not fall into any known Waitea variety. The binucleate Rhizoctonia-like fungi (BNR) (n = 16) clustered into two groups. Rhizoctonia solani AG 2-2IIIB was the most dominant pathogen in this study, followed by AG 1-IB. There was no relationship between the geographic origin of the isolates and clustering of isolates based on the genetic associations. To our knowledge this is the first time UP-PCR was used to characterize Rhizoctonia, Waitea and Ceratobasidium isolates to their infra-species level. PMID:23709576

Amaradasa, B S; Horvath, B J; Lakshman, D K; Warnke, S E

2013-01-01

256

Heterokaryon formation in Thanatephorus cucumeris (Rhizoctonia solani) AG-1 IC.  

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Approximately 50 single-basidiospore isolates (SBIs) obtained from each of 16 field isolates of Thanatephorus cucumeris AG-1 IC were examined for heterokaryon formation. All SBIs obtained from each field isolate were divided into two mating groups (SBIs-M1 and SBIs-M2), and tufts of mycelia were formed in the contact zone between colonies of paired SBIs-M1 and -M2 based on 0.5 % charcoal agar medium. Tufts were produced from all possible pairing between SBIs from non-parental field isolates. Hyphal anastomosis reactions indicated no cell death and random cell death at the contact cell, and was not related to tuft formation. AFLP phenotypes of SBIs from each field isolate were not identical to each other and were different from their parental field isolate. AFLP phenotypes of the tuft isolates formed from SBIs-M1 and SBIs-M2 from each field isolate were heterokaryotic. Moreover, several SBIs also formed tufts with their parental and non-parental field isolates. AFLP phenotypes of these tuft isolates suggested that they were all heterokaryotic. Results of these experiments suggest that T. cucumeris AG-1 IC is heterothallic and bipolar, and that genetic exchange can occur between homokaryotic and heterokaryotic isolates (Buller phenomenon). PMID:18692371

Qu, Ping; Yamashita, Koji; Toda, Takeshi; Priyatmojo, Achmadi; Kubota, Mayumi; Hyakumachi, Mitsuro

2008-09-01

257

O papel de Rhizoctonia spp. binucleadas na indução de resistência a mela da soja / The role of binucleate Rhizoctonia spp. inducing resistance to the soybean foliar blight  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O papel de Rhizoctonia spp. binucleadas (RBN), no biocontrole de doenças causadas por R. solani Kühn em várias culturas, tem sido relatado na literatura. No entanto, não há informação, no Brasil, sobre o potencial de RBN como agentes de biocontrole contra doenças causadas por Rhizoctonia na soja. A [...] hipótese testada foi de que isolados de RBN podem induzir resistência na soja contra a mela, causada por R. solani do grupo de anastomose (AG) 1 IA. Desta forma, o objetivo deste trabalho foi avaliar isolados de RBN, obtidos de amendoim, feijão e soja quanto à capacidade de induzir resistência na soja contra a mela, em condições de casa de vegetação. Esta pesquisa evidencia a ação de RBN na indução de resistência em plantas de soja contra a mela. Entretanto, a manifestação e a efetividade do fenômeno de indução de resistência são dependentes da época de cultivo da soja. Abstract in english The role of non-pathogenic binucleate Rhizoctonia spp. (BNR) on the biocontrol of diseases caused by R. solani on many crops has been reported in the literature. However, in Brazil, there is no information about the potential of BNR as biocontrol agents against Rhizoctonia diseases on soybean. On th [...] is research we tested the hypothesis that BNR can induce resistance on soybean against the foliar blight caused by R. solani anastomosis group (AG) 1 IA. Thus, the objective of this research was to evaluate BNR isolates isolated from peanuts, snapbeans and soybean according to their ability for inducing resistance on soybean against the foliar blight disease, under greenhouse conditions. This research evidenced the role of BNR inducing resistance on soybeans against the foliar blight. However, both the occurrence and effectiveness of the phenomenon of induced resistance are dependent on the soybean cultivation season.

Marco Antonio, Basseto; Walter Veriano, Valério Filho; Elaine Costa, Souza; Paulo Cezar, Ceresini.

258

O papel de Rhizoctonia spp. binucleadas na indução de resistência a mela da soja = The role of binucleate Rhizoctonia spp. inducing resistance to the soybean foliar blight  

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Full Text Available O papel de Rhizoctonia spp. binucleadas (RBN, no biocontrole de doenças causadas por R. solani Kühn em várias culturas, tem sido relatado na literatura. No entanto, não há informação, no Brasil, sobre o potencial de RBN como agentes de biocontrole contradoenças causadas por Rhizoctonia na soja. A hipótese testada foi de que isolados de RBN podem induzir resistência na soja contra a mela, causada por R. solani do grupo de anastomose (AG 1 IA. Desta forma, o objetivo deste trabalho foi avaliar isolados de RBN, obtidos de amendoim, feijão e soja quanto à capacidade de induzir resistência na soja contra a mela, em condições de casa de vegetação. Esta pesquisa evidencia a ação de RBN na indução de resistência em plantas de soja contra a mela. Entretanto, a manifestação e a efetividade do fenômeno de indução de resistência são dependentes da época de cultivo da soja.The role of non-pathogenic binucleate Rhizoctonia spp. (BNR onthe biocontrol of diseases caused by R. solani on many crops has been reported in the literature. However, in Brazil, there is no information about the potential of BNR as biocontrol agents against Rhizoctonia diseases on soybean. On this research we tested thehypothesis that BNR can induce resistance on soybean against the foliar blight caused by R. solani anastomosis group (AG 1 IA. Thus, the objective of this research was to evaluate BNR isolates isolated from peanuts, snapbeans and soybean according to their ability forinducing resistance on soybean against the foliar blight disease, under greenhouse conditions. This research evidenced the role of BNR inducing resistance on soybeans against the foliar blight. However, both the occurrence and effectiveness of the phenomenon of induced resistance are dependent on the soybean cultivation season.

Marco Antonio Basseto

2008-04-01

259

Use of multispectral radiometry for assessment of rhizoctonia blight in creeping bentgrass.  

