Plant diseases are a major threat to crop yield in agriculture, impacting the food security and the economy. The pathogenic fungus Moniliophthora perniciosa (Mp) is responsible for causing the witches' broom disease (WBD) of cacao (Theobroma cacao), whose seeds are the exclusive raw material for chocolate manufacture, leading to catastrophic cacao yield losses in South America. Mp is a hemibiotrophic fungus that colonizes the host apoplast during the biotrophic stage up to 90 days, causing the distinctive symptoms of WBD, including loss of apical dominance and hypertrophic growth of infected shoots. Currently, the methods for WBD containment have limited efficacy. Although some studies have investigated the molecular aspects of the Mp x cacao interaction, the knowledge regarding the molecular basis of Mp resistance and the gene-for-gene relationship between host immunity and fungal avirulence genes remain unknown. As a perennial tree, the study of the molecular aspects of pathogenesis in cacao is challenging. Mp is capable of infecting diverse hosts, being classified into the L, C, and S biotypes, which colonizes lianas, Theobroma, and Solanaceae species, respectively. Cross-infection of their hosts rarely occur, but the genetic relationship and the molecular aspects that determine host specificity in this pathogen remans unexplored. Here, we use the tomato (Solanum lycopersicum) Micro-Tom (MT) and, unprecedentedly, Nicothiana bentamina (Nb), infected by the S and C biotypes, respectively, as model systems to understand Mp pathogenesis. We propose to evaluate proteins retrieved by the apoplastic fluid of inoculated MT and Nb to investigate Mp effectors during the biotrophic phase of infection. Furthermore, we intend to use the Virus-induced gene silencing (VIGS) technique to silence genes required for PRR and NLR functions and evaluate the inoculation by the C and S biotypes of Mp. This approach may reveal if incompatibility of Mp infection is related to the perception of virulence factors by the host, and clarify what type of plant receptors responsible for playing this role. The knowledge regarding effector localization and functions and the molecular mechanisms related to host immunity and defense are essential approaches to dissect the pathoystem and stablish WBD control strategies.
News published in Agência FAPESP Newsletter about the scholarship: