Antifungal proteins from sorghum endosperm and their effects on fungal mycelium.

Three antifungal proteins identified in sorghum endosperm act on the
grain mould pathogen Fusarium moniliforme Sheldon causing inhibition of
growth (Sunitha Kumari and Chandrashekar J Sci Food Agric 64 (1994) 357-
364). Both morphological and biochemical changes in the fungal hyphae were
observed on treatment with the antifungal proteins. The 18 kDa antifungal
protein caused sloughing of cell wall polysacharides without much release of
cytoplasmic material as seen by a slight increase in absorbance at 280 and
265 nm, and by microscopic examination. The decrease in pH or rise in electrical
potential of the medium as the fungi respired was not altered by the presence of
the 18 kDa antifungal protein in the incubation mixture. The 26 and 30 kDa
protein fraction on the other hand caused leakage of cytoplasmic contents as
observed microscopically without releasing polysaccharides from the cell wall.
Addition of 26 and 30 kDa proteins to the incubation medium reduced the rate
of the rise in pH or fall in electrical potential of the medium. Immunofluorescent
microscopy indicated that the 18 and 26 kDa proteins bound to discrete areas of
the fungal hyphal walls whereas, the binding of the 30 kDa antifungal protein
was non-specific.