Tissular localization of a bark lectin from Sambucus peruviana Kunth and its involvement in defense mechanisms

MARTINEZ ARRIAZU, M.E.; QUIROGA, E.N.; SAMPIETRO, D.A.; VATTUONE, M.A.

Tucumán (Argentina)

Congreso; XX Annual Meeting of Tucuman Biology Society; 2003

Tucuman Biology Society

Plants developed defense strategies against pathogens and herbivores. It was suggested that lectins, would be involved in plant or seed protection against predators. The aim of this work was the study of the effect of a lectin isolated from Sambucus peruviana bark on the in vitro activity of fungus degradative enzymes of polysaccharides of the cell wall and the tissular allocation of the lectin. Fungi (Pycnoporus sanguineus, Ganoderma applanatum, Lenzites elegans, Schizophylum commune) were cultivated in media with sucrose or pectin as carbon source. Pectinase and a-galacturonase activities were partially purified from the culture medium. The lectin inhibited the 24% of the polygalacturonase and 99% of the pectinase activities produced by P. sanguineus grown on sucrose and the 15 and 30% respectively, when it was grown on pectin. It was also evaluated the activity of other enzymes such as arabinofuranosidase and pectin liase. Immunolocalization assays of the lectin in transversal bark sections showed that it is located in the axial and radial parenchyma and in phloem but it was not detected in the xylem vessels in fungal cell wall degrading enzymes suggesting that the lectin would be involved in the defense mechanisms against predators.