A natural cyclic peptide valinomycin enhances plant innate immunity

SUMMARY Various natural compounds as alternative agents for the chemical management of plant diseases have long been proposed. Valinomycin, a Streptomyces -derived cyclic peptide, acts as an antifungal agent against several plant pathogenic fungi, including Botrytis cinerea . Here, we report the novel function of valinomycin, plant immune-boosting. Valinomycin potentiates pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) in Arabidopsis , leading to enhanced resistance against bacterial speck disease locally and systemically. Moreover, this plant immune-boosting activity of valinomycin is associated with plant hormonal signaling. Thus, we propose that valinomycin harbors potential as a biocontrol agent suppressing complex pathogen infections, such as bacteria and fungi.