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Effects of wild plants essential oils on the growth of Phytophthra cinnamomi and Castanea sativa

Sousa, Maria João; Martins, Fátima; Belo, Hélio; Choupina, Altino; Martins, Anabela
Fonte: Sociedade Portuguesa de Fitopatologia Publicador: Sociedade Portuguesa de Fitopatologia
Tipo: Conferência ou Objeto de Conferência
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Wild plant essential oil effects on the growth control of Phytophthora cinnamomi and Castanea sativa M. João Sousa1, Fátima Martins1, Hélio Belo1, Altino Choupina1, 2 and Anabela Martins1 1Instituto Politécnico de Bragança, Escola Superior Agrária, Campus de Santa Apolónia, Apartado 1172, 5301-854 Bragança, Portugal 2CIMO- Centro de Investigação de Montanha, Campus de Santa Apolónia, Apartado 1172, 5301-854 Bragança, Portugal Corresponding author: joaos@ipb.pt In regions that have chestnut as the main economic resource such as in Bragança, a region in the North of Portugal, plant diseases caused by Phytophthora cinnamomi namely the chestnut ink disease are the reason for major economic losses. The prospect of an active natural product agent has a great importance, especially if this product comes from a spontaneous plant, common in this region. The essential oils are natural compounds with bactericide, fungicide and allelopathic effects, and these characteristics can be a very interesting tool to control the development of the pathogenic agents and prevent infections cause by P. cinnamomi. The essential oils were tested in different concentrations from 100% to 2% dilutions (in 70% ethanol), on P. cinnamomi mycelium after 1...

Papel do alcalóide braquicerina na resposta ao estresse por radiação ultravioleta e dano mecânico em Psychotria brachyceras Müll Arg

Porto, Diogo Denardi
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
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As plantas superiores sintetizam uma ampla variedade de compostos, denominados classicamente metabólitos secundários, que as ajudam a se adaptar ao seu ambiente. Um subconjunto de metabólitos secundários são os alcalóides. Essas substâncias nitrogenadas de baixo peso molecular desempenham funções variadas nas plantas, podendo apresentar propriedades antibióticas, repelentes de herbívoros ou alelopáticas. O alcalóide monoterpeno indólico braquicerina, de estrutura inédita, foi extraído da planta arbustiva Psychotria brachyceras (Rubiaceae). Esse composto revelou ação específica como antiinflamatório em testes de quimiotaxia, possuindo, portanto, potencial valor farmacológico. Trabalhos anteriores revelaram que a molécula possui significativas propriedades antioxidantes e antimutagênicas, e que a concentração foliar desse alcalóide é induzida por dano mecânico e radiação ultravioleta (UV). Neste trabalho, demonstramos os resultados de uma série de experimentos desenvolvidos com o objetivo de entender o papel de braquicerina em P. brachyceras frente a esses estresses. Uma parte dos experimentos foi desenvolvida paralelamente com amostras de Psychotria carthagenensis da mesma região, que não acumula alcalóides e é mais sensível a UV do que P. brachyceras...

Oscillations in continuous culture populations of Streptococcus pneumoniae: population dynamics and the evolution of clonal suicide

Cornejo, Omar E.; Rozen, Daniel E.; May, Robert M.; Levin, Bruce R.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
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Agents that kill or induce suicide in the organisms that produce them or other individuals of the same genotype are intriguing puzzles for ecologists and evolutionary biologists. When those organisms are pathogenic bacteria, these suicidal toxins have the added appeal as candidates for the development of narrow spectrum antibiotics to kill the pathogens that produce them. We show that when clinical as well as laboratory strains of Streptococcus pneumoniae are maintained in continuous culture (chemostats), their densities oscillate by as much as five orders of magnitude with an apparently constant period. This dynamic, which is unanticipated for single clones of bacteria in chemostats, can be attributed to population-wide die-offs and recoveries. Using a combination of mathematical models and experiments with S. pneumoniae, we present evidence that these die-offs can be attributed to the autocatalytic production of a toxin that lyses or induces autolysis in members of the clone that produces it. This toxin, which our evidence indicates is a protein, appears to be novel; S. pneumoniae genetic constructs knocked out for lytA and other genes coding for known candidates for this agent oscillate in chemostat culture. Since this toxin lyses different strains of S. pneumoniae as well as other closely related species of Streptococcus...

Macroalgal terpenes function as allelopathic agents against reef corals

Rasher, Douglas B.; Stout, E. Paige; Engel, Sebastian; Kubanek, Julia; Hay, Mark E.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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During recent decades, many tropical reefs have transitioned from coral to macroalgal dominance. These community shifts increase the frequency of algal–coral interactions and may suppress coral recovery following both anthropogenic and natural disturbance. However, the extent to which macroalgae damage corals directly, the mechanisms involved, and the species specificity of algal–coral interactions remain uncertain. Here, we conducted field experiments demonstrating that numerous macroalgae directly damage corals by transfer of hydrophobic allelochemicals present on algal surfaces. These hydrophobic compounds caused bleaching, decreased photosynthesis, and occasionally death of corals in 79% of the 24 interactions assayed (three corals and eight algae). Coral damage generally was limited to sites of algal contact, but algae were unaffected by contact with corals. Artificial mimics for shading and abrasion produced no impact on corals, and effects of hydrophobic surface extracts from macroalgae paralleled effects of whole algae; both findings suggest that local effects are generated by allelochemical rather than physical mechanisms. Rankings of macroalgae from most to least allelopathic were similar across the three coral genera tested. However...

