Genomic factors limiting the diversity of Saccharomycotina plant pathogens

Area of Science:

• Mycology
• Plant Pathology
• Genomics

Background:

• The Saccharomycotina subphylum, despite extensive evolution, harbors few known plant pathogens.
• Plant pathogens within this group, primarily *Eremothecium* and *Geotrichum*, are rare compared to plant-associated strains.

Purpose of the Study:

• To identify unique genomic features of Saccharomycotina plant pathogens.
• To understand the evolutionary and metabolic basis of phytopathogenicity in this fungal group.

Main Methods:

• Comparative genomics of 12 plant-pathogenic and 360 plant-associated Saccharomycotina strains.
• Analysis of oxylipin synthesis genes and metabolic enzymes involved in plant defense.

Main Results:

• No differences were found in oxylipin synthesis genes between pathogenic and non-pathogenic strains.
• Plant pathogens lack essential metabolic enzymes like L-rhamnose metabolism, formamidase, and nitrilase.
• These enzyme deficiencies restrict Saccharomycotina pathogens to infecting only ripening fruits.

Conclusions:

• Saccharomycotina plant pathogens possess a limited enzymatic repertoire for overcoming plant defenses.
• Their inability to degrade phytohormones and secondary metabolites restricts their host range to vulnerable, ripening fruits.