Expression mediated by virus (VOX) to understand Moniliophthora perniciosa effectors associated with host specificity during infection of Nicotiana benthamiana

• Grant number: 25/13260-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2025
• End date: October 31, 2026
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Principal Investigator: Antonio Vargas de Oliveira Figueira
• Grantee: Livia Akemi Tahara Amaral
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Cacao (Theobroma cacao) is a perennial tree species of great economic importance, serving as the seed source for an essential raw material in the chocolate and confectionery industries. The disease known as cacao witches' broom, caused by the fungus Moniliophthora perniciosa, represents one of the most significant threats to the crop, capable of inflicting losses of up to 90%. It is a pathogen with a complex hemibiotrophic life cycle. This fungus can be categorized into many biotypes with infection-specificities for distinct plant families, including cacao (biotype C) and species of the Solanaceae (biotype S), such as tomato (Solanum lycopersicum) cv. "Micro-Tom" (MT) and Nicotiana benthamiana, both species considered model systems for investigating plant-pathogen interactions. Host specificity in this interaction seems to be associated with the action of specific effectors, which include proteins secreted by the pathogen that modulate the host plant's immune response. Preliminary studies from our group indicate that virulent M. perniciosa isolates express specific genes encoding proteins, such as ceratoplatanins and PR-1, during the initial stage of infection in N. benthamiana. In contrast, avirulent isolates do not express these effectors. Molecular technologies, such as Virus-mediated Overexpression (VOX) using vectors based on Potato Virus X (PVX), offer efficient strategies to investigate the function of these effectors in the host plant. This project aims to utilize the VOX approach in N. benthamiana to overexpress specific effectors from virulent isolates of M. perniciosa in a transient form, testing their ability to confer susceptibility to the host in comparison to avirulent isolates. Therefore, we plan to advance our understanding of the molecular mechanisms that determine host specificity by biotype and the immune evasion process of the pathogen.