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ABSTRACT The ability to identify diseases early and quantify severity accurately is crucial in plant disease assessment and management. This study was conducted to assess changes in the spectral reflectance of sunlight from plots of creeping bentgrass during infection by Rhizoctonia solani, the cause of Rhizoctonia blight, and to evaluate multispectral radiometry as a tool to quantify Rhizoctonia blight severity. After inoculation of 6-year-old creeping bentgrass turf with R. solani anastomosis group 2-2, reflectance of sunlight from the foliar canopy was measured at light wavelengths of 460 nm (blue) to 810 nm (near infrared [NIR]), at 50-nm intervals. Visual estimates of disease severity and percentage of canopy reflectance were made daily throughout each of three epidemics of Rhizoctonia blight from the onset of visible symptoms until maximum disease severity was reached. In each experiment, linear regression analysis revealed a significant reduction in the percentage of NIR (760 and 810 nm) reflectance as disease severity increased. However, in the majority of analyses, regression models explained <50% of the variability between components. Multispectrum radiometry appears to function best when used to assess differences in disease severity at discrete points in time rather than over an entire epidemic. PMID:18944925

Raikes, C; Burpee, L L

1998-05-01

260

Método fácil y confiable para teñir núcleos en hongos del complejo Rhizoctonia / Easy and reliable method for nuclei staining of Rhizoctonia complex fungi  

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Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish En el complejo Rhizoctonia la morfología hifal y configuración del septo permiten diferenciar los géneros, mientras que las especies pueden ser distinguidas por la condición nuclear y el grosor de hifas “guías” ó la morfometría del teleomorfo. Para caracterizar las especies en uni, bi y multinuclead [...] as se han desarrollado varios métodos de tinción nuclear con acridina naranja, azules de anilina y tripano, diamina fenil indol (DAPI), giemsa, hematoxilina, orceina y safranina O. Algunos de esos procedimientos son rápidos, pero otros requieren técnicas especiales (fluorescencia) o consumen mucho tiempo y limitan la cantidad de muestras a procesar. Un nuevo método fue desarrollado durante análisis de anastomosis (AGs) en aislamientos de R. solani que atacan la papa cultivada en Mérida, Venezuela. El procedimiento es rápido, fácil, confiable y permite la manipulación simultánea de un número considerable de especimenes, y tanto el núcleo como el nucléolo conservan su integridad. El método fue probado exitosamente en 10 patrones de AGs de R. solani, y permitió separar 173 cepas multinucleadas y 3 binucleadas, todas del género Rhizoctonia. El método fue efectivo utilizando sustrato de agua-agar 2,4 % más PDA 0,39 %, en cultivos de 18 a 48 h fijado con formaldehído 4 % y coloreado con fucsina ácida 0,025 en ácido láctico 50 %. Abstract in english Hyphal morphology and septal structure configuration of the fungi included in Rhizoctonia complex allows for differentiation of genus, while species may be distinguished by nuclear condition and thickness of the runner hyphae, or teleomorph morphometry. For characterization of species in uni, bi, an [...] d multinucleate diverse methods of staining have been developed using acridine orange, aniline and trypan blue, diamine phenyl indole (DAPI), giemsa, hematoxiline, orcein and saphranin O. Some of these procedures are quick to perform, while others require special techniques (fluorescence) or are time consuming, which impose a limit on the number of samples that can be processed at a time. A new method of nuclei staining was developed during the analysis of anastomosis groups (AGs) of R. solani strains isolated from potato plants cultivated in Mérida, Venezuela. The procedure is quick, easy, and reliable, and allows for simultaneous manipulation of a significant number of samples, and both nucleus and nucleolus maintain their integrity. The method was successfully assayed in 10 different AGs testers of R. solani, and allowed separation of 173 multinucleate and 3 binucleate Rhizoctonia strains. Method effectiveness depends upon growth medium (water agar 2.4 % plus PDA 0.39 %), culture age (18-48 h), fixing agent (formaldehyde 4 %), and stain (fuchsin acid 0.025 % in lactic acid 50 %).

Luis, Cedeño.

 
 
 
 
261

Método fácil y confiable para teñir núcleos en hongos del complejo Rhizoctonia Easy and reliable method for nuclei staining of Rhizoctonia complex fungi  

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Full Text Available En el complejo Rhizoctonia la morfología hifal y configuración del septo permiten diferenciar los géneros, mientras que las especies pueden ser distinguidas por la condición nuclear y el grosor de hifas “guías” ó la morfometría del teleomorfo. Para caracterizar las especies en uni, bi y multinucleadas se han desarrollado varios métodos de tinción nuclear con acridina naranja, azules de anilina y tripano, diamina fenil indol (DAPI, giemsa, hematoxilina, orceina y safranina O. Algunos de esos procedimientos son rápidos, pero otros requieren técnicas especiales (fluorescencia o consumen mucho tiempo y limitan la cantidad de muestras a procesar. Un nuevo método fue desarrollado durante análisis de anastomosis (AGs en aislamientos de R. solani que atacan la papa cultivada en Mérida, Venezuela. El procedimiento es rápido, fácil, confiable y permite la manipulación simultánea de un número considerable de especimenes, y tanto el núcleo como el nucléolo conservan su integridad. El método fue probado exitosamente en 10 patrones de AGs de R. solani, y permitió separar 173 cepas multinucleadas y 3 binucleadas, todas del género Rhizoctonia. El método fue efectivo utilizando sustrato de agua-agar 2,4 % más PDA 0,39 %, en cultivos de 18 a 48 h fijado con formaldehído 4 % y coloreado con fucsina ácida 0,025 en ácido láctico 50 %.Hyphal morphology and septal structure configuration of the fungi included in Rhizoctonia complex allows for differentiation of genus, while species may be distinguished by nuclear condition and thickness of the runner hyphae, or teleomorph morphometry. For characterization of species in uni, bi, and multinucleate diverse methods of staining have been developed using acridine orange, aniline and trypan blue, diamine phenyl indole (DAPI, giemsa, hematoxiline, orcein and saphranin O. Some of these procedures are quick to perform, while others require special techniques (fluorescence or are time consuming, which impose a limit on the number of samples that can be processed at a time. A new method of nuclei staining was developed during the analysis of anastomosis groups (AGs of R. solani strains isolated from potato plants cultivated in Mérida, Venezuela. The procedure is quick, easy, and reliable, and allows for simultaneous manipulation of a significant number of samples, and both nucleus and nucleolus maintain their integrity. The method was successfully assayed in 10 different AGs testers of R. solani, and allowed separation of 173 multinucleate and 3 binucleate Rhizoctonia strains. Method effectiveness depends upon growth medium (water agar 2.4 % plus PDA 0.39 %, culture age (18-48 h, fixing agent (formaldehyde 4 %, and stain (fuchsin acid 0.025 % in lactic acid 50 %.

