Purification of a lectin-like antifungal protein from the medicinal herb, Withania somnifera

A 30 KDa monomeric acidic lectin-like protein was purified from the leaves of an important medicinal herb, Withania somnifera (L.) Dunal (Solanaceae), by a series of gel filtration and affinity chromatography methods. The inhibitory concentration of the protein ranged from 7 microg to 11 microg against major phytopathogens under in vitro conditions. The peptide sequence showed similarity to concanavalin A like lectin from Canavalia ensiformis and caused distinct cell wall adhesion of the protein treated hyphae under SEM. Further, the antifungal activity of the protein was compared with standard lectins like concanavalin A, phytohemagglutinin and wheat germ agglutinin.