RESUMO

MAIN CONCLUSION: The biostimulant Hanseniaspora opuntiae regulates Arabidopsis thaliana root development and resistance to Botrytis cinerea. Beneficial microbes can increase plant nutrient accessibility and uptake, promote abiotic stress tolerance, and enhance disease resistance, while pathogenic microorganisms cause plant disease, affecting cellular homeostasis and leading to cell death in the most critical cases. Commonly, plants use specialized pattern recognition receptors to perceive beneficial or pathogen microorganisms. Although bacteria have been the most studied plant-associated beneficial microbes, the analysis of yeasts is receiving less attention. This study assessed the role of Hanseniaspora opuntiae, a fermentative yeast isolated from cacao musts, during Arabidopsis thaliana growth, development, and defense response to fungal pathogens. We evaluated the A. thaliana-H. opuntiae interaction using direct and indirect in vitro systems. Arabidopsis growth was significantly increased seven days post-inoculation with H. opuntiae during indirect interaction. Moreover, we observed that H. opuntiae cells had a strong auxin-like effect in A. thaliana root development during in vitro interaction. We show that 3-methyl-1-butanol and ethanol are the main volatile compounds produced by H. opuntiae. Subsequently, it was determined that A. thaliana plants inoculated with H. opuntiae have a long-lasting and systemic effect against Botrytis cinerea infection, but independently of auxin, ethylene, salicylic acid, or jasmonic acid pathways. Our results demonstrate that H. opuntiae is an important biostimulant that acts by regulating plant development and pathogen resistance through different hormone-related responses.

Assuntos

RESUMO

Plant food production is severely affected by fungi; to cope with this problem, farmers use synthetic fungicides. However, the need to reduce fungicide application has led to a search for alternatives, such as biostimulants. Rare-earth elements (REEs) are widely used as biostimulants, but their mode of action and their potential as an alternative to synthetic fungicides have not been fully studied. Here, the biostimulant effect of gadolinium (Gd) is explored using the plant-pathosystem Arabidopsis thaliana-Botrytis cinerea. We determine that Gd induces local, systemic, and long-lasting plant defense responses to B. cinerea, without affecting fungal development. The physiological changes induced by Gd have been related to its structural resemblance to calcium. However, our results show that the calcium-induced defense response is not sufficient to protect plants against B. cinerea, compared to Gd. Furthermore, a genome-wide transcriptomic analysis shows that Gd induces plant defenses and modifies early and late defense responses. However, the resistance to B. cinerea is dependent on JA/ET-induced responses. These data support the conclusion that Gd can be used as a biocontrol agent for B. cinerea. These results are a valuable tool to uncover the molecular mechanisms induced by REEs.

Assuntos

RESUMO

Standard area diagrams (SADs) are plant disease severity assessment aids demonstrated to improve the accuracy and reliability of visual estimates of severity. Knowledge of the sources of variation, including those specific to a lab such as raters, specific procedures followed including instruction, image analysis software, image viewing time, etc., that affect the outcome of development and validation of SADs can help improve standard operating practice of these assessment aids. As reproducibility has not previously been explored in development of SADs, we aimed to explore the overarching question of whether the lab in which the measurement and validation of a SAD was performed affected the outcome of the process. Two different labs (Lab 1 and Lab 2) measured severity on the individual diagrams in a SAD and validated them independently for severity of gray mold (caused by Botrytis cinerea) on Gerbera daisy. Severity measurements of the 30 test images were performed independently at the two labs as well. A different group of 18 raters at each lab assessed the test images first without, and secondly with SADs under independent instruction at both Lab 1 and 2. Results showed that actual severity on the SADs as measured at each lab varied by up to 5.18%. Furthermore, measurement of the test image actual values varied from 0 to up to 24.29%, depending on image. Whereas at Lab 1 an equivalence test indicated no significant improvement in any measure of agreement with use of the SADs, at Lab 2, scale shift, generalized bias, and agreement were significantly improved with use of the SADs (P ≤ 0.05). An analysis of variance indicated differences existed between labs, use of the SADs aid, and the interaction, depending on the agreement statistic. Based on an equivalence test, the interrater reliability was significantly (P ≤ 0.05) improved at both Lab 1 and Lab 2 as a result of using SADs as an aid to severity estimation. Gain in measures of agreement and reliability tended to be greatest for the least able raters at both Lab 1 and Lab 2. Absolute error was reduced at both labs when raters used SADs. The results confirm that SADs are a useful tool, but the results demonstrated that aspects of the development and validation process in different labs may affect the outcome.