Luis Cedeño

2008-12-01

262

Método fácil y confiable para teñir núcleos en hongos del complejo Rhizoctonia / Easy and reliable method for nuclei staining of Rhizoctonia complex fungi  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish En el complejo Rhizoctonia la morfología hifal y configuración del septo permiten diferenciar los géneros, mientras que las especies pueden ser distinguidas por la condición nuclear y el grosor de hifas “guías” ó la morfometría del teleomorfo. Para caracterizar las especies en uni, bi y multinuclead [...] as se han desarrollado varios métodos de tinción nuclear con acridina naranja, azules de anilina y tripano, diamina fenil indol (DAPI), giemsa, hematoxilina, orceina y safranina O. Algunos de esos procedimientos son rápidos, pero otros requieren técnicas especiales (fluorescencia) o consumen mucho tiempo y limitan la cantidad de muestras a procesar. Un nuevo método fue desarrollado durante análisis de anastomosis (AGs) en aislamientos de R. solani que atacan la papa cultivada en Mérida, Venezuela. El procedimiento es rápido, fácil, confiable y permite la manipulación simultánea de un número considerable de especimenes, y tanto el núcleo como el nucléolo conservan su integridad. El método fue probado exitosamente en 10 patrones de AGs de R. solani, y permitió separar 173 cepas multinucleadas y 3 binucleadas, todas del género Rhizoctonia. El método fue efectivo utilizando sustrato de agua-agar 2,4 % más PDA 0,39 %, en cultivos de 18 a 48 h fijado con formaldehído 4 % y coloreado con fucsina ácida 0,025 en ácido láctico 50 %. Abstract in english Hyphal morphology and septal structure configuration of the fungi included in Rhizoctonia complex allows for differentiation of genus, while species may be distinguished by nuclear condition and thickness of the runner hyphae, or teleomorph morphometry. For characterization of species in uni, bi, an [...] d multinucleate diverse methods of staining have been developed using acridine orange, aniline and trypan blue, diamine phenyl indole (DAPI), giemsa, hematoxiline, orcein and saphranin O. Some of these procedures are quick to perform, while others require special techniques (fluorescence) or are time consuming, which impose a limit on the number of samples that can be processed at a time. A new method of nuclei staining was developed during the analysis of anastomosis groups (AGs) of R. solani strains isolated from potato plants cultivated in Mérida, Venezuela. The procedure is quick, easy, and reliable, and allows for simultaneous manipulation of a significant number of samples, and both nucleus and nucleolus maintain their integrity. The method was successfully assayed in 10 different AGs testers of R. solani, and allowed separation of 173 multinucleate and 3 binucleate Rhizoctonia strains. Method effectiveness depends upon growth medium (water agar 2.4 % plus PDA 0.39 %), culture age (18-48 h), fixing agent (formaldehyde 4 %), and stain (fuchsin acid 0.025 % in lactic acid 50 %).

Luis, Cedeño.

2008-12-01

263

Agroecological factors correlated to soil DNA concentrations of Rhizoctonia in dryland wheat production zones of Washington state, USA.  

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The necrotrophic soilborne fungal pathogens Rhizoctonia solani AG8 and R. oryzae are principal causal agents of Rhizoctonia root rot and bare patch of wheat in dryland cropping systems of the Pacific Northwest. A 3-year survey of 33 parcels at 11 growers' sites and 60 trial plots at 12 Washington State University cereal variety test locations was undertaken to understand the distribution of these pathogens. Pathogen DNA concentrations in soils, quantified using real-time polymerase chain reaction, were correlated with precipitation, temperature maxima and minima, and soil texture factors in a pathogen-specific manner. Specifically, R. solani AG8 DNA concentration was negatively correlated with precipitation and not correlated with temperature minima, whereas R. oryzae concentration was correlated with temperature minima but not with precipitation. However, both pathogens were more abundant in soils with higher sand and lower clay content. Principal component analysis also indicated that unique groups of meteorological and soil factors were associated with each pathogen. Furthermore, tillage did not affect R. oryzae but affected R. solani AG8 at P = 0.06. Lower soil concentrations of R. solani AG8 but not R. oryzae occurred when the previously planted crop was a broadleaf (P solani AG8 concentrations were consistent with the general distribution of bare patch symptoms, based on field observations and surveys of other pathogens, but was present at many sites in which bare patch symptoms were not evident. Management of Rhizoctonia root rot and bare patch should account for the likelihood that each pathogen is affected by a unique group of agroecological variables. PMID:24915426

Okubara, Patricia A; Schroeder, Kurtis L; Abatzoglou, John T; Paulitz, Timothy C

2014-07-01

264

Caracterização de isolados de Rhizoctonia spp. e identificação de novos grupos de anastomose em jardim clonal de eucalipto Characterization of isolates of Rhizoctonia spp. and identification of new anastomosis groups in eucalyptus clonal nurseries  

