Maria Eugênia Silva Cruz

Atividade antifúngica e proteção do tomateiro por extratos de plantas medicinais

The present work aimed to evaluate, in vitro, the fungitoxicity of aqueous crude extracts (ACEs) of Achillea millefolium, Artemisia camphorata, Cymbopogon citratus and Rosmarinus officinalis to Alternaria solani and their protective effect on tomato plants under greenhouse conditions. To evaluate the antifungal activity of ACEs, they were incorporated into potato-dextrose-agar medium and the inhibition of mycelial growth, sporulation and conidia germination was evaluated. The protective effect in plants was evaluated by means of preventive spraying (72 hours before inoculation) with ACE, at concentrations of 10 and 20%, in the first two leaves. Disease severity was verified 15 days after inoculation. It was observed that ACEs did not inhibit mycelial growth, but they had significant effects on the reduction of germination and sporulation, especially the ACEs of A. camphorata, C. citratus and R. officinalis, at concentrations up to 20%. A reduction was observed in the number of lesions in relation to the control, in leaves above those treated, observing the systemic effect of the extracts. The extracts from the studied plants may be promising in the control of early blight on tomato plants.

Essential oils on postharvest control of Colletotrichum gloeosporioides in papaya fruit

Os subprodutos de plantas medicinais tem sido estudados como uma alternativa para o controle de doencas de plantas visando amenizar e/ou reduzir o uso abusivo de agrotoxicos, principalmente em condicoes pos-colheita. Assim, este trabalho teve como objetivo avaliar, in vitro e in vivo, o controle de Colletotrichum gloeosporioides, agente causal da antracnose do mamao em pos-colheita, por oleos essenciais (OEs) de Cymbopogon citratus, Eucalyptus citriodora, Mentha arvensis e Artemisia dracunculus. Para inibicao do crescimento micelial in vitro, os OEs foram incorporados ao BDA (Batata-dextrose-agar) tendo-se observado a inibicao total ou parcial do crescimento micelial e da esporulacao deste fitopatogeno, dependendo do oleo essencial utilizado. No ensaio in vivo utilizaram-se os OEs de C. citratus (1%) e E. citriodora (1%). A inoculacao com o fitopatogeno foi concomitante e 24 h apos os tratamentos alternativos, que foram: oleos essenciais de C. citratus e de E. citriodora (1%) e biomassa citrica (150 mL 100 L-1) (Ecolife®). Os parâmetros avaliados foram severidade da doenca, reducao da massa, diâmetro, comprimento final dos frutos, pH e a concentracao de solidos soluveis totais (oBrix). Pode-se observar que, no controle da doenca, os frutos tratados e imediatamente inoculados com o fitopatogenos apresentaram maior AACPD (Area Abaixo da Curva do Progresso da Doenca). Porem, frutos tratados e inoculados 24 h apos os tratamentos apresentaram maior controle da doenca, confirmando o potencial dos oleos essenciais testados no presente trabalho.

Fungitoxicidade, atividade elicitora de fitoalexinas e proteção de alface em sistema de cultivo orgânico contra Sclerotinia sclerotiorum pelo extrato de gengibre

Sclerotinia sclerotiorum is a soilborne fungus and causes white mold, sclerotinia cottony rot in lettuce (Lactuca sativa) and other crops. The control of this disease is very difficult, since that fungus produces resistance structures, the sclerodia. In the search of new methods for disease control, the plant extracts with therapeutical properties arise as a new option. The effect of aqueous crude extract (ACE) of ginger (Zingiber officinalis) was evaluated in vitro at concentrations of 1, 5, 10, 15, 20 and 25% on S. sclerotiorum mycelial growth and sclerodia production. The efficiency of ginger on the production of lettuce plants was also verified in plants and inoculated with the pathogen. Disease incidence, crop yield and peroxidase activity were analyzed in plant tissue. Water and the resistance inducer agent acibenzolar-S-methyl were used as control. Additionally, the ability of ACE in inducing accumulation of phytoalexins 3-deoxyanthocyanidin and glyceollin was evaluated in sorghum and soybean bioassays, respectively. The results showed the antimicrobial activity of ginger on the inhibition of mycelial growth and sclerodia production. In the lettuce crop, it was observed that the application of ginger mass on the soil close to plants basis increased of peroxidase activity and reduced disease incidence. The presence of elicitor compounds in the ACE was detected by the production of phytoalexins in sorghum and soybean, with dose-dependent responses. These results showed the potential of Z. officinalis on the control of S. sclerotiorum in lettuce that can occur by antimicrobial activity and defense mechanisms induction.

