Evaluation of the hormonal profile at the beginning of infection in model plants for the study of biotype-specific resistance to the pathogen Moniliophthora perniciosa

• Grant number: 24/01828-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2024
• End date: April 30, 2026
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Principal Investigator: Antonio Vargas de Oliveira Figueira
• Grantee: João Gabriel Dantas de Aguiar
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

"Witches' broom" is an important disease that affects cocoa trees (Theobroma cacao), limiting cocoa production. The etiological agent of the disease is the fungus Moniliophthora perniciosa, a basidiomycete with a hemibiotrophic lifestyle. M. perniciosa isolates are capable of colonizing a range of hosts, ranging from species of the genus Theobroma to solanaceae and wild lianas: the isolates that infect cocoa trees belong to biotype-C and those that colonize solanaceae are of the S-biotype. The symptoms of "witches' broom" in the biotrophic phase are loss of apical dominance, excessive sprouting and enlargement of the infected stem and branches, occurring both in cocoa trees and during the colonization of solanaceae, including the inoculation of tomato plants of a grow crop called "Micro-Tom". The symptoms typical of M. perniciosa infection were preliminarily suggested as resulting from hormonal imbalance in the host; However, to date, reports of hormonal imbalance occurs mainly from studies in the advanced part of the biotrophic phase and have alluded to compatible interactions. Recently, an analysis of RNA-seq comparing MT plants inoculated with the S- and -C biotypes of M. perniciosa in the first hours of colonization revealed an induction of genes associated withjasmonic acid (JA) and ethylene (ET) in plants inoculated with biotype-C (interaction incompatible), providing a role for these hormones in resistance to the C-biotype. In addition, we adopted a new model susceptible to the C-biotype of M. perniciosa, the grow crop N. benthamiana. In this work we propose hormone quantification analyzes throughout MT and N. benthamiana infection to characterize the colonization process by M. perniciosa comparing compatible and incompatible interactions to investigate which hormones affect the induction of susceptibility and which are related to resistance to this pathogen. These results will suggest which factors are associated with the success or failure of M. perniciosa infection, as they are unknown,but essential to understand the innovative strategies by the pathogen and defense responses by the host.