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Full Text Available Espécies de Rhizoctonia causam queima foliar em brotações de jardim clonal e podridão de estacas durante o enraizamento, que podem limitar a clonagem do eucalipto, por estaquia. Diante da importância do patógeno para a cultura e da falta de estudos sobre a diversidade de isolados, esse trabalho objetivou caracterizar isolados e relatar novos grupos de anastomose de Rhizoctonia spp. em jardim clonal de eucalipto. Os isolados obtidos nas diferentes fases de propagação por estaquia foram caracterizados quanto ao número de núcleos nas células vegetativas, agrupados segundo as características morfológicas das colônias e identificados quanto aos grupos de anastomose, incluindo auxotrofia por tiamina. Avaliou-se, também, a virulência ao eucalipto e o efeito da temperatura no crescimento micelial dos isolados. Não se detectou correlação entre os agrupamentos morfológicos e reações de anastomose. Constatou-se, também, que a população de Rhizoctonia spp., nos solos de jardins clonais, é constituída por ampla gama de isolados, predominantemente binucleados, com diferentes graus de virulência a eucalipto. Os isolados binucleados e os multinucleados, tiveram a mesma tendência de crescimento em relação à temperatura, com ótimo para a taxa de crescimento entre 25-30 ºC. Observou-se, pela primeira vez, isolados de R. solani AG2-2 IIIB e os binucleados de Rhizoctonia spp., AG-P e AG-O, como agentes etiológicos da podridão de estacas em casa de vegetação, e os isolados binucleados AG-A e AG-L em solo de jardim clonal de eucalipto.Rhizoctonia spp. cause shoot and leaf blight of eucalyptus in clonal hedges as well as cuttings. Despite the importance of Rhizoctonia spp. to eucalyptus, little is known about their diversity. Thus, we characterized isolates and report new anastomosis groups in a eucalyptus clonal hedge. Isolates obtained at different stages of cutting propagation were characterized according to the number of nuclei in vegetative cells, grouped by morphological characteristics of the colony, anastomosis group, and thiamine auxotrophism. The isolates were also evaluated for virulence on eucalyptus and effect of temperature on their mycelial growth. No correlation between morphological grouping and anastomosis reaction was detected. A wide range of isolates, predominantly binucleate, forms the population of Rhizoctonia spp. present in the soil of clonal hedges, which differed in virulence to eucalyptus. Binucleate and multinucleate isolates had similar growth features at different temperatures, with an optimum growth rate between 25-30 ºC. Isolates of R. solani AG2-2 IIIB and binucleate isolates of Rhizoctonia spp., AG-P and AG-O, as agents of cutting rot, and binucleate isolates AG-A and AG-L in the soil of eucalyptus clonal hedge are reported for the first time.

Eugenio Sanfuentes

2007-06-01

265

Plant Disease Lesson: Rhizoctonia Diseases of Turfgrass  

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This plant disease lesson on Rhizoctonia diseases of turfgrass (caused by the fungi Rhizoctonia species) includes information on symptoms and signs, pathogen biology, disease cycle and epidemiology, disease management, and the significance of the disease. Selected references are listed and a glossary is also available for use with this resource.

Lane P. Tredway (University of Georgia, Athens;); Lee L. Burpee (University of Georgia, Griffin;)

2001-11-09

266

Use of SCAR-PCR in diagnostics of stem base pathogens of the Rhizoctonia and Oculimacula genus  

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Full Text Available The aim of the paper is to compare the efficacy of SCAR-PCR assay and conventional diagnostic technique (visual assessment, isolation on PDA medium in the identification of fungi from the genera Rhizoctonia and Oculimacula from winter triticale, rye, and barley during the shooting stage. The usefulness of molecular diagnosis of fungal pathogens in crop plants has been demonstrated. The application of SCAR- -PCR assay allowed early detection of the following pathogens: O. yallundae, O. acuformis, R. cerealis and R. solani, in plant tissues. This method was particularly effective in detection of R. solani. The research showed the usefulness of PCR markers for early detection of fungal pathogens, even if symptoms were not visible. Using the PCR technique, especially in combination with conventional methods, substantially increases the precision and effectiveness of disease diagnostics.

Grzegorz Lema?czyk

2011-12-01

267

Caracterização de isolados de Rhizoctonia spp., associados à mela do feijão-caupi (Vigna unguiculata, coletados em Roraima Characterization of Rhizoctonia spp. associated with cowpea web (Vigna unguiculata blight in Roraima, Brazil  

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Full Text Available A mela causada pelo fungo Rhizoctonia solani (teleomorfo Thanatephorus cucumeris é a principal doença que afeta a cultura do feijão-caupi (Vigna unguiculata no Estado de Roraima. Este trabalho teve como objetivo caracterizar 28 isolados de Rhizoctonia spp. obtidos de plantas de feijão-caupi com sintoma de mela, coletados em ecossistemas de mata e de cerrado em Roraima. Foram avaliados o número de núcleos, a taxa de crescimento micelial, a formação e o tamanho de microescleródios, o grupo de anastomose e realizado teste de patogenicidade. Um isolado proveniente do cerrado foi identificado como binucleado e os demais isolados, de mata e de cerrado, como multinucleados. A taxa de crescimento micelial, em meio batata-dextrose-agar a 25 ºC e escuro contínuo, variou de 2,1-5,3 cm.dia-1 para os isolados de mata e de 2,7-5,8 cm.dia-1 para os isolados de cerrado. Nestas mesmas condições, após três a quatro dias foi observada a formação de microescleródios. Dois grupos foram diferenciados: um grupo com formação de 10-50 microescleródios.placa-1, em forma de tufos, inicialmente brancos e tornando-se marrom claro, de 1-2 mm (maioria dos isolados de mata e outro grupo com mais de 100 microescleródios.placa-1, de coloração marrom e 68-541 µm (maioria dos isolados de cerrado. Dos 28 isolados coletados, 24 foram identificados como pertencentes ao grupo de anastomose GA1-1A de Rhizoctonia solani.The web blight caused by the fungus Rhizoctonia solani (teleomorph Thanatephorus cucumeris is an important disease of cowpea [Vigna unguiculata (L. Walp.] in Roraima state, Brazil. The aim of this work was to characterize 28 Rhizoctonia spp. isolates from cowpea plants with web blight, collected in two ecosystems (savannah and forest in Roraima state. The characteristics evaluated were nuclear number, radial growth rate, the presence and morphology of microsclerotia, anastomosis group (AG and pathogenicity test. One savannah isolate was binucleate and the others, savannah and forest isolates, were multinucleate. The radial growth rate on potato-dextrose-aga, at 25 ºC in the dark, was 2.1 to 5.3 cm.day-1 for forest isolates and 2.7 to 5.8 cm.day-1 for savannah isolates. In these conditions, after three to four days, microsclerotia formation was observed. Two types of microsclerotia were differentiated: one type of 10 to 50 microsclerotia.Petri dish-1, formed as flat sclerotia mass, which was white when young and pale brown at maturity, 1 to 2 mm in diameter (most forest isolates and another type of 100 microsclerotia.Petri dish-1, brown color, 68 to 541 µm in diameter (most savannah isolates. Among 28 Rhizoctonia isolates collected in Roraima state, 24 anastomosed with AG1-1A of Rhizoctonia solani.

