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Detection of Sclerotinia sclerotiorum using qPCR assay and comparison between three qPCR systems to check sensitivityPatil, Neeraj January 2021 (has links)
Sclerotinia sclerotiorum is a pathogenic fungus that infects around 400 species of host plants. Stem rot disease caused by this fungus is economically disastrous for Brassica napus cultivators in Sweden. Due to the lack of disease resistant cultivars, disease management has been solely dependent on fungicide application. The current disease prediction models are not scientifically accurate and take into account factors such as weather, previous disease incidence, and conomic effects which often result in unnecessary and excessive use of fungicides by cultivators. Real-Time Polymerase Chain Reaction has proven to be the fastest, most accurate and reliable technique for detecting plant pathogens as it gives an idea about disease severity by measuring pathogen concentration in environmental samples. Reproducible and able qPCR assays have the potential of being the main principle on which more scientifically accurate plant disease prediction and management models an be developed. The aim of this study was to validate a previously established qPCR assay to detect S. sclerotiorum. An absolute quantification experiment was performed by using plasmid DNA cloned with a target gene as template. Further, three different qPCR machines were compared to make a plausible conclusion regarding their sensitivity and efficiency in detecting minuscule amounts of DNA from the environment. While a solid conclusion could not be reached regarding the sensitivity of each of these machines, this study pointed out some basic trends about each machine that may help researchers in selecting the most efficient qPCR system when working with detection of plant pathogens.
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Analyses multidimensionnelles des effets de la rotation et d'un compost urbain sur la sclérotiniose du soja et la santé du solRousseau, Guillaume 12 April 2018 (has links)
Chez deux sols (loam argileux ou sableux), on a comparé l'effet de la monoculture de soja et de la rotation soja-maïs (2-3 ans de maïs puis 1-2 ans de soja), ainsi que l'effet d'un compost urbain et de la fertilisation minérale, sur la survie et la germination carpogénique des sclérotes du Sclerotinia sclerotiorum et sur la sclérotiniose du soja. Au site argileux, la rotation de 3-ans-de-maïs a réduit (effet suppressif) la gravité de la maladie par un rendement accru du soja et par la diminution du couvert de dicotylédones, alors que le compost a augmenté la maladie. L'azote était négativement corrélé à la survie des sclérotes sous fertilisation minérale. Au site sableux, l'interaction 3-ans-de-maïs x compost a réduit la maladie. La teneur en argile a favorisé la germination carpogénique et la gravité de sclérotiniose, alors qu'une stabilité structurale accrue et l'activité microbiologique étaient négativement corrélées à la germination. Cette étude approfondit les interactions entre pratiques culturales, santé du sol et couvert végétal, et contribue à mieux expliquer leurs effets propres et communs sur la sclérotiniose.
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Untersuchungen zur Schadwirkung von Sclerotinia sclerotiorum (Lib. de Bary) und Verticillium longisporum (comb. nov. Karapapa) in Winterraps (Brassica napus) / Investigations on the damage potential of Sclerotinia sclerotiorum (Lib. de Bary) and Verticillium longisporum (comb. nov. Karapapa) in winter oilseed rape (Brassica napus)Dunker, Sarah 02 February 2006 (has links)
No description available.
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ANÁLISE ESPACIAL E QUANTIFICAÇÃO DE INÓCULO DE MOFO BRANCO (Sclerotinia sclerotiorum (Lib) de Bary) NA CULTURA DA SOJA (Glycine max (L) Merril)Wutzki, Carlos Rafael 14 August 2017 (has links)
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Previous issue date: 2017-08-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O conhecimento da dinâmica espacial de doenças de plantas, aliado a quantificação de inóculo
e monitoramento das condições meteorológicas é de grande importância para a adoção de
estratégias de manejos adequados e com menor impacto ambiental. Sendo assim, os objetivos
deste trabalho de pesquisa foram caracterizar a distribuição, variabilidade espacial e possíveis
relações entre atributos referentes ao mofo branco e atributos de plantas de soja além de avaliar
técnicas de identificação e quantificação de ascósporos de Sclerotinia sclerotiorum durante o
florescimento da soja. Foram realizadas amostragens através de uma malha georreferenciada
em uma área de 12 hectares (ha) no município de Mauá-da-Serra-PR nas safras 2013/14 e
2014/15 e uma área de quatro hectares no município de Ponta Grossa-PR na safra 2015/16.