Manejo de plantas daninhas da cultura do arroz irrigado atrav??s de extratos alelop??ticos e agentes biol??gicos; Weed management of rice culture by allelopathic extracts and biological agents

BRUNES, Andr?? Pich
Fonte: Universidade Federal de Pelotas; Agronomia; Programa de P??s-gradua????o em Ci??ncia e Tecnologia de Sementes; UFPel; BR Publicador: Universidade Federal de Pelotas; Agronomia; Programa de P??s-gradua????o em Ci??ncia e Tecnologia de Sementes; UFPel; BR
Tipo: Dissertação Formato: application/pdf
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The objective of this study was to evaluate the allelopathic potential of aqueous extract of leaves of different rice cultivars in germination and seed vigor of weeds Digitaria, Aeschynomene and red rice and search the mycoflora of S. montevidensis in order to identify species of pathogenic fungi with the potential to act as bioherbicide and verify their specificity as to plants of irrigated rice. The first experiment was conducted in a completely randomized design with four replications in a factorial design, where the first factor tested of fresh leaves of rice cultivars (BRS Quer??ncia, Irga 424, Roxinho and Cica 07) and factor B concentrations of the extract compared (0, 25, 50, 75 and 100%). Evaluations of germination, first count of germination, velocity of germination, shoot length and root, dry mass of shoot and root. In the second experiment, the experimental design was completely randomized with five replications and the treatments arranged in a factorial design where the first factor was composed of two species of fungi (Fusarium semitectum and Fusarium oxyosporum), previously isolated from lesions found in plants collected during phase of suvery in the region of Pelotas paddy and factor B compared six levels of Spore concentration (0...

Oxidation of plant allelochemicals by phytophagous sucking insects / by Debrah F. Lorraine.

Lorraine, Debrah F.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 76281 bytes; application/pdf
Publicado em //1995 EN
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Phytophagous sucking insects, aphids in particular, are common pests of plants. These insects secrete salivary enzymes into their food material. One plant defence mechanism is the induction and/or accumulation of deterrent phytochemicals. In the present study, a model enzyme system was chosen to mimic the oxidative activity of insect saliva. Isolation and sructural identification of the products of plant allelochemicals was achieved for several substrates. Insects were also exposed to individual plant chemicals in feeding "choice" tests. Preliminary examinations suggest that plants containing increased levels of phenolic allelochemicals show correlated increases in resistance to attack by aphids.; Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1996; Addendum in pocket.; Biblography: leaves 162-173.; v, 177, [5] leaves : ill. ; 30 cm.; Title page, contents and abstract only. The complete thesis in print form is available from the University Library.

Initial in vitro evaluations of antibacterial activities of glucosinolate enzymatic hydrolysis products against plant pathogenic bacteria

Aires, A.; Mota, V.R.; Saavedra, M.J.; Monteiro, A.A.; Simões, M.; Rosa, E.A.S.; Bennett, R.N.
Fonte: The Society of Applied Microbiology Publicador: The Society of Applied Microbiology
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
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Aims: The aim of the study was to evaluate the in vitro antibacterial effects of glucosinolate hydrolysis products (GHP) against plant pathogenic micro-organisms namely Agrobacterium tumefaciens, Erwinia chrysanthemi, Pseudomonas cichorii, Pseudomonas tomato, Xanthomonas campestris and Xanthomonas juglandis. Methods and Results: Using a disc diffusion assay, seven different doses of 10 GHP were tested against each bacteria. The results showed that the isothiocyanates were potent antibacterials, whilst the other GHP were much less efficient. Moreover, the antibacterial effects were dose-dependent, increasing with the dose applied; 2-phenylethylisothiocyanate and sulforaphane showed the strongest inhibitory effects. The overall results show a great potential for using the isothiocyanates as an alternative tool to control undesired bacterial growth in plants. Conclusions: Glucosinolate hydrolysis products and more specifically the isothiocyanates: benzylisothiocyanate, 2-phenylethylisothiocyanate, the isothiocyanate Mix and sulforaphane, were effective phytochemicals against the in vitro growth of the phytopathogenic bacteria. The antibacterial activity exhibited by these phytochemicals reinforces their potential as alternatives to the traditional chemical control of phytopathogenic bacteria. Significance and Impact of the Study: This current in vitro study is the first providing comparative data on GHP as potential control agents for plant pathogenic bacteria. However...

