RESUMO
From seeds of Nigella sativa L. (Ranunculaceae), an endemic plant of Uzbekistan, two novel defensins named Ns-D1 and Ns-D2, were isolated and sequenced. The peptides differ by a single amino acid residue and show high sequence similarity to Raphanus sativus L. defensins Rs-AFP1 and Rs-AFP2. The Ns-D1 and Ns-D2 defensins display strong although divergent antifungal activity towards a number of phytopathogenic fungi. High antifungal activity of N. sativa defensins makes them promising candidates for engineering pathogen-resistant plants.
Assuntos
Antibacterianos/química , Antifúngicos/química , Defensinas/química , Nigella sativa/química , Sementes/química , Sequência de Aminoácidos , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Antifúngicos/isolamento & purificação , Antifúngicos/farmacologia , Cromatografia por Troca Iônica , Defensinas/isolamento & purificação , Defensinas/farmacologia , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
The isolation and structure of a phytoalexin, malvone A (2-methyl-3-methoxy-5,6-dihydroxy-1,4-naphthoquinone) is reported. Malvone A formation is induced in Malva sylvestris L. by the plant pathogen Verticillium dahliae. In a turbimetric assay for toxicity to V. dahliae, it had an ED50 value of 24 microg/ml. The structure of malvone A was determined by MS and NMR spectroscopy, and by X-ray crystallographic analysis. The X-ray analysis showed water molecules were located in channels that run along the a-axis.