Foram utilizados quadrats com área útil de 7,2 m² para avaliação das seguintes variáveis:
escleródios presentes no solo, estande da cultura, incidência, índice de doença, rendimento,
escleródios produzidos na colheita, além da deposição do bioaerossol, partes de folha e flores
da soja como uso de Meio Semi-seletivo a Sclerotinia sclerotiorum (MSS) e Reação em cadeia
da polimerase quantitativa (qPCR), em 36 pontos de amostragem na área de Ponta Grossa-PR,
em três datas durante o florescimento da soja. Os dados foram analisados com uso de estatística
descritiva, ajuste de semivariogramas e matriz de correlação de Pearson. As condições
meteorológicas observadas nos três experimentos foram adequadas para o desenvolvimento da
cultura da soja e do mofo branco na soja. As variáveis referentes a cultura da soja apresentaram
coeficientes de variação baixos ou moderados e as variáveis referentes ao mofo branco
apresentaram coeficiente de variação muito elevados. Os ajustes dos semivariogramas
apresentaram diferenças nos três experimentos, com efeito pepita puro, ajuste linear, esférico e
exponencial. A variável escleródios do solo apresentou efeito pepita puro nos dois experimentos
em Mauá-da-Serra. Foram encontradas correlações significativas positivas entre a incidência
do mofo branco e a produção de escleródios na colheita, além de correlação negativa com o
rendimento nos três experimentos. A identificação de inóculo de mofo branco com incubação
em MSS mostrou-se a técnica com maior sensibilidade, mas demanda de até 15 dias para a
confirmação de S. sclerotiorum, tanto para bioaerossol, como flores e partes de folhas de soja.
Foi possível otimizar o protocolo de extração de DNA e ciclo de reação para qPCR, além de
gerar uma curva padrão com DNA oriundo de ascósporos de S. sclerotiorum, com ajuste ao
modelo linear (R²=0,99) e eficiência de 92,2%. O uso de qPCR mostrou-se promissor para
partes de folhas, sendo possível resultados em um dia de trabalho. / The knowledge of the spatial dynamics of plant diseases, allied with the quantification of
inoculum and monitoring of the meteorological conditions, is important for the adoption of
adequate management strategies and with less environmental impact. The aim of this work was
to characterize the distribution, spatial variability and possible relations between white mold
attributes and soybean plants attributes, as well as to evaluate techniques for identification and
quantification of ascospores of Sclerotinia sclerotiorum during soybean flowering. Samplings
were carried out through a georeferenced grid on a field of 12 hectares (ha) in the municipality
of Mauá-da-Serra-PR in the 2013/14 and 2014/15 crop seasons and, on a field of four hectares
in the municipality of Ponta Grossa-PR in the 2015/16 crop season. Quadrats with a useful area
of 7.2 m² were used to evaluate the following variables: sclerotia in the soil, crop stand,
incidence, severity, yield, sclerotia produced at harvest, as well as bioaerosol deposition,
soybean leaf parts and flowers on semi-selective medium to Sclerotinia sclerotiorum (MSS)
and quantitative polymerase chain reaction (qPCR), at 36 sampling points in the Ponta Grossa-
PR field, at three dates during soybean flowering. Data were analyzed using descriptive
statistics, semivariogram adjustment and Pearson correlation matrix. The meteorological
conditions observed in the three experiments were adequate for the development of soybean
crop and white mold disease. The variables related to soybean plants, showed low or moderate
coefficients of variation and the variables related to white mold showed a high coefficient of
variation. The semivariograms adjustments showed differences in the three experiments, with
pure nugget effect, linear, spherical and exponential adjustments. The variable sclerotia of soil
showed pure nugget effect on the two experiments in Mauá-da-Serra. Significant positive
correlations were found between the incidence of white mold and the production of sclerotia at
harvest, in addition to negative correlation to yield in the three experiments. The identification
of white mold inoculum with incubation on MSS was shown to be the most sensitive technique,
but takes up to 15 days for the confirmation of S. sclerotiorum pathogen for bioaerossol, flowers
and parts of soybean leaves. It was possible to optimize the protocol of DNA extraction and
reaction cycle for qPCR, besides generating a standard curve with DNA from ascospores of S.
sclerotiorum, adjusted to the linear model (R² =0, 99) and efficiency of 92.2%. The use of qPCR
showed promise results for leaf parts, being possible achieve concluding results in one working
day.
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Indução de resistência em feijoeiro (Phaseolus vulgaris) por acibenzolar-S-metil e Bacillus cereus: aspectos fisiológicos, bioquímicos e parâmetros de crescimento e produção\" / Resistance induced in bean plants (Phaseolus vulgaris) by acibenzolar-S-methyl and Bacillus cereus: physiological and biochemical aspects, growth and production parametersKuhn, Odair José 26 February 2007 (has links)
A indução de resistência envolve a ativação de mecanismos de defesa latentes existentes nas plantas em resposta ao tratamento com agentes bióticos ou abióticos. As plantas apresentam sistema de defesa induzível, com a finalidade de economizar energia. Desse modo, a resistência induzida em condições naturais representará custo apenas na presença do patógeno. Porém, plantas que investem seus recursos para se defenderem na ausência de patógenos arcarão com custos que refletirão na produtividade, uma vez que as alterações metabólicas que levam a resistência apresentam custo adaptativo associado, o qual pode pesar mais do que o benefício. O efeito negativo na produtividade ocorre principalmente onde indutores químicos são utilizados repetidas vezes ou em doses mais elevadas. Assim, em alguns casos podemos estar caminhando sobre uma estreita linha entre custo e benefício, onde a cura pode ser tão ruim quanto a própria doença. Neste trabalho foram conduzidos experimentos objetivando verificar alterações bioquímicas e fisiológicas, correlacionando-as com parâmetros de produção do feijoeiro entre a indução mediada por acibenzolar-S-metil (ASM), indutor químico, e, a mediada por Bacillus cereus, indutor biológico, antes da chegada do patógeno. Para tanto, foram avaliados plantas de feijão, induzidas por esses dois indutores e desafiadas com Xanthomonas axonopodis pv. phaseoli, para constatar a ocorrência do fenômeno da indução de resistência. Na ausência do patógeno, foram avaliados os parâmetros fisiológicos respiração e fotossíntese, determinada a atividade de enzimas envolvidas no processo de defesa como peroxidase, quitinase, β-1,3-glucanase, fenilalanina amônia-liase e polifenoloxidase e a atividade de enzimas envolvidas no catabolismo como proteases, a síntese de compostos do metabolismo secundário como fenóis totais e lignina, a síntese de compostos do metabolismo primário como proteínas e açúcares redutores. Também se avaliou o crescimento das plantas, a produtividade e parâmetros de produção e alguns parâmetros de qualidade dos grãos. Observou-se a ocorrência da indução de resistência em função da aplicação dos dois indutores utilizados, porém para o indutor ASM a indução de resistência estava associada a aumentos na atividade de peroxidase, quitinase, β-1,3-glucanase e proteases, aumento da síntese de lignina e redução no teor de fenóis, aumentos no teor de proteínas solúveis e de açúcares redutores nas folhas, redução do crescimento e da produtividade, aumento do teor de proteína dos grãos e redução do teor de amido nestes. Já o B. cereus apenas ocasionou aumento na atividade de peroxidase de forma atenuada e tendeu a aumentar a atividade de proteases, e reduzir o teor de proteínas nas folhas sem interferir no crescimento ou na produtividade, mas reduziu o teor de proteína dos grãos, mas aumentou o teor de amido nestes. Portanto, o indutor B. cereus , aparentemente alterou muito pouco o metabolismo do feijoeiro, sem interferir na produtividade e melhorando a qualidade da produção, enquanto que o indutor abiótico ASM alterou muito mais seu metabolismo, gerando um custo metabólico e redirecionando os fotoassimilados para investir em defesas, a custo da redução da produtividade. / The induction of systemic resistance involves the activation of latent resistance mechanisms in plants against pathogens in response to the treatment with biotic or abiotic agents. The plants present latent defense system that can be activated with the goal of saving energy. Thus, the induced resistance under natural conditions will represent cost only in the pathogen presence. In this way, plants that invest their resources to defend themselves in the absence of the pathogen will pay off with costs that will reflect in productivity, since the metabolic changes that led to resistance have associated fitness cost which could outweigh the benefit. The negative effects on plant productivity usually occur when chemical inducers are used repeatedly or in higher doses, mainly in the absence of the pathogen. Thus, we can say that in some cases we can be walking on a fine line between cost and benefit, where the cure may be as bad as the disease itself. In this work, experiments were carry out to verify biochemical and physiologic alterations, correlating them with production parameters of bean plants treated with