Atividade alelopática, antioxidante e antimicrobiana de plantas com uso popular antimalárico

Ferrari, Ana Paula
Fonte: Pato Branco Publicador: Pato Branco
Tipo: Dissertação de Mestrado
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The aim of this study was to analyze the influence of different concentrations of crude ethanol extracts (EET) and dichloromethanic (EDC) of antimalarial medicinal species Bidens pilosa L. (beggartick), Phyllanthus niruri L. (shatter stone), Petiveria alliacea L. (guinea) and Senna hirsuta L. (sicklepod) on germination (GER), mean germination time (TMG), mean speed of germination (VMG), radicle (RAD) and hypocotyls (HIP) of Lactuca sativa L. (lettuce) and Ipomoea grandifolia (Dammer) O'Donel (rope-glory). The experimental design was completely randomized, distributed in a factorial (species antimalarial vs. extractor vs. concentration). Bioassays were performed with four replicates of 25 seeds for germination tests, and 10 pre-germinated seeds for the growth bioassays. Germinated seeds were counted daily for obtaining the TMG and VMG while GER, DAR and HIP were measured after 144 hours of application of the extracts. In parallel to the study of allelopathic activity aimed also to examine the antioxidant and antimicrobial activities of EET and EDC of four malarial species used in bioassays, as well as the species Quassia amara L. (quássia amarga). Analyses antioxidants were performed through three different methodologies, namely: scavenging of ABTS•+...

Residues of Citrus sinensis (L.) Osbeck as agents that cause a change in antioxidant defense in plants

Nunes, Patrícia Mayra Pavan; Silva, Cristiane Bezerra da; Paula, Cristiane da Silva; Smolarek, Fernanda Ferreira; Zeviani, Walmes Marques; Chaves, Suelen Cristina; Lorini, Fernando; Dias, Josiane de Fátima Gaspari; Miguel, Obdulio Gomes; Zanin, Sandra M
Fonte: Universidade de São Paulo. Faculdade de Ciências Farmacêuticas Publicador: Universidade de São Paulo. Faculdade de Ciências Farmacêuticas
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 01/06/2015 ENG
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This work aimed to verify the allelopathic potential of the extract of;Citrus; seeds, for the purpose of adding a sustainable value to the fruit seeds toward their use as industrial residues. The extract was obtained with a Soxhlet apparatus by using hexane, chloroform, and methanol as solvents. The hexane extract of the;Citrus; seeds primarily consisted of linoleic acid (36.6%), followed by α-linoleic acid (25.3%), oleic acid (17.8%), palmitic acid (9.7%), and estearic acid (3.3%). The analysis results indicate that the oil is similar to those used in the cosmetics and food industries and has an economic value from its industrial application. In addition, the use of the oil causes changes in the oxidant balance, germination, and growth of plants.; ;Este trabalho teve como objetivo verificar o potencial alelopático do extrato de sementes de ;Citrus;, com o objetivo de agregar valor sustentável para a semente de frutas para a sua utilização como resíduo industrial. O extrato foi obtido com aparelho de Soxhlet, utilizando hexano, clorofórmio e metanol como solventes. O extrato hexânico das sementes de ;Citrus; constituiu principalmente por ácido linoleico (36,6%), seguido por ácido α-linoleico (25,3%), ácido oleico (17,8%)...

Lipophilic constituents and some biological activities of hexanic extracts from Zaluzania montagnifolia, (SCH. BIP.) SCH. BIP. (Asteraceae)

Villa-Ruano,Nemesio; Pacheco-Hernández,Yesenia; Lozoya-Gloria,Edmundo; Rubio-Rosas,Efraín; Ruiz-González,Nancy; Martínez-Orea,Yuriana; Cruz-Duran,Ramiro; Ramirez-Garcia,S. Alberto; Ramón-Canúl,L. Guadalupe
Fonte: Colegio de Postgraduados Publicador: Colegio de Postgraduados
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
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Zaluzania montagnifolia, an antidiabetic and abortive shrub 1 to 3 m high, grows actively in xeric scrublands in some states of México. Zulazanins and some flavonoids are the foremost constituents of the polar extracts in this species; however, there is no available information about the lipophilic compounds from non-polar extracts. The objective of this study was to describe the gas chromatography-mass spectrometry (GC-MS) profile of hexanic preparations, exclusivelly with dissolve lipophilic molecules, in order to sustain the empirical uses and the new biological activities reported in this study for the plant. These preparations were obtained from flowers, leaves and roots of Z. montagnifolia which were collected in Oaxaca, México, in October 2011. In addition to the chemical study, antibacterial, allelopathic and antioxidant properties of the hexanic extracts were determined. The chemical profile revealed two majoritarian ent-kaurane diterpenes. According to the relative endogenous levels, grandiflorenic acid (35.5 %) and ent-kaurenoic acid (28.3 %) were the most abundant natural molecules in aerial and underground structures of the plant, and more than 50 different volatile organic compounds (VOC's) were identified according to their mass spectra and retention index. Antibacterial tests were carried out by the broth microdilution method in combination with hexanic extracts and conventional antibiotics as reference standards. The analyisi of results reveal potent inhibitory on Escherichia coli TOP10 F' (MIC=49.2 µg mL-1) and DH5α (MIC= 32.4 µg mL-1) strains as well as for Agrobacterium tumefaciens LBA 4404 (MIC=30.4 µg mL-1) strain. Allelopathic properties were determined using the lettuce seed system...