Contribuição ao estudo das atividades antifúngica e elicitora de fitoalexinas em sorgo e soja por eucalipto (Eucalyptus citriodora)

Secondary compounds found in medicinal plants play important role in plant-pathogen interactions by having direct antimicrobian effect on them or inducing the defense mechanisms on defense of other plants. To verify the fungi toxic effect of the eucalyptus on the micelial growth of Rhizoctonia solani, Sclerotium rolfsii, Phytophthora sp, Alternaria alternata and Colletotrichum sublineolum, the crude extract (CE) was incorporate to PDA and the essential oil (EO) and distributed in the surface of the middle with Drigalski loop. Germination of spores of C. sublineolum was also evaluated in the presence of different brackets of EO using two methodologies. In order to verify the induction phytoalexins sorghum mesocotyls were asperged with CE to 20% or then dived in suspensions of EO. For the gliceolin induction, 20 µL of CE were put in cotyledons soybean. The presence of fungitoxic compounds in EO and CE through the thin layer chromatography was also evaluated. The results evidenced inhibition of the fungus micelial growth for concentrations of CE above 20%. All of the aliquots of the oil inhibited micelial growth micelial fungi, except for R. solani whose inhibition happened for aliquots above 20µL. There was inhibition of 100% in conidia germination for all of the aliquots of EO tested in the first methodology. However, in the second methodology EO did not promote inhibition of conidia germination. It was observed the presence of one fraction fungitoxic in EO, and CE did not present fungitoxic fractions. There was the phytoalexins production just in sorghum mesocotyls treated with CE.

Caracterização parcial de frações obtidas de extratos de Cymbopogon nardus com atividade elicitora de fitoalexinas em sorgo e soja e efeito sobre Colletotrichum lagenarium

Medicinal plants present potential to control phytopathogens due to the direct effect or by the activation of defense mechanisms like phytoalexins. Then, the present work had the objective to verify the antifungal and elicitor effect of citronella (Cymbopogon nardus) obtained from methanolic and ethanolic extracts. It was studied the accumulation of phytoalexins in the mesocotyls of sorghum and in cotyledon of soybean, in response to application of fractions from crude extracts methanolic (EME) and ethanolic extracts (EET) of citronella. The EME and EET extracts were fractioned by gel filtration chromatography (CFG) and three fractions were obtained from the methanolic extract (FMI, FMII and FMIII), and two fractions from the ethanolic extract (FEI and FEII). The molecular weight for the FMI, FMII, FMIII, FEI and FEII were 69.29, 40.51, 18.72, 65.89 and 24.11 kDa, respectively. The fractions obtained from the CFG were used in a bioassay of germination of C. lagenarium spores and of induction of phytoalexins in the mesocotyls of sorghum and cotyledon of soybean. There was no significative effect of the fractions EME and EET on germination and appressorium formation by the pathogen. In the accumulation of phytoalexins in soybean cotyledons there was no significant effect of the fractions FMI, FMII, FMIII, FEI and FEII. However, it was detected a significative effect of fractions obtained by CFG on the production of phytoalexins in mesocotyls of sorghum. The highest accumulation of phytoalexin in mesocotyls of sorghum was obtained in the FMI and FMIII fractions, which differed significantly to the control. Based on the obtained results, it is possible to conclude that fractions partially purified obtained from EME of C. nardus present potential to induce phytoalexins in sorghum mesocotyls.

Fungitoxidade in vitro de extratos vegetais sobre Exserohilum turcicum (Pass) Leonard & Suggs

Helminthosporiose is caused by the fungus Exserohilum turcicum and represents one of the main diseases in popcorn grown in Brazil. Due to its characteristics, such as plant size, planting area extension and economic profitability, the use of genetic resistance and chemical control has constituted the main procedure against such disease. The use of pesticides in agriculture has resulted in risks to the human health and frequent damages to the environment. Thus, the fungitoxic effect of plant extracts of Achillea millefolium (yarrow), Cymbopogon citratus (lemon grass), Artemisia camphorata (camphor) and Rosmarinus officinalis (rosemary) on the mycelial growth of E. turcicum was evaluated by using two culture media (PDA - potato dextrose agar, and LCH - lactose-casein hydrolysate) in order to set alternative methods for controlling helminthosporiose. Rosemary and camphor extracts led to higher mycelial growth inhibition in both culture media, whereas yarrow and lemon grass extracts stimulated mycelial growth in LCH medium.

