Plastome Evolution in Dolomiaea (Asteraceae, Cardueae) Using Phylogenomic and Comparative Analyses

Area of Science:

• Plant genomics
• Molecular evolution
• Phylogenetics

Background:

• Dolomiaea, a medicinally important genus from the Qinghai-Tibet Plateau, lacks genomic resources, hindering evolutionary studies.
• Understanding the genomic landscape of Dolomiaea is crucial for its taxonomy, evolution, and conservation.

Purpose of the Study:

• To sequence and annotate plastomes of four Dolomiaea species.
• To identify molecular markers for species delimitation and population genetics.
• To investigate phylogenetic relationships and signatures of positive selection within Dolomiaea.

Main Methods:

• Whole-genome sequencing and comparative analysis of four Dolomiaea plastomes.
• Identification of highly divergent regions and simple sequence repeats (SSRs).
• Phylogenetic analyses using plastome data and selection pressure analysis.

Main Results:

• Conserved plastome structure and gene content across studied Dolomiaea species.
• Identification of eight highly divergent regions and 51-61 SSRs as potential molecular markers.
• Phylogenetic analyses placed Dolomiaea within Saussureinae, with discordance from morphological classifications.
• Discovery of positive selection signatures in four genes (atpA, ndhF, rbcL, ycf4), suggesting adaptation to alpine conditions.
• RpoC2 and ycf1 genes show high phylogenetic informativeness for Asteraceae.

Conclusions:

• The study provides the first genomic resources for Dolomiaea, establishing conserved plastome evolution.
• Identified molecular markers will aid future taxonomic and population genetic research.
• Phylogenetic findings challenge existing morphological classifications and highlight the utility of specific plastid genes.
• Positive selection in key genes suggests adaptive evolution to the unique alpine environment of the Qinghai-Tibet Plateau.