RESUMO
Floricolous downy mildews (Peronospora, oomycetes) are a small, monophyletic group of mostly inconspicuous plant pathogens that induce symptoms exclusively on flowers. Characterization of this group of pathogens, and information about their biology, is particularly sparse. The recurrent presence of a disease causing flower malformation which, in turn, leads to high production losses of the medicinal herb Matricaria chamomilla in Serbia has enabled continuous experiments focusing on the pathogen and its biology. Peronospora radii was identified as the causal agent of the disease, and morphologically and molecularly characterized. Diseased chamomile flowers showed severe malformations of the disc and ray florets, including phyllody and secondary inflorescence formation, followed by the onset of downy mildew. Phylogeny, based on internal transcribed spacer and cox2, indicates clustering of the Serbian P. radii with other P. radii from chamomile although, in cox2 analyses, they formed a separate subcluster. Evidence pointing to systemic infection was provided through histological and molecular analyses, with related experiments validating the impact of soilborne and blossom infections. This study provides new findings in the biology of P. radii on chamomile, thus enabling the reconstruction of this floricolous Peronospora species' life cycle.
Assuntos
Camomila , Peronospora , Camomila/microbiologia , DNA Espaçador Ribossômico/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Genes Fúngicos/genética , Peronospora/classificação , Peronospora/genética , Peronospora/fisiologia , Filogenia , Doenças das Plantas/microbiologiaRESUMO
Methanolic extracts of flowers and leaves of Gentiana lutea L., together with the isolated compounds mangiferin, isogentisin and gentiopicrin, were used to investigate the antimicrobial activity of the plant. A variety of Gram-positive and Gram-negative bacteria as well as the yeast Candida albicans has been included in this study. Both extracts and isolated compounds showed antimicrobial activity with MIC values ranging from 0.12-0.31 mg/ml. Our study indicated that the synergistic activity of the pure compounds may be responsible for the good antimicrobial effect of the extracts. Quantification of the secondary metabolites was performed using HPLC.
Assuntos
Antibacterianos/isolamento & purificação , Candida albicans/efeitos dos fármacos , Flores/química , Gentiana , Extratos Vegetais/uso terapêutico , Folhas de Planta/química , Antibacterianos/farmacologia , Cromatografia Líquida de Alta Pressão , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Extratos Vegetais/isolamento & purificaçãoRESUMO
Xanthone-O-glycosides with 1,3,7,8-oxidation pattern and flavone isoorientin-3'-O-glucoside were isolated from the aerial parts of Gentiana utriculosa. Xanthone-C-glucoside lancerin was detected in Gentiana species for the first time. The distribution of these compounds within the section Calathianae is discussed.
