The genus Caragana in the legume family is ecologically and pharmacologically important. Caragana plays a key role in the cold desert ecosystem throughout the Asian continent. However, accurate identification of taxa in the genus has been challenging. 

In a study published in Journal of Systematics and Evolution, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) tried to establish a DNA barcoding standard to enable reliable identification of Caragana species that will help in quality control procedures especially for highly fragmented herbal materials.  

The researchers conducted the most comprehensive taxon sampling of this genus. Using three analytical approaches (i.e. Pairwise Genetic Distance, Sequence Similarity and Phylogenetic Tree method), they explored the performance of four DNA barcoding regions nrITS, trnH-psbA, matK, and rbcL.   

They found that the nuclear ITS region was the most accurate and efficient barcode for distinguishing Caragana accessions/species. When employed individually or in combinations with trnH-psbA, it had the highest discriminatory rate and can differentiate between Caragana species.  

Unexpectedly, the previously recommended universal plant barcode rbcL + matK marker were ineffective as identifiers for Caragana species. Therefore, the researchers recommended the ITS alone or the concatenation of two regions (trnH-psbA + ITS) as plant barcodes in Caragana. 

"To our knowledge, the present study is the first attempt to utilize DNA barcoding for Caragana and its relatives,” said LIU Hongmei of XTBG. 

Contact 

LIU Hongmei Ph.D  

Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China                 

E-mail: liuhongmei@xtbg.org.cn   

First published: 26 July 2023