Kátia L. Nechet

2006-10-01

268

Caracterização de isolados de Rhizoctonia spp., associados à mela do feijão-caupi (Vigna unguiculata), coletados em Roraima / Characterization of Rhizoctonia spp. associated with cowpea web (Vigna unguiculata) blight in Roraima, Brazil  

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Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A mela causada pelo fungo Rhizoctonia solani (teleomorfo Thanatephorus cucumeris) é a principal doença que afeta a cultura do feijão-caupi (Vigna unguiculata) no Estado de Roraima. Este trabalho teve como objetivo caracterizar 28 isolados de Rhizoctonia spp. obtidos de plantas de feijão-caupi com si [...] ntoma de mela, coletados em ecossistemas de mata e de cerrado em Roraima. Foram avaliados o número de núcleos, a taxa de crescimento micelial, a formação e o tamanho de microescleródios, o grupo de anastomose e realizado teste de patogenicidade. Um isolado proveniente do cerrado foi identificado como binucleado e os demais isolados, de mata e de cerrado, como multinucleados. A taxa de crescimento micelial, em meio batata-dextrose-agar a 25 ºC e escuro contínuo, variou de 2,1-5,3 cm.dia-1 para os isolados de mata e de 2,7-5,8 cm.dia-1 para os isolados de cerrado. Nestas mesmas condições, após três a quatro dias foi observada a formação de microescleródios. Dois grupos foram diferenciados: um grupo com formação de 10-50 microescleródios.placa-1, em forma de tufos, inicialmente brancos e tornando-se marrom claro, de 1-2 mm (maioria dos isolados de mata) e outro grupo com mais de 100 microescleródios.placa-1, de coloração marrom e 68-541 µm (maioria dos isolados de cerrado). Dos 28 isolados coletados, 24 foram identificados como pertencentes ao grupo de anastomose GA1-1A de Rhizoctonia solani. Abstract in english The web blight caused by the fungus Rhizoctonia solani (teleomorph Thanatephorus cucumeris) is an important disease of cowpea [Vigna unguiculata (L.) Walp.] in Roraima state, Brazil. The aim of this work was to characterize 28 Rhizoctonia spp. isolates from cowpea plants with web blight, collected i [...] n two ecosystems (savannah and forest) in Roraima state. The characteristics evaluated were nuclear number, radial growth rate, the presence and morphology of microsclerotia, anastomosis group (AG) and pathogenicity test. One savannah isolate was binucleate and the others, savannah and forest isolates, were multinucleate. The radial growth rate on potato-dextrose-aga, at 25 ºC in the dark, was 2.1 to 5.3 cm.day-1 for forest isolates and 2.7 to 5.8 cm.day-1 for savannah isolates. In these conditions, after three to four days, microsclerotia formation was observed. Two types of microsclerotia were differentiated: one type of 10 to 50 microsclerotia.Petri dish-1, formed as flat sclerotia mass, which was white when young and pale brown at maturity, 1 to 2 mm in diameter (most forest isolates) and another type of 100 microsclerotia.Petri dish-1, brown color, 68 to 541 µm in diameter (most savannah isolates). Among 28 Rhizoctonia isolates collected in Roraima state, 24 anastomosed with AG1-1A of Rhizoctonia solani.

Kátia L., Nechet; Bernardo A., Halfeld-Vieira.

2006-10-01

269

Transformation of soil microbial community structure and rhizoctonia-suppressive potential in response to apple roots.  

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ABSTRACT Changes in the composition of soil microbial communities and relative disease-suppressive ability of resident microflora in response to apple cultivation were assessed in orchard soils from a site possessing trees established for 1 to 5 years. The fungal community from roots of apple seedlings grown in noncultivated orchard soil was dominated by isolates from genera commonly considered saprophytic. Plant-pathogenic fungi in the genera Phytophthora, Pythium, and Rhizoctonia constituted an increasing proportion of the fungal community isolated from seedling roots with increasing orchard block age. Bacillus megaterium and Burkholderia cepacia dominated the bacterial communities recovered from noncultivated soil and the rhizosphere of apple seedlings grown in orchard soil, respectively. Populations of the two bacteria in their respective habitats declined dramatically with increasing orchard block age. Lesion nematode populations did not differ among soil and root samples from orchard blocks of different ages. Similar changes in microbial communities were observed in response to planting noncultivated orchard soil to five successive cycles of 'Gala' apple seedlings. Pasteurization of soil had no effect on apple growth in noncultivated soil but significantly enhanced apple growth in third-year orchard block soil. Seedlings grown in pasteurized soil from the third-year orchard block were equal in size to those grown in noncultivated soil, demonstrating that suppression of plant growth resulted from changes in the composition of the soil microbial community. Rhizoctonia solani anastomosis group 5 (AG 5) had no effect on growth of apple trees in noncultivated soil but significantly reduced the growth of apple trees in soil from third-year orchard soil. Changes in the ability of the resident soil microflora to suppress R. solani AG 5 were associated with reductions in the relative populations of Burkholderia cepacia and Pseudomonas putida in the rhizosphere of apple. PMID:18944736

Mazzola, M

1999-10-01

270

77 FR 18806 - Fluxapyroxad; Receipt of Application for Emergency Exemption for Use on Rice in Louisiana...  

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...blight caused by the fungus, Rhizoctonia solani. The applicant proposes the...blight caused by the fungus Rhizoctonia solani. Information in accordance...in rice caused by the fungus Rhizoctonia solani. Rhizoctonia solani has...

2012-03-28

271

[Levanase from Fusarium solani-68].  

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Extracellular levanase was isolated from the culture of Fusarium solani-68 by ammonium sulfate precipitation at 0.8 saturation and purified in part by Sephadex G-150 gel chromatography. Levanase showed maximum activity at pH = 6.0 and t = 45 degrees C. The levanase reaction (hydrolysis of high molecular levane with a molecular weight of 1--5 min) reached a maximum rate at a polysaccharide concentration of 6.7 mg/ml, Michaelis constant being 1.5 X 10(-6) M. Levanase remained stable at pH 5.4--7.5 and temperature 40--45 degrees C. PMID:7433428

Elisashvili, V I; Loitsianskaia, M S; Baranova, T I; Bangura, A

1980-01-01

272

Cropping Systems and Cultural Practices Determine the Rhizoctonia Anastomosis Groups Associated with Brassica spp. in Vietnam.  

