HISTOCHEMICAL OBSERVATION OF HALO ON EPIDERMAL CELL WALL OF BARLEY LEAVES ATTACKED BY ERYSIPHE GRAMINIS HORDEI

Histochemical characters of the halo on the epidermal cell wall of barley leaves attacked by Erysiphe graminis hordei were investigated with light microscope. The area corresponding to the halo showed reduced intensity of stain reactions for cuticle, pectin and cellulose, especially at the penetration point. From the several histochemical reactions, it was concluded that reducing substances with aldehyde groups (such as hexose), pentoses and possibly uronic acids occur in the halo. According to these results, it can be concluded that the halo is caused by the degeneration of the epidermal cell wall by the fungal enzymes. © 1969 Dr. W. Junk N.V.