Comparative genomics and evolutionary analyses of Sphaeropleales.

Area of Science:

• * Algology and Genomics
• * Evolutionary Biology and Ecology

Background:

• * Sphaeropleales comprises over 1000 species known for environmental adaptability.
• * Genomic data for this diverse algal group is expanding.

Purpose of the Study:

• * To perform comprehensive genomic analyses of seven new Sphaeropleales strains.
• * To conduct comparative assessments with existing Sphaeropleales genomes.
• * To understand ecological adaptations and evolutionary relationships within Sphaeropleales.

Main Methods:

• * Sequencing of seven Sphaeropleales strains with high BUSCO completeness (>90%).
• * Comparative genomic analyses including orthologous and functional assessments.
• * Phylogenetic studies using 18S rDNA and low-copy orthologues.

Main Results:

• * Genome sizes vary (39.8–151.9 Mb) with ~56% GC content.
• * Unique gene families identified in each strain (2–3.5%).
• * Transporters, pyrroline-5-carboxylate reductase, and antioxidant genes are key for stress adaptation.
• * Sphaeropleales are B12 auxotrophic, relying on bacterial symbionts.
• * Terrestrial *Bracteacoccus* species show rapid evolution and gene family expansion.

Conclusions:

• * Genomic insights enrich understanding of Sphaeropleales, especially *Bracteacoccus*.
• * Key genes facilitate adaptation to diverse environmental stressors.
• * Findings support evolutionary relationships and potential biotechnological applications.