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Ninety seven Rhizoctonia isolates were collected from different Brassica species with typical Rhizoctonia symptoms in different provinces of Vietnam. The isolates were identified using staining of nuclei and sequencing of the rDNA-ITS barcoding gene. The majority of the isolates were multinucleate R. solani and four isolates were binucleate Rhizoctonia belonging to anastomosis groups (AGs) AG-A and a new subgroup of A-F that we introduce here as AG-Fc on the basis of differences in rDNA-ITS sequence. The most prevalent multinucleate AG was AG 1-IA (45.4% of isolates), followed by AG 1-ID (17.5%), AG 1-IB (13.4%), AG 4-HGI (12.4%), AG 2-2 (5.2%), AG 7 (1.0%) and an unknown AG related to AG 1-IA and AG 1-IE that we introduce here as AG 1-IG (1.0%) on the basis of differences in rDNA-ITS sequence. AG 1-IA and AG 1-ID have not been reported before on Brassica spp. Pathogenicity tests revealed that isolates from all AGs, except AG-A, induced symptoms on detached leaves of several cabbage species. In in vitro tests on white cabbage and Chinese cabbage, both hosts were severely infected by AG 1-IB, AG 2-2, AG 4-HGI, AG 1-IG and AG-Fc isolates, while under greenhouse conditions, only AG 4-HGI, AG 2-2 and AG-Fc isolates could cause severe disease symptoms. The occurrence of the different AGs seems to be correlated with the cropping systems and cultural practices in different sampling areas suggesting that agricultural practices determine the AGs associated with Brassica plants in Vietnam. PMID:25372406

Hua, Gia Khuong Hoang; Bertier, Lien; Soltaninejad, Saman; Höfte, Monica

2014-01-01

273

Cropping Systems and Cultural Practices Determine the Rhizoctonia Anastomosis Groups Associated with Brassica spp. in Vietnam  

Science.gov (United States)

Ninety seven Rhizoctonia isolates were collected from different Brassica species with typical Rhizoctonia symptoms in different provinces of Vietnam. The isolates were identified using staining of nuclei and sequencing of the rDNA-ITS barcoding gene. The majority of the isolates were multinucleate R. solani and four isolates were binucleate Rhizoctonia belonging to anastomosis groups (AGs) AG-A and a new subgroup of A-F that we introduce here as AG-Fc on the basis of differences in rDNA-ITS sequence. The most prevalent multinucleate AG was AG 1-IA (45.4% of isolates), followed by AG 1-ID (17.5%), AG 1-IB (13.4%), AG 4-HGI (12.4%), AG 2-2 (5.2%), AG 7 (1.0%) and an unknown AG related to AG 1-IA and AG 1-IE that we introduce here as AG 1-IG (1.0%) on the basis of differences in rDNA-ITS sequence. AG 1-IA and AG 1-ID have not been reported before on Brassica spp. Pathogenicity tests revealed that isolates from all AGs, except AG-A, induced symptoms on detached leaves of several cabbage species. In in vitro tests on white cabbage and Chinese cabbage, both hosts were severely infected by AG 1-IB, AG 2-2, AG 4-HGI, AG 1-IG and AG-Fc isolates, while under greenhouse conditions, only AG 4-HGI, AG 2-2 and AG-Fc isolates could cause severe disease symptoms. The occurrence of the different AGs seems to be correlated with the cropping systems and cultural practices in different sampling areas suggesting that agricultural practices determine the AGs associated with Brassica plants in Vietnam. PMID:25372406

Soltaninejad, Saman; Höfte, Monica

2014-01-01

274

Caracterização de isolados de Rhizoctonia spp. e identificação de novos grupos de anastomose em jardim clonal de eucalipto / Characterization of isolates of Rhizoctonia spp. and identification of new anastomosis groups in eucalyptus clonal nurseries  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Espécies de Rhizoctonia causam queima foliar em brotações de jardim clonal e podridão de estacas durante o enraizamento, que podem limitar a clonagem do eucalipto, por estaquia. Diante da importância do patógeno para a cultura e da falta de estudos sobre a diversidade de isolados, esse trabalho obje [...] tivou caracterizar isolados e relatar novos grupos de anastomose de Rhizoctonia spp. em jardim clonal de eucalipto. Os isolados obtidos nas diferentes fases de propagação por estaquia foram caracterizados quanto ao número de núcleos nas células vegetativas, agrupados segundo as características morfológicas das colônias e identificados quanto aos grupos de anastomose, incluindo auxotrofia por tiamina. Avaliou-se, também, a virulência ao eucalipto e o efeito da temperatura no crescimento micelial dos isolados. Não se detectou correlação entre os agrupamentos morfológicos e reações de anastomose. Constatou-se, também, que a população de Rhizoctonia spp., nos solos de jardins clonais, é constituída por ampla gama de isolados, predominantemente binucleados, com diferentes graus de virulência a eucalipto. Os isolados binucleados e os multinucleados, tiveram a mesma tendência de crescimento em relação à temperatura, com ótimo para a taxa de crescimento entre 25-30 ºC. Observou-se, pela primeira vez, isolados de R. solani AG2-2 IIIB e os binucleados de Rhizoctonia spp., AG-P e AG-O, como agentes etiológicos da podridão de estacas em casa de vegetação, e os isolados binucleados AG-A e AG-L em solo de jardim clonal de eucalipto. Abstract in english Rhizoctonia spp. cause shoot and leaf blight of eucalyptus in clonal hedges as well as cuttings. Despite the importance of Rhizoctonia spp. to eucalyptus, little is known about their diversity. Thus, we characterized isolates and report new anastomosis groups in a eucalyptus clonal hedge. Isolates o [...] btained at different stages of cutting propagation were characterized according to the number of nuclei in vegetative cells, grouped by morphological characteristics of the colony, anastomosis group, and thiamine auxotrophism. The isolates were also evaluated for virulence on eucalyptus and effect of temperature on their mycelial growth. No correlation between morphological grouping and anastomosis reaction was detected. A wide range of isolates, predominantly binucleate, forms the population of Rhizoctonia spp. present in the soil of clonal hedges, which differed in virulence to eucalyptus. Binucleate and multinucleate isolates had similar growth features at different temperatures, with an optimum growth rate between 25-30 ºC. Isolates of R. solani AG2-2 IIIB and binucleate isolates of Rhizoctonia spp., AG-P and AG-O, as agents of cutting rot, and binucleate isolates AG-A and AG-L in the soil of eucalyptus clonal hedge are reported for the first time.

Eugenio, Sanfuentes; Acelino C., Alfenas; Luiz A., Maffia; Reginaldo G., Mafia.

