Characterization of an immune receptor responsible for the recognition of Xanthomonas citri subsp. citri in Nicotiana benthamiana

• Grant number: 20/12767-8
• Support type: Scholarships in Brazil - Doctorate
• Effective date (Start): May 01, 2021
• Effective date (End): August 31, 2024
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal researcher: Paulo José Pereira Lima Teixeira
• Grantee: Fernando Manuel Matias Hurtado
• Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

In nature, plants are continually exposed to a wide variety of pathogenic microorganisms. Yet, few are able to successfully colonize plant tissues and, consequently, cause disease. Even those microorganisms that are devastating to one plant species are often avirulent in others. Thus, most plants are naturally resistant to most pathogens. This phenomenon, known as non-host resistance, defines a durable resistance of all individuals of a plant species against all variants of a specific pathogen. Although multiple factors (e.g., chemical and physical barriers) can determine the compatibility between a pathogen and a plant, the plant immune system is believed to play a central role in many interactions. Using Xanthomonas citri subsp. citri 306 (Xcc306; a citrus pathogen) as a model, we are investigating whether the recognition of virulence effectors from the pathogen by intracellular receptors of the NLR (Nucleotide-Binding Leucine-Rich Repeat containing protein) family can determine resistance in non-host plants . An initial screening carried out by our group indicated that Xcc306 induces a strong immune response accompanied by cell death (HR; hypersensitivity response) in multiple plant species, including the model Nicotiana benthamiana. Subsequent experiments based on mutants revealed that, in fact, the immune response of N. benthamiana involves the recognition of Xcc306 effectors by plant NLR receptors. Subsequent screening revealed that one of the Xcc306 effectors is recognized by an NLR receptor that is still unknown in N. benthamiana. This work aims to identify this new receptor and determine its role in the resistance of N. benthamiana against Xcc306. We expect that the results of this project will contribute to the understanding of the basic mechanisms that govern non-host resistance, and may also lead to the identification of effective immune receptors against X. citri. (AU)