Efeito dos compostos naturais bioativos na conservação pós-colheita de frutos de mangueira cv. Tommy Atkins

A antracnose causa severos danos na pos-colheita de manga. Como o controle quimico tem demonstrado desvantagens, o potencial uso de oleos essenciais para o controle de fitopatogenos tem sido uma alternativa. Neste trabalho, objetvou-se avaliar a eficacia de produtos alternativos no controle da antracnose e na conservacao de mangas (Mangifera indica) cv. Tommy Atkins tratado com bicarbonato de sodio diluido em agua destilada, na concentracao de 3% (v/v), via imersao. Como tratamento, foram utilizados os oleos essenciais de Origanum majorana, Citrus sinensis, Cymbopogon citratus e Eucalyptus citriodora, via fumigacao, na dosagem de 1000 μL e agua destilada via fumigacao; todos por 3 minutos. Frutos da Unidade CEASA-Maringa/PR, selecionados, pesados em balanca semianalitica, desinfetados em imersao por 3 minutos em solucao de hipoclorito de sodio a 0,5% (v/v); foram submetidos aos tratamentos, permanecendo sob condicoes ambientes (26 ± 2oC e UR 90 ± 5%). Exceto o tratamento com Citrus sinensis, que proporcionou um pH maior do que a testemunha, diferindo significativamente dos demais tratamentos que elevaram a variavel. A reducao da acidez em todos os tratamentos e aumentos dos solidos soluveis totais nos frutos, sendo que o tratamento com bicarbonato de sodio proporcionou 14,42 oBrix. O numero de frutos com antracnose foi menor no tratamento com Citrus sinensis e este diferiu dos demais comprovando o efeito de especies do genero Citrus como antifungicos. O uso de oleos essenciais como o de Citrus sinensis controlou a antracnose e manteve a qualidade dos frutos.

Control del moho azul en poscosecha de manzana con productos naturales

espanolEl uso de los extractos vegetales con actividad antimicrobiana para controlar enfermedades en pre o poscosecha es una alternativa promisoria frente al uso de fungicidas sinteticos. El objetivo de este estudio fue evaluar el efecto de extractos vegetales y aceites esenciales en manzanas infectadas naturalmente con Penicillium spp., agente causal del moho azul. Se sumergieron manzanas en extractos de citricos y de neem (Azadirachta indica) en concentraciones de 0,5 y 1,0% (v/v) y se almacenaron a 25 °C y 90% de humedad relativa. Despues de 21 dias se midio incidencia y severidad de la enfermedad. Tambien se evaluo el efecto de los aceites esenciales de Thymus vulgaris, Origanum vulgaris, Mentha piperita y Melaleuca alternifolia por fumigacion. La fruta se almaceno a 25±2 °C y 90±5% de humedad relativa durante 21 dias. Frutos tratados con agua destilada esteril constituyeron el tratamiento control. Los frutos sin tratar presentaron los valores mas altos de incidencia (100%) y severidad (99,98%) de moho azul, asi como el menor porcentaje de control (4,56%). Todos los tratamientos mostraron efecto antifungico de Penicillium spp, sin embargo, los extractos citricos y de A. indica en la concentracion de 1,0% proporcionaron los mayores niveles de control de la enfermedad (99,57% y 98,33%, respectivamente). Los frutos tratados con aceites esenciales mostraron menor incidencia, menor severidad y mayor control de la enfermedad. Se ha demostrado que el extracto y aceites esenciales estudiados tienen actividad antifungica y potencial para uso en poscosecha como una alternativa al control quimico. EnglishPlant extracts for the control of plant disease are emerging as promising alternatives to the use of synthetic fungicides. The objective of this work was to study the effect of plant extracts and essential oils on naturally infected apple fruits with Penicillium spp. causal agent of blue mold. Apple fruits were immersed in citric and Azadirachta indica extracts at concentrations of 0.5 and 1.0% (v/v), stored at room temperature (25 °C and 90% RH) and analyzed at 21 days after the application of the treatments. Evaluated also the effect of fumigation of apple fruits with essential oils of Thymus vulgaris, Origanum vulgaris, Mentha piperita and Melaleuca alternifolia. Treated fruits were stored at 25±2 °C and 90±5% relative humidity for 20 days. Treated fruit with distilled water constituted the group controls. The higher values of incidence (100%), severity (99.98%) and the lowest percentage of disease control (4.56%) were observed in apple fruits treated with distilled water (group control). All treatments exhibited inhibitory effect on Penicillium spp. in apple fruits, however, A. indica and citric extracts, at concentrations of 1.0%, had a disease control of98.33% and 99.57%, respectively. There were no significant differences between the oils applied; except between these and the control. However, the treatments with essential oils were that exhibited the least incidence, severity and control of the disease. The results showed that essential oils showed good results, above 98.1% of control of blue mold disease in postharvest. It was demonstrated that extracts the different concentration and essential oils have antifungal activities and that they have a potential use as an alternative control in relation to chemical methods.