2007-06-01

275

SIDEROPHORE PRODUCING Pseudomonas AS PATHOGENIC Rhisoctonia solani AND Botrytis cinerea ANTAGONISTS  

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Full Text Available Pseudomonas aeruginosa, Pseudomonas putida biovar B, Pseudomonas marginalis y Burkholderia cepacia, aisladas de rizosfera y filosfera de plantas de rosa y alstroemeria, identificadas por ensayos bioquímicos y cultivadas en medio King B, mostraron propiedades antagónicas contra los patógenos (se usó medio PDA agar par el cultivo Rhizoctonia solani y Botrytis cinerea. Estas propiedades coincidieron con la presencia de un sideróforo, sustancia polar con bandas de absorción en 260 nm y 402 nm. Se observó incremento del crecimiento longitudinal de las plantas, medido sobre el tallo central, por influencia de P. putida biovar B, P. aeruginosa y P. marginalis. El crecimiento de rizomas (a: 0.05 fue notorio bajo la influencia de P. marginalis.

Martha Páez

2005-06-01

276

Caracterização de isolados de Rhizoctonia associados à queima foliar em Roraima = Characterization of Rhizoctonia isolates associated with foliar blight in Roraima.  

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Full Text Available O objetivo desse trabalho foi caracterizar isolados do fungo Rhizoctonia associados à queima foliar, obtidos de hospedeiros de importância econômica no estado de Roraima. Os isolados foram obtidos de plantas de feijão-caupi (Vigna unguiculata, soja (Glycine max, seringueira (Hevea brasiliensis, melancia (Citrullus lanatus, alface (Lactuca sativa e feijão-guandu (Cajanus cajan. Os parâmetros utilizados foram números de núcleos, grupo de anastomose e as características culturais da colônia, taxa de crescimento micelial e a formação de escleródios nos meios de cultura: batata dextrose agar (BDA, BDA+asparagina, BDA+extrato de levedura, Czapek Agar, maltose-peptona-agar, soil extract agar, sacarose-yeast-asparagina e V-8. Todos os 10 isolados estudados foram caracterizados como multinucleados e pertencentes à espécie Rhizoctonia solani. Três isolados de feijão-caupi, um de soja e o isolado de melancia foram identificados como AGI-1A e um isolado de feijãocaupi, um de soja e o isolado de feijão-guandu como AGI-1B. O isolado de seringueira não foi identificado como nenhum dos padrões de anastomose utilizado. Para a maioria dos isolados as maiores taxas de crescimento micelialforam obtidas no meio de cultura Soil Extract Agar. Dois tipos de escleródios, característicos do grupo AGI, foram observados: formação de 2-20 tufos placa-1 coloração variável, 1-2 mm e formação de 38-611 microescleródios placa-1, de coloração marrom, medindo 100 ?m. A produção e o tipo de escleródio variaram com o isolado e o meio de cultura utilizado.The aim of this work was to characterize Rhizoctonia isolates associated with foliar blight symptom from hosts with economic importance at Roraima state. The isolates were recovered from cowpea (Vigna unguiculata, soybean (Glycine max, rubber tree (Hevea brasiliensis, watermelon (Citrullus lanatus, lettuce (Lactuca sativa and pigeonpea (Cajanus cajan. The evaluated characteristics were nuclear number, anastomosis group (AG and cultural characteristics, radial growth rate and the presence and morphology of sclerotia on the following media: potato dextrose agar (PDA, PDA+asparagine, PDA+yeast extract, Czapek Agar, maltose-peptone-agar,soil extract agar, sucrose-yeast-asparagine and V-8. All the 10 isolates evaluated were multinucleate and identified as Rhizoctonia solani. Three cowpea isolates, one soybean isolate and the watermelon isolate anastomosed with AG1-1A and one cowpea isolates, one soybean isolate and the pigeonpea isolate with AGI-1B. The rubber treeisolate was not identified with no anastomosis groups used in this study. Biggest radial growth rates were observed on the medium Soil Extract for most of the isolates. Two types of sclerotia, AGI typic were differentiated: one type of 2-20 flat sclerotia.Petri dish-1, variable colors, 1 to 2 mm in diameter and another type of 38-611 microsclerotia. Petri dish-1, brown color, 100 ?m in diameter. The number and sclerotia type were variable with the isolate and themedia used.

Dayane Rodrigues Youssef

2012-08-01

277

SELECCIÓN DE AISLAMIENTOS DE Trichoderma spp. CANDIDATOS A BIOFUNGICIDAS PARA EL CONTROL DE Rhizoctonia sp. EN ARROZ / SELECTION OF Trichoderma spp. ISOLATE CANDIDATES TO BIOFUNGICIDES FOR THE CONTROL OF Rhizoctonia sp. ON RICE  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish El Tizón de la Vaina, causado por el hongo Rhizoctonia solani Kühn, es considerada la segunda enfermedad de importancia en el cultivo del arroz, en Cuba y el mundo. La potencialidad de aislados del género Trichoderma como antagonista de patógenos del suelo es reconocida y muestra resultados positivo [...] s sobre R. solani. El presente trabajo tiene como objetivo seleccionar los aislamientos de Trichoderma spp. más promisorios en dependencia de su antagonismo in vitro y su eficacia en condiciones semicontroladas y de campo, para el biocontrol de Rhizoctonia sp. El antagonismo se evaluó por el método del cultivo dual, donde se observó la competencia por el sustrato, micoparasitismo y la antibiosis. Se calculó el porcentaje de inhibición del crecimiento radial (PICR) a las 72 horas y los aislados que presentaron más de un 60 PICR y al menos dos tipos de interacción hifal se seleccionaron para evaluar su eficacia técnica (ET) sobre el patógeno en condiciones semicontroladas. Los aislamientos con una ET superior al 80% fueron seleccionados para ser evaluados en canteros tecnificados en campo. Los resultados mostraron que el 98,31% de los aislados presentaron alta capacidad antagónica, con diferentes tipos de interacción hifal como lisis, vacuolización, enrollamiento y penetración, de los que fueron seleccionados once. De ellos siete mostraron una ET superior al 80% en condiciones semicontroladas. Como promisorios para el control de la enfermedad en campo se destacaron los aislamientos 17, 75 y 78 con una ET superior al 90%. Abstract in english Sheath blight, caused by Rhizoctonia solani Kühn is considered the second important disease on rice in Cuba and the world. Trichoderma potentiality as antagonist of soil pathogen is recognized with positive results on R. solani. The present work had as objective to select the best Trichoderma isolat [...] es according to their in vitro antagonism and efficacy in the control of Rhizoctonia sp. in greenhouse and in the field. Antagonism was evaluated by the dual culture method, where the competition by the substrate, mycoparasitism and antibiosis were observed. The inhibition percentage of radial growth (IPRG) was calculated at 72 hours. The isolates with more than 60 PICR and at least two types of hyphal interaction were selected for being tested under greenhouse conditions, where the selection criterion was the technical efficacy (TE) under these conditions. Isolates with a TE higher than 80% were selected for field screening. The results showed that the 98,31% of the isolates had high antagonist capacity. They presented several hyphal interaction types such as lyses, vacuolization, coiling and penetration. Eleven Trichoderma isolates were selected in vitro. Of them, seven showed a TE higher than 80% in greenhouse. As promissories for the disease control in the field, isolates: 17, 75 and 78 with a TE higher than 90% were those highlighted under these conditions.

