O papel do hormônio auxina na virulência do patógeno de cacau >i /i<

Le résumé fourni par la source

The cacao tree (Theobroma cacao) is a crop of great socioeconomic importance in many tropical countries.One of the main limiting factors for cocoa production in Latin America is witches' broom disease (WBD), caused by the basidiomycete Moniliophthora perniciosa.Tissues affected by WBD show intense morphological changes and abnormal development, which indicate the occurrence of hormonal imbalances during the infection.However, the contribution of specific plant hormones to such changes remains poorly explored.Through transcriptomic analyses of the disease progression, we found that the increased expression of auxin-responsive genes constitutes one of the most notable molecular alterations in infected plants.Nevertheless, cacao genes involved in the production of auxins were not induced, suggesting that this response may be directly triggered by the pathogen.In fact, the investigation of the M. perniciosa genome revealed putative pathways for indole-3-acetic acid (IAA) production from Ltryptophan (Trp), indicating the potential of this fungus to produce auxins.In agreement with this prediction, supplementation of M. perniciosa cultures with Trp induced the accumulation of indole compounds, including IAA and indole-3-acetamide (IAM).In addition, the cell-free supernatant of pathogen cultures was able to activate the auxin response in both leaves and roots of Arabidopsis thaliana DR5::GFP, confirming the presence of biologically active IAA in these cultures.With the goal of obtaining mutants incapable of producing IAA, we worked on the establishment of a method to transform M. perniciosa, which was previously unavailable for this species.The resulting procedure is highly efficient and opens new avenues for unprecedented genetic manipulation of this pathogen through CRISPR/Cas9.Thus, our results establish solid foundations for the investigation of the role of IAA in the M. perniciosa virulence and in the development of WBD symptoms.

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