Autofluorescent substances in root-knots induced by Meloidogyne incognita on Daucus carota L.

Localization of lignin, cutin, subednand cellulose was studied by fluorescence microscopy. The walls of degenerated syncytia, their adjacent tissues, all the necrotic cells especially those lining the nematode cavity and elements of normal and reaction xylem stained positive for lignin. All these lignified walls autofluoresced bright greenish-white, a characteristic of lignin. In necrotic patches, the cell contents autofluoresced white; when stained with Sudan dyes it confirmed the presence of suberin. The outer tangential walls of peripheral cells of healthy roots and galls of carrot autofluoresced for cutin and was histochemically confirmed. The parenchyma cell walls in the gall and healthy roots stained for cellulose and autofluoresced faintly.