ANTIFUNGAL PROTEINS FROM SORGHUM ENDOSPERM AND THEIR EFFECTS ON FUNGAL MYCELIUM

Three antifungal proteins identified in sorghum endosperm act on the g rain mould pathogen Fusarium moniliforme Sheldon causing inhibition of growth (Sunitha Kumari and Chandrashekar J Sci Food Agric 64 (1994) 3 57-364). Both morphological and biochemical changes in the fungal hyph ae were observed on treatment with the antifungal proteins. The 18 kDa antifungal protein caused sloughing of cell wall polysacharides witho ut much release of cytoplasmic material as seen by a slight increase i n absorbance at 280 and 265 nm, and by microscopic examination. The de crease in pH or rise in electrical potential of the medium as the fung i respired was not altered by the presence of the 18 kDa antifungal pr otein in the incubation mixture. The 26 and 30 kDa protein fraction on the other hand caused leakage of cytoplasmic contents as observed mic roscopically without releasing polysaccharides from the cell wall. Add ition of 26 and 30 kDa proteins to the incubation medium reduced the r ate of the rise in pH or fall in electrical potential of the medium. I mmunofluorescent microscopy indicated that the 18 and 26 kDa proteins bound to discrete areas of the fungal hyphal walls whereas, the bindin g of the 30 kDa antifungal protein was non-specific.