Heterologous Systems in the Functional Characterization of Proteins from Phytopathogenic Fungi: A Systematic Review

Fungal-host coevolution, intensified by climate change, is attracting greater efforts to characterize new virulence proteins to enable the protection of agricultural crops. Under PRISMA guidelines, in this systematic review we analyzed 122 experimental studies from the Scopus, PubMed, ScienceDirect, and Web of Science databases, mapping heterologous expression systems for fungal phytopathogen proteins from crops such as wheat, maize, rice, and apple, among other agricultural commodities. The results reveal the predominance of Escherichia coli, Saccharomyces cerevisiae, Pichia pastoris, Nicotiana benthamiana, and filamentous fungi in structural and functional validation, both in vitro and in vivo. Although these heterologous hosts elucidate relevant pathogenicity mechanisms and immune suppression, gaps persist, such as the restricted use of filamentous fungi as models and the absence of standardized workflows for the integrated characterization of proteins across multiple hosts. By systematizing bibliometric trends and methodological approaches, this study reveals different strategies used to accelerate the analysis of fungal proteins, contributing to the advancement of molecular phytopathology and global food security.