Functional analysis of the UACA gene in 'Micro-Tom' tomato and its role in the response to infection by pathogenic fungi

• Grant number: 25/03881-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: July 01, 2025
• End date: December 31, 2026
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Principal Investigator: Antonio Vargas de Oliveira Figueira
• Grantee: Raquel Giselli Assis do Rosário
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Witches' broom, caused by the fungus Moniliophthora perniciosa, severely affects cacao production, causing tissue deformation and necrosis. In Brazil, the introduction of the pathogen in southern Bahia in 1989 caused a 50 to 90% reduction in production, impacting the economy and generating a serious social crisis. Moniliophthora perniciosa is hemibiotrophic and it can be categorized into several biotypes that infect species of Theobroma, Solanaceae or lianas. The tomato plant Solanum lycopersicum cv Micro-Tom (MT) has been used as a genetic model because of the availability of mutants and of genetic manipulation protocol. The development of resistant cultivars depends on the identification of resistance genes. The UVEAL AUTOANTIGEN WITH COILED-COIL DOMAINS AND ANKYRIN REPEATS (UACA) gene was identified by mapping, present in a QTL at chromosome 9 of cacao, and it was putatively associated with the response to M. perniciosa infection. The function of UACA has not yet been described in plants, but in humans and mammals it regulates cell death. In cacao, UACA expression differs between resistant and susceptible cultivars, being underexpreed in resistant cultivars and overexpressed in susceptible in response to infection. The functional role of UACA in plants, particularly in pathogens response, remains to be elucidated and it could be associated with resistance against M. perniciosa. Previously, single-copy homologs from cacao (TcUACA) and tomato (SlUACA) were cloned. Overexpression of SlUACA and heterologous overexpression of TcUACA in MT could be associated with increased susceptibility to M. perniciosa, facilitating infection by the C-biotype of M. perniciosa. Conversely, CRISPR-Cas9-mediated knockout of SlUACA might enhance resistance to the S-biotype of M. perniciosa and other pathogenic fungi. Therefore, we aim to characterize the role of UACA in infection caused by M. perniciosa and other pathogenic fungi with distinct lifestyles, by inoculating plants that either overexpress SlUACA or have it knocked out. We seek to elucidate UACA function and contribute to the search for resistance to M. perniciosa in cacao. (AU)