Eight New Sedum Plastomes: Comprehensive Analyses and Phylogenetic Implications

Area of Science:

• Plant evolutionary biology
• Molecular systematics
• Genomics

Background:

• Sedum is a large, taxonomically complex genus within the Crassulaceae family, important in horticulture.
• Previous studies on Sedum and Crassulaceae phylogeny have yielded debatable results.
• Understanding the evolutionary branching patterns within Sedum and its family is crucial.

Purpose of the Study:

• To investigate the phylogenetic relationships within the Sedum genus and the broader Saxifragales order.
• To analyze plastome diversity, including nucleotide variations, microsatellite repeats, and RNA editing sites.
• To examine gene content at Inverted Repeat (IR) junctions for family-specific patterns.

Main Methods:

• Sequencing and comparative analysis of plastomes from eight Sedum species.
• Phylogenetic inference using 79 protein-coding genes (PCGs) from 148 Saxifragales species.
• Analysis of IR junction variations, microsatellite repeats, and putative RNA editing sites.

Main Results:

• A unique 110 bp IR extension into rps19 was identified, conserved across Crassulaceae, suggesting a family-specific trait.
• Phylogenetic analyses confirmed the polyphyly of Sedum.
• Specific relationships were resolved, e.g., S. emarginatum is closer to S. makinoi than S. alfredii.

Conclusions:

• The study provides valuable plastid sequence data for Sedum, Crassulaceae, and Saxifragales.
• Findings enhance the understanding of evolutionary dynamics within these plant groups.
• The identified IR extension highlights a unique evolutionary pattern within the Crassulaceae family.