acibenzolar-S-methyl (ASM), chemical inducer, or Bacillus cereus , biological inducer, before the pathogen arrival. Initially, bean plants were evaluated for induced resistance against Xanthomonas axonopodis pv. phaseoli when treated with the two inducers. In the absence of the pathogen, it was evaluated the physiological parameters respiration and photosynthesis and the activity of enzymes involved in the defense as peroxidase, chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase and polifenoloxidase and activity of enzymes involved in the catabolism as proteases, and the synthesis of compounds of the secondary metabolism as phenols and lignin, and the synthesis of compounds of the primary metabolism as proteins and sugars. The growth of the plants was evaluated as well as their productivity and production parameters. Some quality parameters of the grains were also evaluated. The occurrence of the resistance induced in the bean plants against the pathogens was observed for the two inducers. However, for the ASM the resistance induced was associated to increases in peroxidase, chitinase and β-1,3-glucanase activities, increase in the protease activity, increase in lignin synthesis and reduction in the phenol content, increase in soluble proteins and sugar content in the leaves, reduction of the growth and productivity, increasing the protein and reducing the starch content of the grains. The B. cereus only increased peroxidase activity in a lower way and showed a tendency to increase protease activity, and to reduce the protein content in the leaves without interfering in the growth or in the productivity, but it reduced the protein content and it increased the starch content of the grains. Therefore, the biotic inducer, B. cereus altered a minimum the metabolism of the bean plant, without interfering in the productivity and improving the quality of the production, while the abiotic inducer ASM altered its metabolism, generating a metabolic cost and consuming the plant photosyntathes to invest in defenses, causing a reduction in the productivity.
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Detecção de Sclerotinia sclerotiorum em meio Neon-S modificado em sementes de soja e feijão / Detection of sclerotinia sclerotiorum in modified NEON-S medium in soybean and common beans seedsSantos, Roberto Resende dos 24 February 2015 (has links)
The Neon-S method has been used for the detection of Sclerotinia sclerotiorum in soybean and
common beans since the agricultural year 2010. However, this method yields false positive
readings due to other fungi that change medium pH. Thus, this study evaluated the contribution
of increasing incubation period on the optimization of Neon-S reliability in different cultivars of
soybeans and common beans. Nine treatments were evaluated in randomized blocks design, as a
3x3 factorial, with three replications. The factors were three detection methods (paper roll, Neon-
S, and Neon S2) and three cultivars: naturally infected Pérola beans; naturally infected soybean
cultivar BRS Valiosa RR, and artificially inoculated soybean cultivar Nidera 7255 RR).
Inoculation of soybean Nidera 7255 RR was done by incubating the seeds for 72 h on PDA
where the fungus was previously grown for seven days at 25 ºC. The three methods were
compared, evaluating 400 seeds per replication, after incubation for seven days in Neon-S, for
15 days in Neon-S2, and for 30 days in paper roll, determining the presence of the fungus, and
that of sclerotia adhered to the seeds. Twenty seeds were used per plate for media Neon-S and
Neon-S2 (20 plates per replication), and 50 seeds per roll for the paper roll. Seeds were
incubated at 20 ºC in BDO chamber in darkness. The data were submitted to the analysis of
variance and the averages compared by the Tukey test at 5% probability. The interaction
between detection method and cultivar was significant at 1% probability, indicating that the best
method depends on the cultivar under study. Among the cultivars evaluated, artificially infected
soybean presented the greatest indices of pathogen infection. A comparison of seed lots analyzed
at the Plant Disease Clinic LAMIP proved greater sensibility of Neon-S in a total of 637 lots
evaluated from 2008 to 2012. In that period, the paper roll test resulted in 21.88% positive
samples, while in Neon-S 31.25% of them were positive. Another distinguishing factor among
the lots analyzed was the percentage of infected and, or, contaminated seeds, which varied from
one (0.25%) to five (1.25%). Therefore, detection of S. sclerotiorum by the Neon-S2 method can
be optimized by incubation for 15 days, considering that, in this case, the formation of sclerotia
near the infected seeds confirm the presence of the pathogen, avoiding false positive readings.
