Fungal NR-PKS phylogeny: current classification and putatively new groups.

Fungal non-reducing polyketide synthases (NR-PKSs) play an essential role in the production of natural products, many of which have pharmaceutical applications. However, their phylogenetic classification remains only partially resolved. This study aims to investigate the current classification of fungal type I NR-PKSs across diverse fungal classes, and to explore the existence of putatively novel groups. A total dataset of 220 fungal genomes was retrieved from NCBI, and biosynthetic gene clusters (BGCs) were visualized through antiSMASH fungal version. A total of 1,883 amino acid sequences of type I NR-PKSs were extracted, aligned, and analyzed. A maximum-likelihood phylogenetic tree was built using IQ-TREE, and sister clades were identified through iTOL, based on enzymatic domain composition. These results support the presence of known NR-PKS subgroups while highlighting additional clades that may represent previously uncharacterized groups. This work contributes to refining NR-PKS classification and offers insights into the evolutionary diversity of fungal secondary metabolism.