35 research outputs found
Nematodes Affecting Soybean and Sustainable Practices for Their Management
Plant‐parasitic nematodes are one of the limiting factors for soybean production worldwide. Overall, plant‐parasitic nematodes alone cause an estimated annual crop loss of $78 billion worldwide and an average crop yield loss of 10–15%. This imposes a challenge to sustainable production of food worldwide, since there has been increasing demand for food supply and food security. Unsustainable cropping production systems with monocultures, intensive use of soils and expansion of crops to newly opened areas have intensified problems associated with new pests and diseases. Thus, finding and applying sustainable methods to control diseases associated with soybean are in current need. Over hundred nematode species, comprising fifty genera, have been reported in association with soybean. Of these, the root‐knot nematode Meloidogyne spp., cyst nematode Heterodera glycines, lesion nematode Pratylenchus brachyurus and the reniform nematode Rotylenchulus reniformis are major nematode species limiting soybean production. Here, we report an up‐to‐date literature review on the biology, symptoms, damage and control methods used for these nematodes species. Additionally, unusual and emergent nematode species affecting soybean are discussed
Environment and slow-release fertilizer in the production of Euterpe precatoria seedlings
Euterpe precatoria Mart. has been demanded due to the functional characteristics of its fruits and, therefore, its planting has been encouraged. However, there is a lack of information about the seedling production system of this palm tree. Neither a favorable environment nor the amount of fertilizer in the substrate have been defined for the production of healthy and vigorous seedlings. This study aimed to evaluate the effect of environments and doses of a slow-release fertilizer on the production of E. precatoria seedlings. The experiment was conducted in a randomized block design, with three replications and ten plants per plot. The treatments were arranged in a 4 x 5 factorial scheme, with four environments (under shading levels of 20 %, 30 %, 50 % and 75 %) and five doses of a slow-release fertilizer (0.0 kg m-3, 2.5 kg m-3, 5.0 kg m-3, 7.5 kg m-3 and 10.0 kg m-3 of substrate). The seedling height; root collar diameter; number of leaves; leaf, shoot, root and total dry mass; and the Dickson quality index were analyzed. There were significant interactions between the shaded environments and slow-release fertilizer doses for all the analyzed variables. The 75 %-shaded environment yielded better quality seedlings. The slow-release fertilizer can be used to produce E. precatoria seedlings in environments under shading levels of 50 % and 75 %, being the 4.60 kg m-3 and 8 kg m-3 doses, respectively, the most recommended ones
Bactérias endofíticas associadas a Paspalum vaginatum Swartz com potencial para promoção de crescimento vegetal e biocontrole: Endophytic bacteria associated with Paspalum vaginatum Swartz with potential for plant growth promotion and biocontrol
Espécies de Paspalum são importantes constituintes nas pastagens nativas de regiões tropicais e subtropicais das Américas. Paspalum vaginatum é nativo de áreas litorâneas no Brasil e é amplamente utilizado em campos de golfe nos Estados Unidos devido sua robustez e tolerância a estresses abióticos como a seca, encharcamento e salinidade. Bactérias localizadas no interior dessa espécie vegetal (endofíticas) podem ser parcialmente responsáveis pela tolerância a essas condições extremas. O uso de bactérias capazes de promover o crescimento vegetal como inoculantes é uma estratégia ecologicamente correta para substituir os fertilizantes químicos e melhorar a produção vegetal. Este estudo objetivou isolar e avaliar o potencial de solubilização de fosfato inorgânico (SFI), fixação biológica de nitrogênio (FBN), produção de ácido 3-indolacético (AIA) e potencial antagônico contra fitopatógenos de bactérias endofíticas associadas a P. vaginatum. As bactérias foram isoladas de raízes e folhas de P. vaginatum e testadas in vitro para FBN, SFI, produção de AIA e antagonismo contra o fungo fitopatogênico Bipolaris sp.. Entre os 72 isolados bacterianos testados, 43 fixaram nitrogênio (59,7%), 28 solubilizam fosfato inorgânico (38,9%), 70 produziram AIA (97,2%), mesmo que em baixa quantidade, e 12 apresentaram potencial antagônico contra Bipolaris sp. (16,7%). As 24 bactérias com melhores resultados nos testes foram identificadas por sequenciamento do gene 16S rDNA. Os gêneros identificados foram Bacillus sp., Pantoea sp., Enterobacter sp., Agrobacterium sp., Pseudomonas sp., Staphylococcus sp. e Streptomyces sp.
