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Buckwheat Antifungal Protein with Biocontrol Potential To Inhibit Fungal (Botrytis cinerea) Infection of Cherry Tomato

Wang, Caicheng, Yuan, Susu, Zhang, Weiwei, Ng, Tzibun, Ye, Xiujuan
Journal of agricultural and food chemistry 2019 v.67 no.24 pp. 6748-6756
Botrytis cinerea, Fagopyrum esculentum, acid tolerance, ammonium sulfate, antifungal properties, biological control, buckwheat, calcium, cherry tomatoes, chloroform, chromatography, cymoxanil, ethanol, fruits, fungi, gels, ions, iron, isopropyl alcohol, leaves, magnesium, mancozeb, manganese, membrane permeability, membrane potential, methanol, mitochondrial membrane, mycelium, pH, peptides, potassium, seed extracts, spore germination, thermal stability
A 11 kDa antifungal protein FEAP was purified from buckwheat (Fagopyrum esculentum) seed extract with a procedure involving (NH₄)₂SO₄ precipitation and chromatography on SP-Sepharose, Affi-gel blue gel, Mono S, and Superdex peptide. Its N-terminal sequence was AQXGAQGGGAT, resembling those of buckwheat peptides Fα-AMP1 and Fα-AMP2. FEAP exhibited thermostability (20–100 °C) and acid resistance (pH 1–5). Its antifungal activity was retained in the presence of 10–150 mmol/L of K⁺, Mn²⁺, or Fe³⁺ ions, 10–50 mmol/L of Ca²⁺ or Mg²⁺ ions, and 50% methanol, 50% ethanol, 50% isopropanol, or 50% chloroform. Its half-maximal inhibitory concentrations toward spore germination and mycelial growth in Botrytis cinerea were 79.9 and 236.7 μg/mL, respectively. Its antifungal activity was superior to the fungicide cymoxanil mancozeb (248.1 μg/mL). FEAP prevented B. cinerea from infecting excised leaves, intact leaves, and isolated fruits of cherry tomato. Its mechanism involved induction of an increase in cell membrane permeability and a decrease in mitochondrial membrane potential.