Enzymatic Activity in Essential Oil-Treated and Pathogen-Inoculated Corn Plants

Abstract

Bipolaris maydis and Exserohilum turcicum are important fungal pathogens that cause leaf blight in corn whose control have been difficult. Essential oils are a promising and environmentally friendly alternative for disease management, but the mechanisms of action remain poorly studied. Here, we aimed to assess the effect of B. maydis and E. turcicum as well as the essential oil of Morinda citrifolia in the activity of plant defense enzymes in corn plants. Experiments were carried out in a completely randomized design with three replications and six treatments as they follow: (T1): corn plants inoculated with B. maydis; (T2): corn plants inoculated with E. turcicum; (T3): corn plants treated with essential oil of M. citrifolia (0.25%) and inoculated with B. maydis; (T4): corn plants treated with essential oil of M. citrifolia (0.25%) and inoculated with E. turcicum; (T5): corn plants treated with essential oil of M. citrifolia (0.25%); and (T6): corn plants non-inoculated and treated with distilled water. Protein content (PC) and activities of the enzymes ascorbate peroxidase, catalase, chitinase (CHI), peroxidase (POX) and superoxide dismutase (SOD) were assessed. PC was significantly decreased, whereas CHI and SOD activity was higher in T1-T5 compared to T6. T4 and T5 significantly increased POX activity relative to T6. Therefore, our findings suggest that the essential oil of M. citrifolia may play an active role in disease control by activating defense enzymes in corn plants.

Reduction of Postharvest Quality Loss and Microbiological Decay of Tomato “Chonto” (Solanum lycopersicum L.) Using Chitosan-E Essential Oil-Based Edible Coatings under Low-Temperature Storage

“…The preservative effect of CS + RGEO coating might be due to a free-radical scavenging ability of the essential oil [ 35 ]. Additionally, some authors reported an increased stimulated activity of defense enzymes like superoxide dismutase (SOD), catalase (CAT), and peroxide dismutase (POD) in plants by the application of essentials oils [ 75 ]. This could account for the lower decay index of the fruits, which is regulated by the concentration of reactive oxygen species (ROS) [ 76 ].…”

Essential Oil of Baccharis dracunculifolia (Asteraceae) Decreases Alternaria Rot in Pitahaya

“…Octanoic acid is the major component of noni (Morinda citrifolia) essential oil, which was demonstrated to inhibit different plant pathogenic fungi, including Aspergillus niger, Aspergillus fumigatus, Bipolaris maydis, Colletotrichum gloeosporiodies, Curvularia spp., Exserohilum turcicum, Helminthosporium spp., Olivea neotectonae, Rhizopus oryzae and Sclerotium spp. (Sahoo et al, 2012;Silva et al, 2017;Osorio et al, 2018;Veloso et al, 2018Veloso et al, , 2020Dias et al, 2020). The chemical analysis of the essential oil of the plants that was used in the present study (EOB) showed high proportion of sesquiterpenes in the volatiles samples, such as δ-elemene, germacrene D, bicyclogermacrene, bicyclogermacrene, germacrene D and β-caryophyllene (Ascari et al, 2019;Brandenburg et al, 2020), whereas spathulenol and trans-nerolidol, both oxygenated sesquiterpenes, were the major compounds found in other study (Cazella et al, 2019).…”