The potential application of Origanum dubium Boiss. essential oil as a seed protectant against bean and tomato seed-borne bacterial pathogens

Origanum dubium is a valuable wild oregano species of the natural flora of Antalya, Turkey. In this study, we extracted essential oil (EO) by hydro-distillation of the aerial parts of selected O. dubium chemotype with highest EO content, and analyzed by gas chromatography/mass spectrometry. Carvacrol was the primary component (85.9%) among 24 different compounds in the EO. The volatile test showed minimum inhibitory effect of the EO against Xanthomonas axonopodis pv. vesicatoria, Clavibacter michiganensis subsp. michiganensis, Xanthomonas axonopodis pv. phaseoli, Xanthomonas axonopodis pv. phaseoli var. fuscans, and Pseudomonas syringae pv. tomato, at 309, 303, 318, 254, and 901 µL/mL, respectively. A 1-hour treatment of bean and tomato seeds in the volatile phase of the EO effectively sterilized the seeds from bacterial pathogens without inhibiting their germination. To the best of our knowledge, this is the first study on the potential for the use of O. dubium EO as a seed protectant against bean and tomato seed-borne bacterial pathogens.