Efeito fungitóxico de óleos essenciais sobre Phakopsora euvitis, agente causal da ferrugem da videira / Fungitoxic effect of essential oils on Phakopsora euvitis, causal agent of grape rust

O conhecimento sobre os efeitos indesejáveis do uso de fungicidas convencionais, associado à preocupação de órgãos reguladores e consumidores quanto à qualidade dos alimentos, tem estimulado a busca por novas alternativas para o controle de doenças de plantas. O objetivo deste trabalho foi avaliar, em laboratório e em campo, a atividade antifúngica de 16 óleos essenciais sobre Phakopsora euvitis , agente causal da ferrugem da videira. Foram utilizados os óleos essenciais de orégano, menta piperita, pimenta preta, nim, eucalipto globulus , citronela, canela, manjerona, alecrim, manjericão, camomila azul, cânfora branca, cravo, gengibre, tomilho branco e melaleuca. No laboratório foram realizados dois experimentos: no primeiro, foi avaliada a germinação de esporos, em meio ágar-água acrescido do óleo essencial, nas concentrações de 0,0, 0,1, 0,5, 1, 2 e 4% (v/v), e sobre este foi depositada a suspensão de esporos. No segundo experimento, aplicaram-se os óleos essenciais em folhas destacadas de videira, seguindo-se a inoculação dos esporos de P. euvitis , avaliando-se a germinação dos esporos. A partir dos dados obtidos foram calculadas as percentagens de inibições da germinação de esporos e a dose letal (DL90). Em plantas de videira no campo foi realizada uma aplicação dos óleos essenciais, na concentração de 1%, e avaliada a severidade da ferrugem, após 15 e 30 dias. As DL90 dos óleos essenciais variaram entre 0,39% (nim) e 3,9% (orégano). Os óleos essenciais mais eficientes sobre P. euvitis , em condições in vitro , foram os de camomila azul, citronela, eucalipto globulus , gengibre, nim e tomilho branco. Na aplicação realizada em campo todos os óleos essenciais reduziram significativamente a severidade da ferrugem, destacando-se os óleos essenciais de canela, citronela, nim e tomilho branco. Aspectos relacionados à fitotoxicidade necessitam ser elucidados. Os óleos essenciais avaliados apresentam potencial para serem utilizados no manejo da ferrugem da videira, contudo estudos complementares fazem-se necessários.(AU)

Knowledge about undesirable effects of conventional fungicides, and concern from consumers and Regulatory Agencies about food quality have encouraged the research on new alternatives for controlling plant diseases. The objective of this study was to evaluate the antifungal activity of 16 essential oils on Phakopsora euvitis , causal agent of grape rust in vitro and under field conditions. The essential oils tested were oregano, peppermint, black pepper, neem, eucalyptus globulus , citronella, cinnamon, marjoram, rosemary, basil, blue chamomile, white camphor, clove, ginger, tea tree and white thyme. In vitro , two experiments were carried: (i) evaluation of spores germination in water agar media amended with essential oil at 0 (control), 0.1, 0.5, 1, 2 and 4% (v/v). (ii) Evaluation of spores germination on detached leaves of vine previously treated with a solution of essential oils at 0, 0.1, 0.5, 1, 2 and 4%. The percentage of inhibition in the spores germination and LD90 values were calculated. Under field conditions, essential oils 1% (v/v) were sprayed on vine plants, and rust severity was evaluated twice, 15 and 30 days post application. In in vitro tests, the LD90 values ranged from 0.39 (neem) to 3.9% (oregano). The most efficient essential oils on Phakpsora euvitis were blue chamomile, citronella, eucalyptus globulus , ginger, neem and white thyme. Under field conditions, all essential oils reduced rust severity and among them, those from cinnamon, citronella, neem and white thyme showed the highest level of rust control. Our results show that the essential oils tested are effective for the management of grape rust. However, further studies on the phytotoxicity of these compounds are still required.(AU)

Germination of Bacillus anthracis spores:research advances / 军事医学

A spore is another life cycle form of Bacillus anthracis for resisting starvation.When conditions are favorable for growth, the dormant spore will germinate,go through outgrowth, and are ultimately converted back into a growing cell. As the first step back to vegetative growth, germination could be induced by nutrients and a variety of non-nutrient agents. Nutrient germinants trigger cation release and water absorption by binding to receptors in the spore′s inner membrane.Then the spore′s peptidoglycan cortex is hydrolyzed and the spore core rehydrates, which allows the resumption of spore metabo-lism and macromolecular synthesis.This paper reviews the nutrient germinant receptor and cortex lytic enzymes in the spore germination process of B.anthracis.

A unique and profound effect of MgO and ZnO nanoparticles on some plant pathogenic fungi.

The antifungal activity of zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles prepared by bio-safe method was evaluated for Alternaria alternate, Fusarium oxysporum, Rhizopus stolonifer and Mucor plumbeus. It was observed from the study that all the nanoparticles at different concentrations brought about significant inhibition in the germination of spores of Alternaria alternata, Fusarium oxysporum, Rhizopus stolonifer and Mucor plumbeus. However, the highest inhibition in the germination of all the test fungi was observed at higher concentrations followed by lower concentrations of nanoparticles. The nanoparticles of MgO at highest concentration was found most effective in reducing the spore germination followed by nanoparticles of ZnO at the same concentration.

