Perina FJ, Amaral DC, Fernandes RS, Labory CR, Teixeira GA, Alves E
Pest Management Science, 2014
In initial assays Thymus vulgaris essential oil (TEO) has demonstrated activity against several plant-pathogenic fungi and has reduced the fungal diseases to levels comparable to commercial fungicides. Thus, the goal of this work was to identify the mode of action in fungi of the TEO and its major compound thymol (henceforth called TOH) at cellular level using an ultrastructure approach.
TEO from leaves and TOH had minimal inhibitory concentrations (MICs) of 500 and 250 µg mL-1 respectively, against A. alternata; under the same conditions, MICs for commercial fungicides and TEO were 1250 and 500 µg mL-1 , respectively. Ultrastructure analysis showed that TOH phenolic substance prevented fungal growth, decreased fungal viability and prevented the penetration in fruits by a cell wall/plasma membrane interference mode of action with organelles targeted for destruction in the cytoplasm. Such mode of action differs from protective and preventive-curative commercial fungicides used as pattern control.
These findings suggest that TOH was responsible for the anti-fungal activity of TEO. Therefore, both the essential oil and its major substance have potential for use in the development of new phenolic structures and analogues to control Alternaria brown spot disease caused by A. alternata.
Perina FJ, Amaral DC, Fernandes RS, et al. Thymus vulgaris essential oil and thymol against Alternaria alternata (Fr.) Keissler: Effects on growth, viability, early infection, and cellular mode of action. Pest Manag Sci. 2014. doi: 10.1002/ps.3933.