Neon-S2 method increased detection sensibility of S. sclerotiorum in seed lots analyzed in
comparison with the paper roll method; however, in comparison with Neon S method, despite its
greater average, no significant differences were observed. / O método de Neon-S tem sido utilizado para a detecção de Sclerotinia sclerotiorum em sementes
de soja e feijão a partir da safra de 2010. Porém, esse método possibilita a leitura de falsos
positivos devido ao aparecimento de fungos que também alteram o pH do meio. O objetivo deste
trabalho foi verificar se o aumento do período de incubação pode contribuir para otimizar a
confiabilidade do teste Neon-S em diferentes cultivares de soja e feijão. Foram avaliados nove
tratamentos em delineamento de blocos casualizados no esquema fatorial 3x3, com três
repetições, sendo três métodos de detecção: rolo de papel, Neon-S e Neon S2 e três cultivares:
Feijão Pérola infectados naturalmente; soja cultivar BRS Valiosa RR infectadas naturalmente e
soja cultivar Nidera 7255 RR inoculada artificialmente. Para a inoculação da soja Nidera 7255
RR, as sementes foram incubadas em meio de cultivo BDA por 72 h, após o cultivo do fungo por
sete dias na temperatura de 25 ºC. Os três métodos foram comparados, avaliando 400 sementes
por repetição, meio Neon-S com incubação de sete dias, Neon-S2 com incubação de quinze dias
e o rolo de papel por trinta dias, anotando-se a presença do fungo e a presença de escleródios
aderidos às sementes. No meio Neon-S e Neon-S2 foram utilizadas 20 sementes por placa (20
placas por repetição). No rolo de papel foram usadas 50 sementes por rolo. As sementes foram
incubadas 20 ºC em BOD, no escuro. Realizou-se a análise de variância dos dados e teste de
comparação de médias (Tukey 5%). A interação entre o método de detecção e a cultivar utilizada
foi significativo a 1% de probabilidade, indicando que o melhor método depende da cultivar
avaliada. Dentro das cultivares avaliadas, a soja infectada artificialmente foi a que apresentou os
maiores índices de infecção pelo patógeno. Usando os resultados de lotes de sementes,
comprovou-se a maior sensibilidade do Neon-S num montante de 637 lotes testados no período
de 2008 a 2012. Durante esse período, o teste de rolo apresentou 21,88% de amostras positivas,
enquanto que o Neon-S foi de 31,25%. Outro fator diferenciador em relação aos lotes analisados
foi a porcentagem de sementes contaminadas e ou infectadas, que variou de uma (0,25%) a cinco
(1,25%). Assim a detecção de S. sclerotiorum pelo método Neon-S2 pode ser otimizada com a
incubação por 15 dias, considerando que, neste caso, a formação de escleródios próximos às
sementes infectadas confirma a presença do patógeno e evita a leitura de falsos positivos. O
método Neon-S2 aumentou a sensibilidade de detecção de S. sclerotiorum em lotes de sementes
analisadas quando comparado ao método de rolo, porém, quando comparado com o método
Neon S, sua média foi maior, mas a diferença não foi significativa. / Mestre em Agronomia
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Indução de resistência em feijoeiro (Phaseolus vulgaris) por acibenzolar-S-metil e Bacillus cereus: aspectos fisiológicos, bioquímicos e parâmetros de crescimento e produção\" / Resistance induced in bean plants (Phaseolus vulgaris) by acibenzolar-S-methyl and Bacillus cereus: physiological and biochemical aspects, growth and production parametersOdair José Kuhn 26 February 2007 (has links)
A indução de resistência envolve a ativação de mecanismos de defesa latentes existentes nas plantas em resposta ao tratamento com agentes bióticos ou abióticos. As plantas apresentam sistema de defesa induzível, com a finalidade de economizar energia. Desse modo, a resistência induzida em condições naturais representará custo apenas na presença do patógeno. Porém, plantas que investem seus recursos para se defenderem na ausência de patógenos arcarão com custos que refletirão na produtividade, uma vez que as alterações metabólicas que levam a resistência apresentam custo adaptativo associado, o qual pode pesar mais do que o benefício. O efeito negativo na produtividade ocorre principalmente onde indutores químicos são utilizados repetidas vezes ou em doses mais elevadas. Assim, em alguns casos podemos estar caminhando sobre uma estreita linha entre custo e benefício, onde a cura pode ser tão ruim quanto a própria doença. Neste trabalho foram conduzidos experimentos objetivando verificar alterações bioquímicas e fisiológicas, correlacionando-as com parâmetros de produção do feijoeiro entre a indução mediada por acibenzolar-S-metil (ASM), indutor químico, e, a mediada por Bacillus cereus, indutor biológico, antes da chegada do patógeno. Para tanto, foram avaliados plantas de feijão, induzidas por esses dois indutores e desafiadas com Xanthomonas axonopodis pv. phaseoli, para constatar a ocorrência do fenômeno da indução de resistência. Na ausência do patógeno, foram avaliados os parâmetros fisiológicos respiração e fotossíntese, determinada a atividade de enzimas envolvidas no processo de defesa como peroxidase, quitinase, β-1,3-glucanase, fenilalanina amônia-liase e polifenoloxidase e a atividade de enzimas envolvidas no catabolismo como proteases, a