Comparative Genomics of Different Lifestyle Fungi in Helotiales (Leotiomycetes) Reveals Temperature and Ecosystem Adaptations.

Helotiales, a diverse fungal order within Leotiomycetes (Ascomycota), comprises over 6000 species occupying varied ecological niches, from plant pathogens to saprobes and symbionts. Despite their importance, their genetic adaptations to temperature and environmental conditions are understudied. This study investigates temperature adaptations in infection genes and substrate degradation genes through a comparative genomics analysis of 129 Helotiales species, using the newly sequenced genomes of and . Key gene families such as cytochrome P450 enzymes, virulence factors, effector proteins, and carbohydrate-active enzymes (CAZymes) were analyzed to understand their roles in temperature and lifestyle adaptations, uncovering possible alternative lifestyle mechanisms. Our findings reveal that Helotiales fungi possess genes associated with nutrient acquisition, pathogenicity, and symbiotic relationships strongly adapted to cold environments that might be impacted by global warming. On the other hand, some species demonstrate potential for adaptation to warmer climates, suggesting increased activity in response to global warming. This study reveals the adaptive mechanisms enabling Helotiales fungi to thrive in both cold and warm environments. These findings provide valuable insights into their ecological success and evolutionary resilience, which may facilitate their ability to transition between pathogenic, symbiotic, and saprobic phases in response to changing environmental conditions.