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Exploring the Relationship Among Divergence Time and Coding and Non-coding Elements in the Shaping of Fungal Mitochondrial Genomes

Summary

This research examined how fungal mitochondrial genomes (the DNA inside cellular powerhouses) change over evolutionary time. The study revealed that non-coding DNA segments play a major role in shaping these genomes, with faster-evolving species accumulating more of these elements. This has implications for understanding how organisms evolve and adapt. Impacts on everyday life: • Helps understand how fungi evolve and adapt to new environments • Provides insights for developing better antifungal treatments • Advances our knowledge of cellular energy production • Could lead to improvements in biotechnology applications using fungi • Contributes to understanding biological diversity and evolution

Background

The order Hypocreales (Ascomycota) is composed of ubiquitous and ecologically diverse fungi such as saprobes, biotrophs, and pathogens. Despite their phylogenetic relationship, these species exhibit high variability in biomolecules production, lifestyle, and fitness. The mitochondria play an important role in fungal biology, providing energy to the cells and regulating diverse processes, such as immune response. In spite of its importance, the mechanisms that shape fungal mitogenomes are still poorly understood.

Objective

To investigate the variability and evolution of mitogenomes and its relationship with the divergence time using the order Hypocreales as a study model. The study aimed to sequence and annotate for the first time Trichoderma harzianum mitochondrial genome (mtDNA) and compare it to 34 other mtDNAs species that were publicly available.

Results

Comparative analysis revealed substantial structural and size variation in non-coding mtDNA regions, despite conservation of copy number, length, and structure of protein-coding elements. A highly significant correlation was found between mitogenome length and the number/size of non-coding sequences. Group I and II introns and homing endonucleases genes were the main contributors to discrepancies in mitogenomes structure and length. Several intronic sequences displayed sequence similarity among species, with some conserved at gene positions across most mitogenomes.

Conclusion

The study demonstrated that introns and homing endonuclease genes are key elements in mitogenome shaping. Their presence in fast-evolving mtDNAs could be mostly explained by divergence time, although intron sharing profiles suggest other mechanisms like horizontal transfer are also involved in mitochondrial genome evolution. Species that evolve faster showed higher frequency of non-coding elements in their mitogenomes.
  • Published in:Frontiers in Microbiology,
  • Study Type:Comparative Genomic Analysis,
  • Source: 10.3389/fmicb.2020.00765
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