síntese de compostos do metabolismo secundário como fenóis totais e lignina, a síntese de compostos do metabolismo primário como proteínas e açúcares redutores. Também se avaliou o crescimento das plantas, a produtividade e parâmetros de produção e alguns parâmetros de qualidade dos grãos. Observou-se a ocorrência da indução de resistência em função da aplicação dos dois indutores utilizados, porém para o indutor ASM a indução de resistência estava associada a aumentos na atividade de peroxidase, quitinase, β-1,3-glucanase e proteases, aumento da síntese de lignina e redução no teor de fenóis, aumentos no teor de proteínas solúveis e de açúcares redutores nas folhas, redução do crescimento e da produtividade, aumento do teor de proteína dos grãos e redução do teor de amido nestes. Já o B. cereus apenas ocasionou aumento na atividade de peroxidase de forma atenuada e tendeu a aumentar a atividade de proteases, e reduzir o teor de proteínas nas folhas sem interferir no crescimento ou na produtividade, mas reduziu o teor de proteína dos grãos, mas aumentou o teor de amido nestes. Portanto, o indutor B. cereus , aparentemente alterou muito pouco o metabolismo do feijoeiro, sem interferir na produtividade e melhorando a qualidade da produção, enquanto que o indutor abiótico ASM alterou muito mais seu metabolismo, gerando um custo metabólico e redirecionando os fotoassimilados para investir em defesas, a custo da redução da produtividade. / The induction of systemic resistance involves the activation of latent resistance mechanisms in plants against pathogens in response to the treatment with biotic or abiotic agents. The plants present latent defense system that can be activated with the goal of saving energy. Thus, the induced resistance under natural conditions will represent cost only in the pathogen presence. In this way, plants that invest their resources to defend themselves in the absence of the pathogen will pay off with costs that will reflect in productivity, since the metabolic changes that led to resistance have associated fitness cost which could outweigh the benefit. The negative effects on plant productivity usually occur when chemical inducers are used repeatedly or in higher doses, mainly in the absence of the pathogen. Thus, we can say that in some cases we can be walking on a fine line between cost and benefit, where the cure may be as bad as the disease itself. In this work, experiments were carry out to verify biochemical and physiologic alterations, correlating them with production parameters of bean plants treated with acibenzolar-S-methyl (ASM), chemical inducer, or Bacillus cereus , biological inducer, before the pathogen arrival. Initially, bean plants were evaluated for induced resistance against Xanthomonas axonopodis pv. phaseoli when treated with the two inducers. In the absence of the pathogen, it was evaluated the physiological parameters respiration and photosynthesis and the activity of enzymes involved in the defense as peroxidase, chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase and polifenoloxidase and activity of enzymes involved in the catabolism as proteases, and the synthesis of compounds of the secondary metabolism as phenols and lignin, and the synthesis of compounds of the primary metabolism as proteins and sugars. The growth of the plants was evaluated as well as their productivity and production parameters. Some quality parameters of the grains were also evaluated. The occurrence of the resistance induced in the bean plants against the pathogens was observed for the two inducers. However, for the ASM the resistance induced was associated to increases in peroxidase, chitinase and β-1,3-glucanase activities, increase in the protease activity, increase in lignin synthesis and reduction in the phenol content, increase in soluble proteins and sugar content in the leaves, reduction of the growth and productivity, increasing the protein and reducing the starch content of the grains. The B. cereus only increased peroxidase activity in a lower way and showed a tendency to increase protease activity, and to reduce the protein content in the leaves without interfering in the growth or in the productivity, but it reduced the protein content and it increased the starch content of the grains. Therefore, the biotic inducer, B. cereus altered a minimum the metabolism of the bean plant, without interfering in the productivity and improving the quality of the production, while the abiotic inducer ASM altered its metabolism, generating a metabolic cost and consuming the plant photosyntathes to invest in defenses, causing a reduction in the productivity.
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Management of Sclerotinia stem rot of soybean and diversity of Pythium irregulare in OhioHuzar Novakowiski, Jaqueline January 2017 (has links)
No description available.
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Agronomic approaches in yield and quality stability of high oleic sunflowers (Helianthus annuus L.) / Pflanzenbauliche Ansätze zur Ertrags- und Qualitätssicherung bei hochölsäurehaltigen (HO) Sonnenblumen (Helianthus annuus L.)Dilci, Burcin 23 October 2008 (has links)
No description available.
