The objective of this research was to examination the chemical compounds and antimicrobial activity of domesticated Origanum vulgare subsp. viride essential oils from Mashhad and Yazd, Iran. GC and GC-MS analysis revealed that the essential oils of Mashhad andYazd samples predominantly contain thymol (20.97-21.6 %), 4-terpineol (16.27-15.85 %), γ-terpinene (7.62-5.46 %), trans-sabinene hydrate (6.11-7.91 %) and p-cymene (4.27-5.69 %). The variations observed between the essential oil compositions were mostly uantitative but also qualitative. The inhibitory effects of the essential oils were tested against 10 hytopathogenic microorganisms, including Xanthomonas citri, Ralstonia solanacearum, Erwinia amylovora, Pectobacterium carotovorum, Xanthomonas oryzae bacteria and Bipolaris sorokiniana, Fusarium oxysporum, Drechslera oryzae, Alternaria alternata and Stemphylium sarciniforne fungi. The antimicrobial test results indicated that the essential oils had antibacterial and antifungal activities against all of the tested microorganisms. According to the width of the inhibition zone X. citri was the most sensitive bacterium to the essential oils with MIC (3.5 μgmL-1) and MBC (5 μgmL-1) in both samples. The most sensitive fungus was D. oryzae with 1 and 0.8 μgmL-1 in Mashhad and Yazd essential oil samples. Also the most susceptible fungi with MIC 2.1 μgmL-1 were B. sorokiniana in essential oil obtained from Mashhad and S. sarciniforne with MIC 2.2 μgmL-1 in the essential oil of Yazd’s sample. In conclusion, due to the antimicrobial activities of O. vulgare subsp. viride essential oil, the effectiveness of essential oils against serious plant pathogens is considerable. I

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