Toxicity of twenty-two plant essential oils against pathogenic bacteria of vegetables and mushrooms

Abstract

ASBTRACT Toxicity of twenty-two essential oils to three bacterial pathogens in different horticultural systems: Xanthomonas campestris pv. phaseoli (causing blight of bean), Clavibacter michiganensis subsp. michiganensis (bacterial wilt and canker of tomato), and Pseudomonas tolaasii (causal agent of bacterial brown blotch on cultivated mushrooms) was tested. Control of bacterial diseases is very difficult due to antibiotic resistance and ineffectiveness of chemical products, to that essential oils offer a promising alternative. Minimal inhibitory and bactericidal concentrations are determined by applying a single drop of oil onto the inner side of each plate cover in macrodilution assays. Among all tested substances, the strongest and broadest activity was shown by the oils of wintergreen (Gaultheria procumbens), oregano (Origanum vulgare), and lemongrass (Cymbopogon flexuosus. Carvacrol (64.0-75.8%) was the dominant component of oregano oils, while geranial (40.7%) and neral (26.7%) were the major constituents of lemongrass oil. Xanthomonas campestris pv. phaseoli was the most sensitive to plant essential oils, being susceptible to 19 oils, while 11 oils were bactericidal to the pathogen. Sixteen oils inhibited the growth of Clavibacter michiganensis subsp. michiganensis and seven oils showed bactericidal effects to the pathogen. The least sensitive species was Pseudomonas tolaasii as five oils inhibited bacterial growth and two oils were bactericidal. Wintergreen, oregano, and lemongrass oils should be formulated as potential biochemical bactericides against different horticultural pathogens.

A preliminary study of antibacterial activity of thirty essential oils against several important plant pathogenic bacteria

“…syringae was noticed. Todorović et al (2016) reported the strongest and broadest antibacterial activity of wintergreen, oregano and lemongrass oils against X. campestris pv. phaseoli, Clavibacter michiganensis subsp.…”

“…Therefore, search for novel alternative crop protectants is becoming more and more important. Recently, a wide range of essential oils (EOs) have been extensively studied for their antibacterial activity against many plant pathogenic bacteria (Deans & Ritchie, 1987;Vasinauskiene et al, 2006;Dadasoglu et al, 2011;Kokoskova et al, 2011;Hossein Nezhad et al, 2012;Badawy & Abdelgaleil, 2014;Gormez et al, 2013Gormez et al, , 2015Gakuubi et al, 2016;Todorović et al, 2016;Popović et al, 2017), usually using a direct-contact antimicrobial assay (Bajpai et al, 2011). Essential oils as products of plant secondary metabolism are the most interesting substances possessing antimicrobial activity (Deans & Ritchie, 1987).…”

Antifungal activity of plant essential oils against Verticillium dahliae Klebahn, the causal agent of verticillium wilt of pepper

“…The main components of the peppermint essential oil were menthone (37.02%), menthol (29.57%) and isomenthone (9.06%). Analysing 22 essential oils from Germany and Albania, Todorović et al (2016) found those of wintergreen lemongrass and oregano to demonstrate the strongest antimicrobial activity against three pathogenic bacteria (Xanthomonas campestris pv. phaseoli, Clavibacter michiganensis subsp.…”

“…Among the 22 essential oils analyzed, those of wintergreen (Gaultheria procumbens L.), lemongrass (Cymbopogon flexuosus Stapf.) and oregano have demonstrated the strongest antimicrobial activity against three pathogenic bacteria and parasites of common bean, tomato and cultivated mushroom (Todorović et al, 2016).…”

Antibacterial activity of some essential oils on bacterial spot disease of tomato plant caused by Xanthomonas axonopodis pv. vesicatoria

“…This growing interest in finding bio-pesticides in order to control the diseases is emphasized by the fact that the diseases caused by the plant pathogenic bacteria of Xanthomonas species are still a major problem even in the developed countries (McManus et al, 2002). Recently, a wide range of essential oils (EOs) have been extensively studied for their activity against many phytopathogenic bacteria (Gormez et al, 2015;Gakuubi et al, 2016;Todorović et al, 2016;Popović et al, 2017), usually using a direct-contact antimicrobial assay (Bajpai et al, 2011). Polyphenol oxidases (PPOs) are a group of Cu-containing enzymes that catalyse the oxidation of several phenols to o-quinones (Oliveira et al, 2011;van Gelder et al, 1997).…”