An Integrated Identification Strategy for Closely Related Plants Mahonia Bealei, Mahonia Fortunei, and Berberis Soulieana Using Microscopic Characterization, HPLC-QTOF-MS/MS, and DNA Barcoding: A Controversial Case on the Taxonomy of Mahonia and Berberis.

INTRODUCTION:The taxonomic boundary between Mahonia and Berberis has long been controversial. Mahonia bealei (Fort.) Carr. (MB) and Mahonia fortunei (Lindl.) Fedde (MF) are representative species of Mahonia, while Berberis soulieana Schneid. (BS) represents Berberis. These three plants are often confused in practical medicinal use. OBJECTIVE:This study aims to elucidate the diagnostic characteristics and taxonomic relationships among MB, MF, and BS. It seeks to provide a potential basis for generic realignment. METHODOLOGY:Their structural differences were compared based on macro-morphological features of leaves and microscopic characteristics of roots. Qualitative and quantitative analyses of the chemical components in the three samples were carried out using HPLC-QTOF-MS/MS, followed by a comparison of their chemical fingerprints and the content of major components. Based on multiple DNA barcoding, interspecific genetic distances were calculated and RNA secondary structures were predicted. RESULTS:The differences in the root transverse sections provided a basis for distinguishing the three samples. A total of 67 compounds were identified using HPLC-QTOF-MS/MS, with 24 of these being common to all three samples. While their chemical fingerprints were highly similar, berberine content served as a key differentiating marker. Among DNA barcodes, PsbA3 exhibited the highest sequence variation and largest inter-species genetic distance. These properties made it the optimal barcode for discrimination. Notably, its secondary structure was relatively conserved, exhibiting a unique phenomenon of highly variable sequences with conserved structures. CONCLUSION:Although several diagnostic features were identified, the marked chemical similarities, conserved DNA barcodes, and shared microscopic characteristics provided novel insights into the taxonomic relationship between the genera Mahonia and Berberis.