Influência de genótipos de couve (Brassica oleracea L. var. acephala DC.) na biologia de Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae)
An in vitro model for dengue virus infection that exhibits human monocyte infection, multiple cytokine production and dexamethasone immunomodulation
Seroreactivity to new Mycobacterium leprae protein antigens in different leprosy-endemic regions in Brazil
Host resistance and identification of genes differentially expressed in the soybean-Phakopsora pachyrhizi interaction
A produção brasileira de soja corresponde a 25% da safra mundial. Entre os problemas fitossanitários, a ferrugem asiática causada pelo fungo Phakopsora pachyrhizi é considerada a doença de maior importância, em todas as áreas de cultivo no mundo. Todavia, são escassos estudos relativos à biologia do fungo e sua gama de hospedeiros. Assim, este trabalho teve por objetivo identificar genes da soja diferencialmente expressos na interação soja UFVS 2002 P. pachyrhizi, e avaliar 55 genótipos de feijão-caupi (Vigna unguiculata (L.) Walp), 55 genótipos de guandu (Cajanus cajan (L.) Millsp.) e 13 de feijão-comum (P. vulgaris L.) quanto à resistência ao isolado monopustular PPUFV01. Duas bibliotecas subtrativas enriquecidas para genes diferencialmente expressos em soja em reposta à P. pachyrhizi, aos 2 e 9 dias após a inoculação, foram construídas. Foram identificados ESTs com similaridade a genes de resposta de defesa, genes de resposta a estresses, genes relacionados ao metabolismo basal e genes com função desconhecida. A análise da expressão diferencial por RT-qPCR de 25 genes selecionados, mostrou que 14 foram induzidos em resposta à infecção pelo patógeno, entre estes os genes que codificam para as proteínas PR4, thioredoxina, quitinase 1, R14, calmodulina, catalase, hemeoxigenase e RD22; estudos funcionais deverão ser efetuados para confirmar o papel de cada um desses genes na interação. Quanto à análise da resistência de hospedeiros foram identificadas 5 tipos de reação nos genótipos avaliados, sendo observadas reação de imunidade e suscetibilidade, com a formação de urédias esporulantes, similar ao que ocorre em soja. De modo geral todos, os genótipos de caupi foram resistentes, não sendo identificado nenhum genótipo com lesão tipo TAN, indicativa de susceptibilidade. Em guandu foram identificados de genótipos imunes a genótipos completamente suscetíveis, com nível de esporulação semelhante ao observado em soja. Nenhum genótipo de feijão-comum apresentou reação de imunidade, sendo identificados genótipos resistentes e suscetíveis, com esporulação menor do que a observada em soja. O feijão-comum e o guandu podem constituir importantes reservatórios para manutenção do fungo no campo na ausência de plantas de soja como também constituem importantes fontes de resistência a P. pachyrhizi.The Brazilian soybean production accounts for 25% of the world production. The soybean asian rust caused by Phakopsora. pachyrhizi is one of the most important fungal disease of this crop. However, there are few studies available related to the biology of the fungus and its host range. Thus, this work aimed to identify soybean genes differentially expressed in the soybean-UFVS 2002 P. pachyrhizi interaction, and to evaluate the resistance of 55 genotypes of cowpea (Vigna unguiculata (L.) Walp), 55 of pigeon pea (Cajanus cajan (L.) Millsp.) and 13 of the common bean (P. vulgaris L.) to the isolate PPUFV01. Two subtractive libraries enriched for genes differentially expressed in soybean in response to P. pachyrhizi, at 2 and 9 days after inoculation, were built. ESTs were identified with similarity to defense response genes, stress response genes, basal metabolism- related genes and genes with unknown function. Analysis of differential expression by RT-qPCR of 25 genes selected showed that 14 were induced in response to infection by the pathogen, including genes that codes for proteins PR4, thioredoxin, quitinase 1, R14, calmodulin, catalase, hemeoxigenase and RD22; functional studies must be carried out to confirm and quantify the function of these genes in the interaction. Host resistance analyses identified 5 types of reaction in the genotypes evaluated, ranging from immunity to susceptibility reactions similar to what occurs in soybean. In general, all the cowpea genotypes were resistant, and it was not observed genotype with TAN type lesion, indicative of susceptibility. In pigeon pea, genotypes ranging from immune to completely susceptible were identified; the susceptible genotypes had sporulating level similar to what is observed in soybean. No common bean genotype presented immunity reaction, with resistant and susceptible genotypes being identified, although with lower than suscetiple soybean. Common bean and pigeon pea can be important reservoirs for fungus maintenance in the field in the absence of soybean plants as well as important alternative sources of resistance genes to P. pachyrhizi.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio
Fungicides effect on conidia germination of Claviceps africana in vitro
A cultura do sorgo não enfrentava problemas sérios de doenças nas condições de cultivo no Brasil, até o ano de 1995, quando se registrou a ocorrência da doença-açucarada, causada por Claviceps africana, que afeta as panículas e reduz a quantidade e a qualidade dos grãos; os conídios constituem a principal fonte de inóculo fúngico. Este trabalho teve como objetivo estudar o efeito dos fungicidas tebuconazole, propiconazole, triadimenol, triadimefon, flutriafol e mancozeb na inibição in vitro da germinação dos conídios. Os fungicidas mancozeb, triadimenol e propiconazole foram os mais eficientes na inibição da germinação dos conídios.The sorghum crop did not face serious problems with diseases in Brazil, until occurrence of sugary disease (sorghum ergot), caused by Claviceps africana, was recorded in 1995 in Brazilian sorghum fields. The pathogen infects panicles reducing the quantity and quality of the produced grains. Conidia are the main fungus inoculum. This work aimed to study the potential of fungicides tebuconazole, propiconazole, triadimenol, triadimefon, flutriafol and mancozeb in inhibiting conidia germination in vitro. The fungicides mancozeb, triadimenol and propiconazole were the most effective to inhibit the in vitro germination