Assuntos

RESUMO

ABSTRACT The aim of the present study is to evaluate the economic viability of tomato cultivation in a system of organic farming, and to compare it with the conventional farming system. The fixed and variable costs of both cultivation systems were calculated, as well as the costs of disease control with the application of alternative products and pesticides. The revenues were computed using commercial production and the direct sales price. The total cost per area was higher in the conventional system, while the cost per plant was greater in the organic system, since it used a lower plant population density. In the conventional system, 2.33 times more was spent on plant management, due to the fact that the number of sprayings was greater than that carried out in organic farming. We further find that companion planting with other species such as coriander, in addition to helping with the management of the main crop, is important for economic sustainability as it is an extra source of income. Considering the specificities of the two systems, the profitability of organic cultivation, even accounting for its lower productivity , could exceed that of conventional cultivation.

RESUMO

A produção de espécies reativas de oxigênio (EROs), a resposta de hipersensibilidade (HR) e a atividade das enzimas peroxidase de guaiacol, catalase, polifenoloxidase, B-1,3-glucanase e quitinase foram estudados em folhas de tomateiro resistente [CNPH 1287 (Solanum habrochaites syn. Lycopersicon hirsutum)] e suscetível [Santa Cruz Kada (S. lycopersicum syn. L. esculentum)] inoculadas com Alternaria solani. Essas folhas foram coletadas no momento da inoculação e às 4, 8, 12, 24, 48, 72, 96 e 120 h pós-inoculação. Os conídios germinaram igualmente na superfície foliar de ambos os genótipos sem orientação definida no crescimento dos tubos germinativos. A frequência de lesões causadas por A. solani foi menor no genótipo CNPH 1287 como consequência do menor número de apressórios formados nesse genótipo. O acúmulo de EROs foi observado em baixa frequência tanto no genótipo suscetível quanto no resistente. A HR foi observada nas células epidérmicas onde ocorreu penetração em ambos os genótipos. Os resultados deste trabalho indicam. Aumentos significativos na atividade de peroxidase de guaiacol, polifenoloxidase, B-1,3-glucanase e quitinase foram registrados no genótipo resistente. Estes resultados sugerem que, enquanto EROs e HR não parecem contribuir com a resistência de S. habrochaites frente a A. solani, as enzimas relacionadas à defesa cumprem um papel importante nas respostas de defesa deste genótipo.(AU)

The production of reactive oxygen species (ROS), hypersensitive response (HR), and the activity of the enzymes guaiacol peroxidase, catalase, polyphenol oxidase, B-1,3-glucanase and chitinase, were studied in leaves of resistant [CNPH 1287 (Solanum habrochaites syn. Lycopersicon hirsutum)] and susceptible [Santa Cruz Kada (S. lycopersicum syn. L. esculentum)] tomato genotypes inoculated with Alternaria solani. Leaves were collected at the time of inoculation and at 4, 8, 12, 24, 48, 72, 96 and 120 hours post inoculation. Conidia germination occurred equally onto the leaf surface in both genotypes and germination tubes grew without apparent orientation. Lesion frequency was lower in CNPH 1287, and it was the consequence of a lower number of appressoria formed in that genotype. ROS were observed in low frequency in both genotypes. HR was observed in penetrated epidermal host cells also in both genotypes. It seems that ROS and HR would not contribute to the resistance of S. habrochaites to A. solani in this study. The activity of guaiacol peroxidase, polyphenol oxidase, B-1,3-glucanase and chitinase was significantly increased in the resistant genotype. These results suggest that defense-related enzymes but no oxidative burst play a role in the defense response of S. habrochaites to A. solani.(AU)

