Structural and Transcriptional Diversity in the Repertoire of Sclerotinia sclerotiorum Effector Candidates

The necrotrophic fungal pathogen Sclerotinia sclerotiorum is distinguished by its exceptionally broad host range, infecting numerous plant species across diverse genera. While historically characterized by a seemingly unspecialized infection strategy, increasing evidence indicates that S. sclerotiorum employs a diverse suite of virulence mechanisms, including effectors for host and environment manipulation. Leveraging recent advances in structural genomics and the growing availability of genomic and transcriptomic resources, we systematically re-examined the effector repertoire of the reference strain 1980 using updated computational approaches. We identified 215 effector-like proteins, which were classified into structural families based on predicted tertiary structures. Transcriptome meta-analysis across hundreds of publicly available samples revealed diverse expression patterns among effectors, highlighting both conserved and condition-specific expression dynamics. Several effector families were found to be expanded in S. sclerotiorum, including groups with predicted antimicrobial functions and unique domain architectures. Within families, structural and surface property variation suggests potential functional diversification. Furthermore, co-expression network analysis uncovered putative gene clusters that may operate synergistically with selected effectors. This work refines our understanding of effector diversity and organization in S. sclerotiorum and provides a framework for prioritizing candidates for functional studies, ultimately contributing to the broader understanding of effector evolution in generalist fungal pathogens.