Chemical Composition and Antifungal Activity of Zanthoxylum armatum Fruit Essential Oil against Phytophthora capsici

Pathogenic plant oomycetes cause devastating damage to fruits and vegetables worldwide. Plant essential oils (EOs) are known to be promising candidates for the development of fungicides. In this study, we isolated twelve EOs fromTetradium ruticarpum,Tetradium daniellii,Tetradium fraxinifolium,Zanthoxylum armatum,Ruta graveolens, andCitrus medicaleaves and fruits. We then investigated their chemical composition and antifungal activity against phytopathogenic oomycetes. Our results demonstrated thatZ. armatumfruit essential oil (ZFO) in particular substantially inhibited the mycelial growth ofPhytophthora capsici. Similarly, ZFO also strongly suppressed spore production and germination ofP. capsici, and the application of ZFO significantly reduced disease symptoms caused byP. capsiciin pepper. Furthermore, results from microscopic and biochemical studies indicated that ZFO damaged the ultrastructure and destroyed the membrane integrity ofP. capsici, leading to the leakage of the cellular contents and ultimately causing cell death. It was concluded that ZFO could enhance the activities of defense-related enzymes in pepper fruits, which may also be responsible for the inhibition of phytophthora disease. Moreover, linalool andD-limonene were proven to be the primary effective components of ZFO. Our results collectively indicate that ZFO could be a potential candidate for the management of disease caused byP. capsici.Keywords:Phytophthora capsici;antifungal activity;Zanthoxylum armatumfruit essential oil;action mechanism