Assuntos

RESUMO

A produção de espécies reativas de oxigênio (EROs), a resposta de hipersensibilidade (HR) e a atividade das enzimas peroxidase de guaiacol, catalase, polifenoloxidase, B-1,3-glucanase e quitinase foram estudados em folhas de tomateiro resistente [CNPH 1287 (Solanum habrochaites syn. Lycopersicon hirsutum)] e suscetível [Santa Cruz Kada (S. lycopersicum syn. L. esculentum)] inoculadas com Alternaria solani. Essas folhas foram coletadas no momento da inoculação e às 4, 8, 12, 24, 48, 72, 96 e 120 h pós-inoculação. Os conídios germinaram igualmente na superfície foliar de ambos os genótipos sem orientação definida no crescimento dos tubos germinativos. A frequência de lesões causadas por A. solani foi menor no genótipo CNPH 1287 como consequência do menor número de apressórios formados nesse genótipo. O acúmulo de EROs foi observado em baixa frequência tanto no genótipo suscetível quanto no resistente. A HR foi observada nas células epidérmicas onde ocorreu penetração em ambos os genótipos. Os resultados deste trabalho indicam. Aumentos significativos na atividade de peroxidase de guaiacol, polifenoloxidase, B-1,3-glucanase e quitinase foram registrados no genótipo resistente. Estes resultados sugerem que, enquanto EROs e HR não parecem contribuir com a resistência de S. habrochaites frente a A. solani, as enzimas relacionadas à defesa cumprem um papel importante nas respostas de defesa deste genótipo.

The production of reactive oxygen species (ROS), hypersensitive response (HR), and the activity of the enzymes guaiacol peroxidase, catalase, polyphenol oxidase, B-1,3-glucanase and chitinase, were studied in leaves of resistant [CNPH 1287 (Solanum habrochaites syn. Lycopersicon hirsutum)] and susceptible [Santa Cruz Kada (S. lycopersicum syn. L. esculentum)] tomato genotypes inoculated with Alternaria solani. Leaves were collected at the time of inoculation and at 4, 8, 12, 24, 48, 72, 96 and 120 hours post inoculation. Conidia germination occurred equally onto the leaf surface in both genotypes and germination tubes grew without apparent orientation. Lesion frequency was lower in CNPH 1287, and it was the consequence of a lower number of appressoria formed in that genotype. ROS were observed in low frequency in both genotypes. HR was observed in penetrated epidermal host cells also in both genotypes. It seems that ROS and HR would not contribute to the resistance of S. habrochaites to A. solani in this study. The activity of guaiacol peroxidase, polyphenol oxidase, B-1,3-glucanase and chitinase was significantly increased in the resistant genotype. These results suggest that defense-related enzymes but no oxidative burst play a role in the defense response of S. habrochaites to A. solani.

