The antifungal mechanism of potato glycoalkaloids was studied using a
sensitive species, Fusarium solani. The effects of potato glycoalkaloid
extract on the ultrastructure, membrane permeability, and contents of
reducing sugar, soluble sugar, soluble protein, and mycelial fat of F.
solani were determined. Potato glycoalkaloids significantly affected F.
solani mycelial morphology, resulting in bubbly mycelial cell walls,
incomplete outer layer, discontinuous cell membrane, disorganized
structures of mitochondria and other organelles, and visible leakage of
cell contents. Investigation of material metabolism indicated that
potato glycoalkaloids disrupted selective permeability of mycelial cell
membranes; caused massive exudation of internal lipids, proteins, and
carbohydrates; hindered hydrolysis of reducing sugar; affected nutrient
absorption and utilization; and inhibited decomposition metabolism of
mycelia. Thus, potato glycoalkaloids altered the morphology of fungal
mycelia, destroyed cell membrane structure, increased mycelial cell
membrane permeability, and caused cell contents leakage, resulting in
effective inhibition of growth and metabolism of plant pathogenic fungi
and so could decrease the occurrence of plant disease.