# Boechera or not? Genomic insights and taxonomic reassessment of the misclassified Asian species B. calcarea (Brassicaceae)

## TL;DR

This study corrects the misclassification of a rare Brassicaceae species from Asia, revealing it belongs to a different tribe and emphasizing the value of integrative methods in taxonomy.

## Contribution

The paper resolves a taxonomic ambiguity by reclassifying B. calcarea as Parryodes calcarea and placing it within the Arabideae tribe using genomic and cytogenetic data.

## Key findings

- B. calcarea was reclassified as Parryodes calcarea and found to belong to the tribe Arabideae.
- The species exhibits Arabideae-specific chromosomal features, including centromere repositioning.
- An integrative approach combining cytogenetics, phylogenetics, and repeatome analysis proved critical for taxonomic resolution.

## Abstract

The genus Boechera (Brassicaceae) serves as a model system for studying apomictic reproduction and ecological adaptations, with most species occurring in North America. The rare occurrence of Boechera species outside their typical range provides unique opportunities to investigate genome evolution in extralimital environments. One such species, B. calcarea, has been described from the Chandalaz Mountains in northeastern Asia (Russia). This study aimed to investigate the genome structure and evolutionary history of B. calcarea. However, our analyses reveal that the species does not belong to Boechera. Instead, an integrative approach combining cytogenetic, phylogenetic and repeatome analysis identified the species as a member of one of more ancestral clades in the tribe Arabideae. The diploid Parryodes calcarea (2n = 16) exhibits Arabideae-specific chromosomal signatures, including multiple centromere repositionings. These findings clarify the misclassification of P. calcarea as Boechera, leaving Boechera falcata and Borodinia macrophylla as the only representatives of the Boechereae in the Old World. This study highlights the importance of an integrative approach in resolving taxonomic ambiguities and provides new insights into the diversification of the largest cruciferous tribe, the Arabideae.

•Cytogenetic, phylogenetic and repeatome analyses identified the new species formerly described as Boechera calcarea (Brassicaceae).•The new species, Parryodes calcarea, is a member of the tribe Arabideae•Importance of integrative approach in resolving taxonomic ambiguities.•New insights into the diversification of the largest cruciferous tribe.

Cytogenetic, phylogenetic and repeatome analyses identified the new species formerly described as Boechera calcarea (Brassicaceae).

The new species, Parryodes calcarea, is a member of the tribe Arabideae

Importance of integrative approach in resolving taxonomic ambiguities.

New insights into the diversification of the largest cruciferous tribe.