Extracts of the Native Brazilian Tree Garcinia gardneriana Inhibit Urediniospore Germination of Coffee Leaf Rust Fungus

Ueveton Da Silva,Bianca De Sousa,Eduardo Varejão,João Paulo Leite,Ana Paula Agrizzi,Robert Barreto,Gabriela Furlani,Marcelo Dos Santos,Bruno Ferreira

doi:10.21577/0103-5053.20210139

Abstract

The fungal Hemileia vastatrix is the causal agent of coffee leaf rust, one of the worst and devastating disease in coffee cultures worldwide. As a result of our research on natural products for the development of novel agrochemicals, we found that the hexane extract from leaves of the Brazilian medicinal plant Garcinia gardneriana, at 500 μg mL–1, inhibited in 98% the germination of H. vastatrix urediniospores. This extract showed no phytotoxicity when tested for seed germination and seedling growth inhibitory activity using sensible plant species. Also, the hexane extract from leaves was tested for anti-acetylcholinesterase activity, which constitutes a mechanism of action of major commercial insecticides used in agriculture, and showed low activity even at concentrations about two times higher than the half maximal inhibitory concentration (IC50) found in the antifungal assays. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the hexane extract is constituted mainly by the pentacyclic triterpene lupeol, together with a series of sesquiterpenes as minor components. This is the first report on the investigation of antifungal, phytotoxic and acetylcholinesterase activities of extracts from leaves of G. gardneriana. These findings indicate that G. gardneriana may constitute a promising source of natural products for controlling the coffee leaf rust fungus.

Highlights

Garcinia gardneriana (Planch. & Triana) Zappi, popularly known as bacupari, is an herb native to the Amazon region and disseminated throughout the Brazilian territory
At 500 μg mL–1, the hexane extract produced high inhibition, which did not differ from that produced by the positive control copper oxychloride (p < 0.001)
Even though the IC50 value found for hexane extract is much higher than that for the commercial fungicide copper oxychloride, the hexane extract was capable of inhibiting over 98% of H. vastatrix conidia germination, at a concentration as low as 500 μg mL–1

Summary

Introduction

Garcinia gardneriana (Planch. & Triana) Zappi, popularly known as bacupari, is an herb native to the Amazon region and disseminated throughout the Brazilian territory. H. vastatrix is the causal agent of coffee rust, one of the worst fungal diseases of coffee plants and responsible for severe agricultural losses in coffee crops.[15,16] In Central America, H. vastatrix epidemics have been enhanced mainly due to climate changes that have made weather conditions more favorable to a faster spread of the fungus In these countries, coffee is often the sole source of income for many small farmers, so the decrease in coffee production caused by H. vastatrix has resulted in economic losses and a huge social impact.[17] In this context, several research groups have been focused on natural products, such as botanical extracts and essential oils, as sources of effective and with increased selective toxicity agents for the H. vastatrix control.[18,19,20,21]. Aerial parts were separated, dried at 40 °C, triturated, and subjected to solvent extraction

Extraction procedures

Results and Discussion

Literature

Conclusions