Antifungal activity of extracts from Brazilian Cerrado plants on Colletotrichum gloeosporioides and Corynespora cassiicola / Atividade antifúngica de extratos de plantas do Cerrado brasileiro sobre Colletotrichum gloeosporioides e Corynespora cassiicola

This study aimed to determine the antifungal activity of leaf aqueous and hydroethanolic extracts of 10 plants from the Brazilian Cerrado on Colletotrichum gloeosporioides and Corynespora cassiicola. Antifungal activity was measured through the incorporation of each extract in a culture media or spore suspension, at 50 percent concentration relative to the volume, determining respectively the mycelial growth and the spore germination. Then, the percentages of mycelial growth inhibition and spore germination inhibition were obtained based on the comparison with the control. The extracts had a variable action on the phytopathogens, from mycelial growth stimulation for Aristolochia esperanzae and Byrsonima verbascifolia extracts to complete inhibition of mycelial growth and spore germination for Myracrodruon urundeuva and Lafoensia pacari extracts. M. urundeuva, L. pacari and Caryocar brasiliense leaf extracts had antifungal activity against Colletotrichum gloeosporioides and Corynespora cassiicola; the hydroethanolic extracts presented more antifungal activity than the aqueous extracts, and spore germination of both phytopathogens was more affected than their mycelial growth.

O objetivo deste trabalho foi determinar a atividade antifúngica de extratos aquosos e extratos hidroetanólicos de folhas de 10 plantas do Cerrado brasileiro sobre Colletotrichum gloeosporioides e Corynespora cassiicola. A determinação da atividade antifúngica foi realizada pela incorporação do extrato em meio de cultura ou na suspensão de esporos, na concentração de 50 por cento em relação ao volume, determinando-se, respectivamente, o crescimento micelial e a germinação de esporos. Em seguida, pela comparação com a testemunha, foram obtidas as percentagens de inibição do crescimento micelial e da germinação dos esporos. Foi constatado comportamento variável dos extratos sobre os fitopatógenos, desde o estímulo no crescimento micelial para os extratos de Aristolochia esperanzae e Byrsonima verbascifolia, até a inibição completa do crescimento micelial e dagerminação dos esporos para os extratos de Myracrodruon urundeuva e Lafoensia pacari. Extratos de folhas de L. pacari, de M. urundeuva e de Caryocar brasiliense apresentaram atividade antifúngica sobre Colletotrichum gloeosporioides e Corynespora cassiicola; os extratos hidroetanólicos proporcionaram mais atividade antifúngica que os extratos aquosos, e a germinação de esporos de ambos os fitopatógenos foi mais afetada que o crescimento micelial.

Antifungal Activity of Securinine against Some Plant Pathogenic Fungi

The alkaloid securinine was assessed against spore germination of some plant pathogenic and saprophytic fungi (Alternaria alternata, Alternaria brassicae, Alternaria brassicicola, Curvularia lunata, Curvularia maculans, Curvularia pallenscens, Colletotrichum musae, Colletotrichum sp., Erysiphe pisi, Helminthosporium echinoclova, Helminthosporium spiciferum, Heterosporium sp.). Spore germinations of all the tested fungi were inhibited. Alternaria brassicicola, C. lunata, C. pallenscens and H. spiciferum were highly sensitive as complete inhibition of spore germination was observed at very low concentrations (200 ppm).

Effect of 1-corydalmine,an Alkaloid Isolated from Corydalis chaerophylla Roots on Spore Germination of Some Fungi

1-Corydalmine,an alkaloid isolated from roots of Corydalis chaerophylla inhibited spore germination of some plant pathogenic as well as saprophytic fungi e.g. Alternaria brassicae, A. brassicicola, A. solani, Curvularia lunata, C. maculans, C. sp., C. pallscens, Erysiphe pisi, Fusarium udum, Helminthosporium species,H. penniseti and a Heterosporium species. 1-Corydalmine significantly inhibited spore germination of all the fungi at 100 to 1500 ppm. It was effective against all the fungi at 1500 ppm. C. lunata was highly sensitive to this chemical even at 250 ppm.

Antifungal Activity of Narceine Methyl Ester and Narceine Isolated from Corydalis longipes Against Some Phytopathogenic Fungi

Narceine methyl ester and narceine are potent alkaloids which were isolated from Corydalis longipes were found effective in vitro at very low concentration, i.e., 100~500 ppm against spore germination of some test plant pathogenic fungi (Alternaria solani, A. tagetica, Cercospora abelmoschi, Curvularia maculans, Erysiphe cichoracearum, E. pisi, Fusarium udum, Helminthosporium oryzae, H. penniseti, Ustilago cynodontis). Among the test, phytopathogens the spores of F. udum, C. maculans and H. penniseti were highly sensitive at 200 ppm. However, spores of E. pisi, A. solani and A. tagetica were less sensitive at low concentration followed by other test fungi. Most of the fungi showed zero or nearly zero percent spore germination at 400 and 500 ppm.

