An updated phylogeny of Boraginales based on the Angiosperms353 probe set: a roadmap for understanding morphological...

Area of Science:

• Plant Systematics and Phylogenetics
• Evolutionary Biology
• Angiosperm Taxonomy

Background:

• The order Boraginales, comprising approximately 2,700 species across 11 families, has a history of fluctuating classification at family and generic levels.
• Previous classifications relied heavily on gynoecium and fruit morphology, lacking a systematic evaluation integrating anatomical and ontogenetic data.

Purpose of the Study:

• To reconstruct robust phylogenetic relationships within the Boraginales order.
• To propose a revised family-level classification for Boraginales based on molecular phylogenetic data.
• To investigate the evolutionary significance of gynoecial and fruit morphology in diversification.

Main Methods:

• Phylogenetic analysis of 162 newly sequenced samples and 88 existing samples using the Angiosperms353 probe set.
• Comprehensive sampling covering over 80% of genera and all recognized families.
• Morphological assessment of gynoecial and fruit characters to inform taxonomic classification.

Main Results:

• Phylogenetic analyses yielded high resolution and strong support, largely consistent with prior studies but with novel insights.
• Hydrophyllaceae was resolved as nested within Namaceae, and the parasitic Lennoaceae was confirmed nested within Ehretiaceae.
• A total of nine families are proposed for Boraginales, with fully resolved tribal relationships within Boraginaceae subfamily Cynoglossoideae, and shifts in placentation and ovule number identified as key drivers of ovary evolution.

Conclusions:

• The Angiosperms353 probe set is effective for elucidating Boraginales evolutionary history, aiding in resolving remaining taxonomic uncertainties.
• Complex modifications in bicarpellate ovaries led to significant fruit diversification, playing a critical role in the macroevolution of Boraginales.
• Integration of this resolved phylogeny with future morphological studies will deepen the understanding of Boraginales evolutionary trajectories.