Investigation of the metabolic alterations of the fungus Moniliophthora perniciosa, causal agent of the Witches' broom disease of cacao, related to the resistence to antifungal agents inhibiting the enzyme oxidase alternative

Abstract

Cacao (Theobroma cacao) is a plant originated in the Amazon basin that has great economic relevance for supplying the raw material for the manufacture of various products, such as chocolate, beverages and cosmetics. However, one of the major causes of losses in its production are fungal diseases, such as the Witch's Broom present in Brazil and whose etiological agent is the fungus basidiomycete Moniliophthora perniciosa. Studies related to this disease have led to the identification of the mitochondrial enzyme Oxidase Alternative (MpAOX), which has great importance for the survival and virulence of M. perniciosa, especially during the initial stages of its life cycle. Therefore, MpAOX is configured as a potential target for the targeted development of new fungicides. On the other hand, there are as yet no AOX inhibitors suitable for use as agricultural pesticides. Thus, our group performed a series of tests to evaluate the antifungal effect of AOX inhibitors on M. perniciosa and other phytopathogens relevant to Brazilian agriculture, such as Sclerotinia sclerotiorum and Venturia pyrina, which cause Mofo Branco and Sarna de Pera diseases, respectively. A marked difference in the ability of these inhibitors to restrict the mycelial development of the fungi tested was observed. Remarkably, M. perniciosa demonstrated great resistance to all of them, unlike S. screrotiorum and V. pyrina, which exhibited sensitivity to AOX inhibitors. On the other hand, these inhibitors were able to prevent germination of M. perniciosa spores in vitro, indicating that the resistance phenomenon observed in the M. myrnium mycelium may be related to physiological characteristics in these cells and are not found in the spores and nematodes. in the other fungi tested. For example, it is known that M. perniciosa has undergone an expansion in the number of genes encoding proteins of the Cytochrome P450 Oxygenases family (CYP450), notably involved in the metabolism of xenobiotics. Therefore, the present project aims to investigate the metabolic profile of M. perniciosa and the possible role of CYP450 as a mechanism of resistance to an AOX inhibitor of coletochlorin B class, through a comparative analysis of transcriptomics and metabolomics. The identification of genes and metabolic pathways involved in resistance to fungicide, as well as elucidation of possible chemical changes suffered by the inhibitor, will be achieved through the technique of RNA-seq. This will yield relevant information for the targeted development of new, more effective AOX inhibitors than are currently available and best suited for commercial use. (AU)