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Studies on Sclerotinia sclerotiorum (Sclerotinia stem rot) on soybeans.Visser, Dael Desiree. January 2007 (has links)
Soybeans, Glycine max, are an economically and strategically important crop in South
Africa (SA). In order to meet local demands, large imports of soybeans are required,
e.g., in the 2005/2006 soybean production period, 842 107 tonnes of oilcake were
imported. Due to an increase in soybean production throughout the world, diseases that
affect this crop have also increased in incidence and severity.
Sclerotinia sclerotiorum, the causal organism of sclerotinia stem rot (SSR), is an
important yield limiting disease of soybeans, as well as numerous other crops. The
pathogen was first reported in SA in 1979. However, it was only in 2002 that this fungus
was considered a major pathogen of soybeans in SA.
The research reported in this thesis was conducted to investigate the epidemiology of
S. sclerotiorum and examine numerous potential control methods for this pathogen, i.e.,
resistant cultivars, biocontrol, chemical control and seed treatments. A S. sclerotiorum
isolate was obtained from sunflowers in Delmas, Mpumulanga, SA, in the form of
sclerotia. This isolate was cultured and sent for identification and deposition in the Plant
Protection Research Institute collection. This isolate, in the form of mycelia, was used
for the duration of the study.
For epidemiology studies, the effect of temperature, leaf wetness duration (LWD) and
relative humidity (RH) were examined for their effect on rate of pathogen development.
Twenty four combinations of temperature (19°C, 22°C, 25°C and 28°C), LWD (24, 48
and 72 hr) and RH (85 and 95%) were investigated. No interaction between
temperature, LWD and RH was found. Temperature alone was the only factor that
affected disease development. At 22°C, the rate of pathogen development (0.45 per
unit per day) was significantly higher than all other temperatures, indicating that this
temperature is optimum for disease development.
Thirteen different soybean cultivars, i.e., LS6626RR, LS6710RR, LS666RR, LS555RR,
LS6514RR, LS678RR, Prima 2000, Pan 626, AG5601RR, AG5409RR, 95B33, 95B53
and 96B01B, commercially grown in SA were investigated for their reaction to
S. sclerotiorum. Prima 2000, 96B01B, 95B33 and AG5409RR were considered to be
the least susceptible as they showed a significantly low rate of pathogen development
(0.28, 0.28, 0.24, 0.23 per unit per day, respectively) and produced a significantly low
number of sclerotia (3.03, 3.42, 3.21, 2.38, respectively). LS6626R and LS666RR may
be considered most susceptible because of their significantly high rate of pathogen
development (0.45 and 0.42 per unit per day, respectively) and high sclerotia production
(8.16 and 7.50, respectively). Regression analysis showed a positive correlation
coefficient (R2=0.71) between rate of growth of the pathogen and number of sclerotia
produced, indicating that a higher rate is associated with a higher number of sclerotia.
In vitro dual culture bioassays were performed to identify the biocontrol mechanisms of
the biocontrol agents, EcoT® (a seed treatment) and Eco77® (a foliar treatment), against
hyphae and sclerotia of S. sclerotiorum. Ultrastructural studies revealed that
mycoparasitism is the probable mode of action as initial signs of hyphae of EcoT® and
Eco77® coiling around hyphae of S. sclerotiorum were observed. Surface colonization
of sclerotia by hyphae of EcoT® and Eco77® was also observed.
In vitro antagonism of EcoT® against S. sclerotiorum on soybean seed was performed to
determine pre-emergence and post-emergence disease. There was no significant
difference in percentage germination between seeds treated with EcoT® and plated with
the pathogen, untreated seeds and no S. sclerotiorum, and the control (i.e. no EcoT®
and no pathogen). However, percentage non infected seedlings from seeds not treated
with EcoT® was significantly lower, suggesting that EcoT® may be successfully used as
a seed treatment for the control of SSR. In vivo trials were performed to investigate the
effect of silicon (Si) alone, and in combination with Eco77®, on the effect of the rate of
disease development. Plants treated with Eco77® had a significantly lower rate of
disease development (0.19 per unit per day for plants treated with Eco77® and S.
sclerotiorum and 0.20 per unit per day for plants treated with Eco77®, S. sclerotiorum
and Si), compared to plants not treated with Eco77® (0.29 per unit per day for plants
treated with S. sclerotiorum and 0.30 per unit per day for plants treated with S.
sclerotiorum and Si), regardless of the application of Si. Similarly, plants treated with
Eco77® had a significantly lower number of sclerotia (0.46 for plants treated with Eco77®
and S. sclerotiorum and 0.91 for plants treated with Eco77®, S. sclerotiorum and Si),
compared to plants not treated with Eco77® (3.31 for plants treated with S. sclerotiorum
and 3.64 for plants treated with S. sclerotiorum and Si). The significantly lower rate of
disease development coupled with a significant reduction in sclerotia showed that
Eco77®, and not Si, was responsible for reducing the severity of SSR. A strong positive
correlation between rate of disease development and the number of sclerotia produced
(R2=0.79) was observed.