Effect of the Mixture of Two Plant Alkaloids Isolated from Corydalis longipes Against Balsam Powdery Mildew on Detached Leaves and Pea Powdery Mildew in Field

N-Methylhydrasteine hydroxylactam and 1-methoxyberberine chloride, both alkaloids, extracted from Corydalis longipes have been assayed for their activities against two powdery mildews. The spore germination of Erysiphe cichoracearum on detached leaf of balsam(Impatiens balsaminia) following pre- and post-inoculation treatments by their mixture has shown high efficacy against the pathogen at 100, 200 and 300 microg/ml. The mixture was also effective at both pre- and post-inoculation treatments at 500, 1000, 1500 microg/ml doses against E. pisi causing pea powdery mildew in pea(Pisum sativum) under field conditions. The significant efficacy of the mixture of two compounds against spore germination on detached leaves of balsam and also under field conditions in pea warrants its inclusion in trials against some other diseases under field conditions.

Inhibitory Effect of Two Alkaloids, (-)-Corydalmine and (-)-Isocorypalmine Isolated from Corydalis chaerophylla on Several Phytopathogenic Fungi

Medicinal plants play important roles in controlling plant diseases as one of the safest and ecofriendly methods. These plants have been used in the form of crude extracts as well as active principles in vitro and under field conditions to control plant diseases. Among the active principles, alkaloids have shown significant antifungal activity. We have investigated the effect of two alkaloids viz., (-)-corydahnine and (-)-isocorypahnine isolated from Corydalis chaerophylla, against spore germination of some plant pathogenic and saprophytic fungal spores. Significant inhibition of spore germination at 100 microg/ml was seen against Curvularia penniseti, Curvularia sp. and Colletotrichum gloeosporioides by (-)-corydahnine but (-)-isocorypalmine was also effective against fungi included in the experiment.

Effect of Ent-norsecurinine, an Alkaloid, on Spore Germination of Some Fungi

The inhibitory activity of ent-norsecurinine alkaloid was evaluated against spore germination of some plant pathogenic fungi (Curvularia maculans, Curvularia species, C. palliscens, Colletotrichum gloeosporioides, Colletotrichum species, Alternaria solani, A. brassicae, Fusarium udum, Helminthosporium echinoclova and H. penniseti). It inhibited spore germination of all the test fungi. C. maculans, C. species, and C. palliscens were the most sensitive as complete inhibition of spore germination was observed at 1000 ppm. A. solani was not inhibited by this chemical.

Antifungal Activity of Methanolic of Centella asiatica and Andrographis panicuiata

The antifungal activity of methanolic extracts of Centella asiatica and Andrographis paniculata leaves was observed against fourteen fungi, viz., Alternaria alternata, A. brassicae, A. brassicicola, A. solani, A. tenuissima, Cercospora blumae, Curvularia lunata, C. penniseti, and Drechslera monoceras, D. oryzae, D. turitica, Fusarium albizziae and F. udum. Different concentrations of the methanolic extract (1000, 2000, 3000, 5000, 7000, 10000ppm) were used. The effect of mixed leaf extract (1500 ppm of C. asiatica + 1500 ppm of A. paniculata) and its 1:2 ad 1:4 dilutions were also studied. The individual extracts of both the plants showed significant inhibitory effect on spore germination of all the fungi tested. F. udum, F. albizzae, D. oryzae, D. turtica, and D. monoceras were particularly sensitive to these extracts. In general, the extract of C. asiatica showed a higher inhibitory effect in all concentrations against all the fungi as compared to A. paniculata, except for A. brassicae A. solani, D. oryzae, D. penniseti and Curvularia sp. The inhibitory effect of extracts increased when they were used in combination with or without dilutions against A. brassicicola, A. solani A. brassicae, A. alternata, A. tenussima, C. blumae, C. lunata, C. penniseti and Curvularia species. Higher efficacy of active ingredient of these extracts under field condition is envisaged against plant pathogens.

Influences of Pesticides on the Growth and Development of the Biocontrol Strain Pochonia chlamydospora ZK7 / 微生物学通报

By using PDA plate and PDB shaking culture method, the effect of six chemical pesticides on the spore germination, plate inhibition and Biomass of the biological control strains Pochonia chlamydospora ZK7 for tobacco root-knot nematodes were measured. Results showed that strain ZK7 is resistant to six pesticides at lower concentration and the resistance level are different among different pesticides. Carbetamide and thiophos of them have the biggest resistance, next is phoxim-methyl and metaldehyde, the last is carbophenothion and aldoxycarb.

Sequential release of cellulose enzymes during germination of Trichoderma reesei spores.

The pattern of release of extracellular cellulase during the germination of Trichoderma reesei spores has been examined. The four enzymes namely, filter paper degrading enzyme, β-1,4 endoglucanase, β-glucosidase and xylanase appear sequentially in the culture broth during germination of the spores. The order of enzyme appearance is not altered by the type of carbon source in the germination medium. Measureable quantities of filter paper degrading enzyme is detected only after the outgrowth has occurred. A possible mechanism of spore germination and induction of the enzymes by insoluble cellulose is suggested.