Assuntos

RESUMO

O oídio (Erysiphe diffusa) tornou-se uma das principais doenças que afeta a cultura da soja (Glycine max), podendo causar redução significativa no rendimento da cultura. Esse trabalho teve por objetivo avaliar o efeito dos extratos aquosos de Agaricus blazei, Lentinula edodes e Pycnoporus sanguineus no controle do oídio em casa-devegetação e na indução de fitoalexinas em cotilédones de soja. O delineamento experimental utilizado foi inteiramente casualizado com cinco repetições. Como controle utilizou-se fungicida (enxofre ­ 3g/L) e testemunha - sem aplicação. Os tratamentos utilizados foram: extratos aquosos de Agaricus blazei, Lentinula edodes e Pycnoporus sanguineus na concentração de 20 %v/v sendo estes aplicados aos 61 e 68 dias após a semeadura. Avaliou-se a incidência e severidade aos 59, 65, 69, 73 e 77 dias após a semeadura em todos os folíolos de cada planta. Com os dados da severidade, calculouse a área abaixo da curva de progresso da doença (AACPD). Para a incidência, detectou-se diferença significativa entre o fungicida e os demais tratamentos. Para severidade e AACPD, observou-se que os extratos diferiram da testemunha, sendo que L. edodes mostrou ser mais eficiente que os demais tratamentos. Para o bioensaio de fitoalexinas foi aplicado sobre cada cotilédone de soja uma alíquota de 75 µL de cada extrato aquoso nas concentrações de 1%, 2%, 4% e 10%. Após 20 horas, os mesmos foram transferidos para erlenmeyers contendo 15 mL de água destilada esterilizada e deixados em agitação por 1 h para extração da fitoalexina formada. A absorbância foi determinada a 285 nm em espectrofotômetro. Observou-se um maior acúmulo de fitoalexina nas maiores concentrações dos extratos aquosos.

The powdery mildew (Erysiphe diffusa) became one of the main diseases that effects soybean (Glycine max) crops. The aim was to evaluate the effect of Agaricus blazei, Lentinula edodes and Pycnoporus sanguineus aquous extracts on the control of powdery mildew in greenhouse and on the induction of phytoalexins in soybean cotyledons. The control treatments consisted of fungicide (Sulphur ­ 3 g/L) and control without application. The treatments were applied at 61 and 68 days after sowing (DAS). The incidence and severity was evaluated at 59, 65, 69, 73 and 77 DAS in all the folioles of each plant. With the severity values, the area under the disease progress curve (AUDPC) was estimated. To the incidence, a significative difference was detected between the fungicide and the other treatments. For severity and the AUDPC, the extracts and the fungicide differed from the control and L. edodes was the most efficient treatment. For the phytoalexins production was applied 75 mL to each soybean cotyledon of each aqueous extract at 1%, 2%, 4% and 10% concentrations. After 20 hours, they were transferred to erlenmayer flask containing 15 mL of sterile distilled water and remained stirring for 1 h for extraction of phytoalexin. The absorbance was measured at 285 nm in a spectrophotometer. The highest accumulation of the phytoalexins was observed on highests concentrations of the aqueous extracts.

Assuntos

RESUMO

O objetivo deste trabalho foi estabelecer relações entre condições ambientais, o número de urediniósporos de Phakopsora pachyrhizi e a severidade da ferrugem-asiática-da-soja. Para quantificar urediniósporos de P. pachyrhizi, coletores foram instalados em campos de soja, em Itambé e Mandaguari, PR. Avaliações de severidade foram realizadas e dados climáticos foram coletados nos dois locais. As variáveis elaboradas foram: número de dias com umidade favorável (>60%), número de dias com temperatura favorável (18 a 32º C), preciptação acumulada e urediniósporos coletados. Uma variável baseada no controle químico também foi elaborada. Correlações entre as variáveis foram estimadas. A análise de trilha foi empregada para desdobrar as correlações. Cerca de 76% da variação das relações de causa e efeito entre as variáveis foi explicada pela análise de trilha. O número de dias para efetuar o controle químico teve efeito direto sob a severidade. O número de dias com temperatura favorável e as precipitações tiveram efeito indireto na severidade, atuando via manutenção de condições favoráveis de umidade.