For the investigation of various fungicides for the control of S. sclerotiorum, in vitro trials
to determine the potential of three different fungicides at different rates, i.e., BAS 516
04F (133 g a.i. ha-1), BAS 516 04F (266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1) and
Sumisclex (760 g a.i. ha-1) were initially conducted. The control (non-amended PDA)
had a significantly higher area under mycelial growth curve (243.0) than all fungicides
tested. BAS 516 04F (at both concentrations) and BAS 512 06F completely inhibited
the mycelial growth of S. sclerotiorum. Sumisclex inhibited the fungus by 89.07%. For
in vivo trials, preventative treatments, i.e., BAS 516 04F (133 g a.i. ha-1), BAS 516 04F
(266 g a.i. ha-1), BAS 512 06F (380 g a.i. ha-1), curative treatment, i.e. Sumisclex (760 g
a.i. ha-1) and a combination preventative/curative treatment, i.e., BAS 512 06F (380 g
a.i. ha-1)/Sumisclex (570 g a.i. ha-1) were investigated. No significant difference in
disease severity index (DSI) was found between fungicide treatments and the inoculated
control. BAS 512 06F and BAS 512 06F/Sumisclex had significantly lower grain yields
(6.09 g and 5.96 g, respectively) compared to all other treatments. There was a positive
correlation coefficient (R2=0.76), between DSI and grain yield, indicating that a high DSI
is correlated with low grain yield.
Trials to evaluate the effect of commercially available and currently unregistered seed
treatments for the control of S. sclerotiorum on soybean seeds in vivo and in vitro were
performed. Seed germination tests were performed to determine if seed treatments had
any negative effects on seed germination in vitro. All seed treatments tested, i.e., BAS
516 03F (8, 16 and 32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100
kg-1 seed), Celest XL (100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10
ml a.i. 100 kg-1 seed), Benomyl (150 g a.i. 100 kg-1 seed), Captan (240 ml a.i. 100 kg-1
seed), Thiulin (180 g a.i. 100 kg-1 seed) and Anchor Red (300 ml a.i. 100 kg-1 seed),
showed no negative effect on seed germination. For in vivo trials, BAS 516 03F (16 and
32 ml a.i. 100 kg-1 seed), BAS 512 00F (7.5, 15 and 32 ml a.i. 100 kg-1 seed), Celest XL
(100, 125, 200 and 250 ml a.i. 100 kg-1 seed), Sumisclex (5 and 10 ml a.i. 100 kg-1
seed), Benomyl and Anchor Red had significantly similar percent germination and
percent seedling survival as the untreated/uninoculated control. These seed treatments
should be recommended for the control of S. sclerotiorum, as they protected seed
during germination and subsequent seedling development. BAS 516 03F (8 ml a.i. 100
kg-1 seed) should not be recommended for the control of SSR, as it gave the lowest
percent germination and percent seedling survival.
The results presented in this thesis have helped to identify optimal environmental
conditions for the development of S. sclerotiorum, which is important for the
development of forecasting models for disease control. The least and most susceptible
cultivars of those tested have been identified. Biocontrol using Eco77® as a foliar
application showed great potential.
The effect of Si needs to be further investigated, including the testing of more frequent
applications and higher concentrations. The fungicides tested in this research did not
show any potential for the control of SSR. However, the spray programme tested is for
the control of soybean rust (Phakopsora pachyrhizi), and was investigated for its
potential for the control of SSR. The spray programme, fungicide application and rating
scale needs to be modified, to determine the true potential of these fungicides for the
control of SSR. Numerous seed treatments have shown potential for the control of seed
infection by SSR. Due to difficulties in producing ascospores, which are the primary
source of inoculum for this pathogen in the field, all studies in this research were
conducted with mycelia and not ascospores. The production, collection and storage of
ascospores needs to be thoroughly investigated, and research conducted with
ascospores. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
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