Unveiling the Unique Mitogenome Structure of Phylloporus: Implications for Phylogeny and Evolution in Boletaceae

The genus Phylloporus (Boletaceae, Boletales) is a group of ectomycorrhizal fungi, distinguished from other members of Boletaceae by its unique lamellate hymenophore. Although some molecular data exist for this genus, its mitogenomic characteristics remain poorly understood. In our study, we sequenced, assembled, and annotated the complete mitogenomes of eight species representing seven major subclades of Boletaceae collected in Jiangxi Province, China, with a focus on four Phylloporus species. We found that Phylloporus mitogenomes are circular, ranging in size from 35,117 bp to 38,908 bp, and contain 14-15 core protein-coding genes (PCGs), 24-28 tRNA genes, and 2 rRNA genes. Our comparative analysis revealed that Phylloporus species share many features, such as gene content, gene length, tRNA repertoire, and gene order, while Boletaceae as a whole shows a lot of diversity. Codon usage patterns are quite similar across the family. The Ka/Ks ratios of most 15 core PCGs were less than 1, suggesting these genes have been preserved through purifying selection over time. By using Bayesian inference (BI) and maximum likelihood (ML) methods and combining 28 other mitotic genomes in the NCBI database, our phylogenetic analysis produced highly consistent and well-supported trees (BPP ≥ 0.98, BS ≥ 71). It is noted that this family is divided into seven subfamilies, which is consistent with previous taxonomic studies. Altogether, our findings shed light on the unique features of Phylloporus and its connections to other members of Boletaceae. These findings not only provide valuable insights into the taxonomy, phylogeny, genetic diversity, and resource conservation of Boletaceae but also serve as a valuable genomic resource for future research.