Characterization of a carrier of drugs with possible role in fungicide resistance in pathogen Moniliophthora perniciosa, the cause of witches' broom of cacao tree

Abstract

Until the middle of the decade of 1990, cocoa was a major product in the Brazilian economy and the country appeared as one of its biggest exporters. However, after the introduction of witches' broom disease in the southern state of Bahia, the national cocoa production had declined considerably. As a result, the country began importing the product to meet the demand of the domestic chocolate industry. The witches' broom is caused by the basidiomycete Moniliophthora perniciosa and affects stems and fruit of the cacao tree. Traditional methods of control based on the application of fungicides have been shown to be inefficient, possibly due to the existence of resistance mechanisms of the pathogen. The Witches' Broom Genome Project has allowed to elucidate some of these mechanisms. Recently, our group started the construction of the "Transcriptomic Atlas of Witch Broom", the result of sequencing of transcriptomes of various growth conditions and developmental stages of the pathogen M. perniciosa, as well as its interaction with the cocoa. Notably, the inspection of the fungus transcriptomes treated with fungicides led to the identification of mechanisms seem to contribute to drug resistance to the pathogen. In this regard, a gene encoding an integral membrane protein, called Mpflr1, were found highly expressed by the fungus after treatment with fungicides. The protein encoded by this gene have similarities to the carrier FLR1 of Saccharomyces cerevisiae, which acts as efflux pump of xenobiotics. This project aims to determine if the carrier MpFLR1 of M. pernicious is indeed a mechanism of drug resistance. For this purpose, the gene flr1 of S. cerevisiae will be deleted and the resulting strain will be complemented with the gene Mpflr1 of M. perniciosa. Functional assays will be performed to assess the role of the protein MpFLR1 in yeast resistance to various xenobiotics. The results of this study will be of great importance for better understanding of mechanisms of resistance to fungicides in pathogen M. pernicious and may contribute to the development of future strategies to control witches' broom disease.