Hordenine is responsible for plant defense response through jasmonate-dependent defense pathway

•Hordenine is a phenethylamine alkaloid found in barley.•Hordenine application suppressed grape downy mildew and strawberry anthracnose.•Hordenine has no effect on mycelial growth of phytopathogenic fungi.•Hordenine induces plant defense response through the jasmonate-dependent defense pathway.

Organic agriculture does not rely on synthetic chemical fungicides. An alternative pest management strategy to chemical fungicides is the use of bioactive natural compounds. Hordenine [4-(2-dimethylaminoethyl)] is a phenethylamine alkaloid found in barley. Although hordenine has various pharmacological effects, including antibiotic activity against microorganisms, no studies have been carried out to investigate the inhibitory effects of hordenine on phytopathogenic fungal infection in host plants. Both grape downy mildew and strawberry anthracnose were suppressed by hordenine treatment. Hordenine had no effect on mycelial growth of phytopathogenic fungi, whereas plant defense response through the jasmonate-dependent defense pathway was enhanced in hordenine-treated plants. The concern over environmental pollution has led to the introduction of new pesticides, including bioactive natural compound based pesticide. Hordenine may be used in organic agriculture as an innovative elicitor of plant defense response to downy mildew and anthracnose.