Assembly, Annotation, and Comparative Analysis of Mitochondrial Genomes in Trichoderma.

Abstract

Trichoderma is a widely studied ascomycete fungal genus, including more than 400 species. However, genetic information on Trichoderma is limited, with most species reporting only DNA barcodes. Mitochondria possess their own distinct DNA that plays a pivotal role in molecular function and evolution. Here, we report 42 novel mitochondrial genomes (mitogenomes) combined with 18 published mitogenomes of Trichoderma. These circular mitogenomes exhibit sizes of 26,276-94,608 bp, typically comprising 15 core protein-coding genes (PCGs), 2 rRNAs, and 16-30 tRNAs; however, the number of endonucleases and hypothetical proteins encoded in the introns of PCGs increases with genome size enlargement. According to the result of phylogenetic analysis of the whole mitogenome, these strains diverged into six distinct evolutionary branches, supported by the phylogeny based on 2830 single-copy nuclear genes. Comparative analysis revealed that dynamic Trichoderma mitogenomes exhibited variations in genome size, gene number, GC content, tRNA copy, and intron across different branches. We identified three mutation hotspots near the regions encoding nad3, cox2, and nad5 that caused major changes in the mitogenomes. Evolutionary analysis revealed that atp9, cob, nad4L, nad5, and rps3 have been influenced by positive selection during evolution. This study provides a valuable resource for exploring the important roles of the genetic and evolutionary dynamics of Trichoderma mitogenome in the adaptive evolution of biocontrol fungi.