Phyllosticta on Citrus Exploring pathogenicity, genomics, and taxonomy

Citrus Black Spot (CBS), caused by the fungus Phyllosticta citricarpa, is a devastating disease that leads to significant economic losses in citrus production worldwide. In this thesis, I investigate key aspects of CBS and its closely related species to better understand fungal pathogenicity on citrus. First, I examine the fungi’s ability to grow on different substrates and explore whether these nutritional traits correlate with their capacity to cause disease. Next, I analyze genomic differences between pathogenic and non-pathogenic species to identify potential genetic determinants of virulence. To enable future functional genomics studies, I also develop and present a proof-of-principle CRISPR/Cas9-based genome editing system for one of these species. Finally, I resolve the ongoing taxonomic debate surrounding P. citricarpa and its sister species P. paracitricarpa. This work advances our understanding of pathogenicity in Phyllosticta species and provides new tools and insights that can support the development of improved disease management strategies for citrus crops.