B, Martínez; Yusimy, Reyes; Danay, Infante; E, González; Heyker, Baños; A, Cruz.

278

Genetic diversity among isolates of stemphylium solani from cotton  

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The fungus Stemphylium solani causes leaf blight of tomato (Lycopersicon esculentum) in Brazil. In recent years, severe epidemics of a new leaf blight of cotton (Gossipium hyrsutum) caused by S. solani occurred in three major cotton-growing Brazilian states (PR, MT and GO). Molecular analysis was performed to assess the genetic diversity among the S. solani isolates from cotton, and to verify their relationship with representative S. solani isolates from tomato. Random amplified polymorphic D...

Mehta, Y. R.

2001-01-01

279

Efecto de la solarización sobre Rhizoctonia spp. en semilleros de tomate, Lycopersicum esculentum, var. tropic  

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Full Text Available En Palmira (Valle, Colombia se comparó la solarización del suelo (cubrimiento con láminas de polietileno durante 2, 4 y 6 semanas, con un producto químico (Dazomet para la desinfestación de semilleros abonados con conejinaza (2 kg en 1.44 m2 y sin abonar, en presiembra. El suelo se inoculó con una mezcla de cuatro aislamientos de Rhizoctonia solani patogénicos a tomate variedad Tropic. En los suelos solarizados se alcanzaron temperaturas de 49.7 y 44.8 C a 5 y 10 cm de profundidad respectivamente y 41.6 y 38.8C en los testigos a las mismas profundidades. La solarización redujo la población de Rhizoctonia, en promedio, a 0.8 U.F.C (unidades formadoras de colonias por 100 g de suelo, en el primer ensayo (septiembre-octubre de 1987 y a cero en el segundo ensayo (enero-febrero de 1988; el Dazomet la redujo a cero en los dos ensayos. El testigo presentó un promedio de 24.6 U.F.C para los dos ensayos. El número de plántulas por surco fue mayor en los suelos tratados (solarización y producto químico lo mismo que el porcentaje de plántulas sanas (93 %, en los dos ensayos; el testigo presentó 52.3 y 88.7% plántulas sanas en los dos ensayos respectivamente. En los semilleros abonados el número de plántulas por surco fue menor en 3.3 (solarización y 15.3 % (producto químico para el primer ensayo, pero fue mayor, 19.2 y 9.5%, en el segundo ensayo.A research was carry out in Palmira (Valle, Colombia to test the solarization (poliethylene mulch. The experimental design consisted in "random blocks" and ten treatments obtained from the following factors combination: soil solarization during 2, 4 and 6 weeks, chemical treatrnent (Dazornet, control, all of them with and without application of rabbit manure (2 kg. The plot size was 1.44 m2. The soil was inoculated with the mixture of four isolations of Rhizoctonia solani which were pathogenics to the tomato (Tropic Variety. Temperatures of 49.7oC and 44.8oC at 5 and 10 cm deep respectively were reached in the soil under solarization treatment. The control reached temperatures of 41.6 y 38.8oC at the same depths. Rhizoctonia population was reduced to 0.8 colony formation units (C F U per 100 g of soil in the solarization treatment, during the first experiment (september to october 1987. In the second experiment (january to february 1988 the CFU was reduced to zero. The chemical treatment reduced the CFU to zero in both experiments. The control plots showed and average of 24.6 CFU during both experiments. The number of seedlings per row and the number of healthy plants (93% in both experiments was greater in the soil under chemical and solarization treatment than the control treatment. This showed 52.3 % and 88.7% of healthy plants in both experiments. The plots where the manure was applied the number of plants per row decreased in 3.3 (solarization and 15.3 % (chemical, during the first experiment. The second experiment showed that the number of plants per row increased in 19.2% and 9.5% to the same treatments.

Bravo Otero Nelson

1990-12-01

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The heterogeneity of the rDNA-ITS sequence and its phylogeny in Rhizoctonia cerealis, the cause of sharp eyespot in wheat.  

Science.gov (United States)

The sequence heterogeneity of the ribosomal internal transcribed spacer (ITS) region was investigated for Rhizoctonia cerealis isolates from the anastomosis group AG-DI. Although sequence variability of the ITS has been reported in a few multinucleate R. solani isolates, it has very rarely been reported in binucleate Rhizoctonia spp. isolates and has never been described in R. cerealis, the pathogen of wheat sharp eyespot. In this study, the ITS regions of 15 R. cerealis isolates were cloned and sequenced. The results revealed more than one different ITS sequence within each isolate. This is the first evidence of ITS sequence heterogeneity in R. cerealis. Based on these ITS sequences, different sequences of one isolate did not cluster in one clade, but all of the sequences of the 15 isolates were clustered in the anastomosis subgroup AG-DI, suggesting that the heterogeneity of the ITS did not affect the molecular identification of their anastomosis group. Haplotype analyses indicated that there might be three evolutionary origins of R. cerealis, or a recombination event could be the cause of different ITS sequences in one genome. This study demonstrates the variability and the evolution of Rhizoctonia, especially binucleate R. cerealis. These findings will help design disease control strategies. PMID:23839120

Li, Wei; Sun, Haiyan; Deng, Yuanyu; Zhang, Aixiang; Chen, Huaigu

2014-02-01

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