In vitro antifungal activity of Myrcia ovata essential oils and their major compounds against pathogens of citrus, sweet potato, and coconut

Abstract


 Myrcia ovata, an endemic species to the Brazilian Atlantic Forest, presents antifungal properties. The phytopathogens Colletotrichum acutatum, Plenodomus destruens, and Thielaviopsis paradoxa are responsible for the diseases citrus postbloom fruit drop, sweet potato foot rot, and coconut stem bleeding, respectively. The antifungal activity of the essential oils of five M. ovata chemotypes (MYRO-159, nerolic acid chemotype; MYRO-180, nerolic acid + linalool chemotype; MYRO-388, geraniol chemotype; MYRO-157, citral + (E)-nerolidol chemotype; and MYRO-174, isopulegol + linalool chemotype), four major compounds (nerolic acid, nerolic acid + linalool, geraniol, and citral + (E)-nerolidol), and three pure compounds (citral, (E)-nerolidol, and linalool) against the fungi C. acutatum, P. destruens, and T. paradoxa were evaluated. For this, in vitro tests were conducted in a completely randomized design with three replications, testing concentrations (v/v) ranging from 0.01 to 1.0 μL.mL-1. All treatments presented toxicity at different levels to the three fungi. For C. acutatum, the essential oil from the individual MYRO-180 (nerolic acid + linalool chemotype) and its major compound showed the lowest Minimal Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) of 0.03 and 0.1 µL.mL-1, respectively. For P. destruens, the essential oil from the individual MYRO-159 (nerolic acid chemotype) presented the lowest MIC of 0.05 μL.mL-1. The nerolic acid + linalool chemotype and its major compound presented an MFC of 0.07 μL.mL-1. For T. paradoxa, the major compound citral + (E)-nerolidol stood out with the lowest MIC and MFC of 0.03 and 0.2 µL.mL-1, respectively. Linalool presented the lowest toxicity to the three tested fungi.

Identification, Characterization, and Evaluation of Nematophagous Fungal Species of Arthrobotrys and Tolypocladium for the Management of Meloidogyne incognita

“…The activity of these compounds as a repellent, odor character, insecticides, and nematicides have already been reported earlier by Huang et al (2018) and Mravčáková et al (2021). Similarly, the compounds, dodecadienal, undecane, and nerolic acid observed throughout metabolite profiles in the present study have already been reported as nematicidal, antibacterial, and antifungal compounds (Caboni et al, 2012;White et al, 2019;Sarsaiya et al, 2020). Correspondingly, A. thaumasia At_RK secreted non-volatile compounds such as aganing, talathermophilin, and dactylarin found in other nematophagous fungi, A. entomopa, Talaromyces thermophilus, and Dactylaria lutea (Kettner et al, 1973;Degenkolb and Vilcinskas, 2016;Wang X. et al, 2017).…”

“…Identification of volatile organic compounds (VOCs) of A. thaumasia and T. cylindrosporum using GC-MS analysis. Ferula assa-foetida oil, having antibacterial activity against Streptococcus mutans, S. sanguis, S. salivarius, S. sobrinus, and Lactobacillus rhamnosus(Daneshkazemi et al, 2019) Salmali Niryasa having antimicrobial activity against Klebsiella pneumoniae, Staphylococcus aureus, E. coli, and Candida albicans(Divya and Prabhu, 2015) It was found in Myrcia ovata oils having antifungal activity against Colletotrichum acutatum, Plenodomus destruens, and Thielaviopsis paradoxa(White et al, 2019) Salmali niryasa having antimicrobial activity against Klebsiella pneumoniae, Staphylococcus aureus, E. coli, and Candida albicans(Divya and Prabhu, 2015) …”