The objective of this work was to study the relationships among environmental conditions, airborne urediniospores of P. pachyrhizi and the Asian soybean rust (ASR) severity. To quantify airbone urediniospores, collectors were installed in soybean fields in Itambé and Mandaguari, PR. Severity assessments were conducted and climatic data were collected in the two locations. The variables elaborated were: number of days with favorable humidity (<60%), number of days with favorable temperature (18-32ºC), rainfall accumulated and urediniospores collected. A variable based on the chemical control was also created. Correlations between variables were estimated. Path analysis was performed for correlations. Path analysis explained about 76% of the relations of cause and effect among the variables. Number of days to the chemical control had direct effect on severity. Number of days with favorable temperature and rainfall had indirect effect on severity. This two variables provided favorable humidity conditions for ASR development.

Assuntos

RESUMO

O objetivo do trabalho foi estudar o efeito de doses e tempos de imersão em óleo de eucalipto (Eucalyptus globulus Labill.), utilizado na desinfecção das mudas, na produção e no controle de doenças da mandioquinha-salsa 'Amarela de Carandaí'. Foram avaliados nove tratamentos (0,45%/18"; 1,05%/18"; 0,45%/42"; 1,05%/42"; 0,75%/30"; 0,075%/18"; 1,425%/42"; 0,45%/3" e 1,05%/57"), no delineamento experimental de blocos casualizados, com quatro repetições. As mudas (rebentos) foram selecionadas, imersas nas soluções conforme os tratamentos e deixadas para secar. No dia do plantio, os rebentos foram cortados horizontalmente na parte basal e colocados no fundo dos sulcos, com o ápice para cima. A colheita foi realizada aos 229 dias após o plantio. Os maiores estandes iniciais e finais foram sob as doses de óleo menores que 1,0% e tempos de imersão variando entre 3" e 42". A interação dose de óleo de eucalipto e tempo de imersão das mudas influenciaram significativamente as produções de massa fresca de folhas (2,49 t ha-1, sob 0,30%/0,02"), rebentos (2,32 t ha-1, sob 0,38%/33,26") e raiz comercial (3,32 t ha-1, sob 0,44%/39,21" ) e as massas secas de coroa (0,38 t ha-1, sob 0,76%/36,57") e de raiz comercial (0,65 t ha-1, sob 0,20%/17,9" ). As mudas de mandioquinha-salsa devem ser desinfectadas com óleo de eucalipto em doses menores que 0,5% e com imersão na solução em torno de 40", para obter-se menor incidência e severidade de doenças foliares e maior produção de raízes comerciais

The aim of this work was to study the effect of eucalyptus oil (Eucalyptus globulus Labill.) which was used in disinfection of cuttings in different doses and periods of immersion, on yield and disease control of 'Amarela de Carandaí' Peruvian carrot. Nine treatments (0.45%/18"; 1.05%/18"; 0.45%/42"; 1.05%/42"; 0.75%/30"; 0.075%/18"; 1.425%/42"; 0.45%/3" and 1.05%/57") were evaluated in randomized block experimental design, with four replications. Before planting, cuttings (shoots) were selected, immersed in solutions as treatments and left to dry. The adherence of the oil was better using spreader-sticker. On planting day, shoots were cut horizontally at basal part and put at the bottom of the furrows, with their apices to upside. Harvest was done on 229 days after planting. The greatest initial and final stations were under doses of oil that were smaller than 1.0% and under periods of immersion that varied between 3" and 42". Dose of eucalyptus and period of immersion of cuttings interaction influenced significantly yields of fresh mass of leaves (2.49 t ha-1, under 0.30/0.02"), shoots (2.32 t ha-1, under 0.38%/33.26") and commercial root (3.32 t ha-1, under 0.44%/39.21") and dried masses of crowns (0.38 t ha-1, under 0.76/36.57") and of commercial root (0.65 t ha-1, under 0.20%/17.9"). It was concluded that Peruvian carrot cuttings must be disinfected with eucalyptus oil in doses smaller than 0.5% and with immersion around 40", in order to obtain the smallest incidence and severity of foliar diseases and the greatest yield of commercial roots.

Assuntos

Assuntos