The effects of plant derived compounds on fusarium graminearum proteome.

Fusarium graminearum causes significant crop losses on wheat and other cereals and affects yield quality due to accumulation of mycotoxins. Several phenolic compounds are involved in the mechanism of plant disease resistance, having possibly also an effect on fungal growth and mycotoxin biosynthesis during the infection process. Five natural and natural-like compounds were selected, based on modeling and docking studies on the tri5 crystal from F. sporotrichioides and on physiological tests leading to a reduction in toxin synthesis by the fungus in vitro. Their effects on the proteome and the phenotype of a pure F. graminearum culture were investigated. Two time points were compared, corresponding to the peak of expression of genes involved in tricothecene B synthesis and to the toxin peak in in vitro cultures. A 2-D Fluorescence Difference Gel Electrophoresis approach combined with Matrix-assisted laser desorption/ionization time-of-flight mass spectrometer identification led to the detection of 526 differentially abundant spots; 319 resulted in single protein species. All identified protein species were classified for their putative localization within the cell and their biological function. The comparison of the proteomic profiles shaded light on some metabolic changes occurring in the interaction of the fungus with each compound during the two monitored stages of toxin production. Inhibition of toxin synthesis by the tested compounds is, at least partially, due to different mechanisms (some being specific to a given compound), including membrane damage, upstream regulation of secondary metabolite pathways and metabolic shifts.