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

Mércia Freita Alves,Taís Santos Sampaio,Camila Santos Almeida-Pereira,Larissa Alves Secundo White,Daniela Aparecida De Castro Nizio,Paulo Roberto Gagliardi,Arie Fitzgerald Blank,Maria De Fátima Arrigoni-Blank

doi:10.14393/bj-v35n6a2019-42425

Mércia Freita Alves, Taís Santos Sampaio + Show 6 more

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https://doi.org/10.14393/bj-v35n6a2019-42425

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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.

Highlights

Phytopathogenic fungi, such as those of the phylum Ascomycota, are responsible for economic losses in planted forests and crops
Plenodomus destruens Hater, and Thielaviopsis paradoxa (De Seynes) Höhn. can attack plants anytime during the production cycle, especially at the pre-harvest stage. They are respectively responsible for the diseases citrus postbloom fruit drop, sweet potato foot rot, and coconut stem bleeding
The chemotype and major compound citral + (E)-nerolidol showed the same value of Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) (0.2 μL.mL-1) (Table 3 and Table 4)

Summary

Introduction

Phytopathogenic fungi, such as those of the phylum Ascomycota, are responsible for economic losses in planted forests and crops. Can attack plants anytime during the production cycle, especially at the pre-harvest stage They are respectively responsible for the diseases citrus postbloom fruit drop, sweet potato foot rot, and coconut stem bleeding. In periods of mild temperature and high humidity, which favor the permanence of wet leaves, the losses caused by citrus postbloom fruit drop can reach 80% of the production (GOES et al, 2008; GAMA, 2017). This same percentage of loss is detected in crops infected with sweet potato foot rot, especially when using repeated crops in the same area, with two or three harvests per year. It is considered as the main fungal disease in sweet potatoes (PEREIRA et al, 2011; FERNANDES, 2013)

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