Despite the importance as sources of medicines, timber, fruits, spices and perfumes, the classification of Lauraceae is poorly known and their broad-scale classification has depended traditionally on the morphology of inflorescences and flowers. 

Prof. LI Jie's team from the Xishuangbanna Tropical Botanical Garden (XTBG) previously used standard DNA plant barcodes to resolve Lauraceae relationships and classification by sampling multiple individuals per species. However, the resolution was poor. 

In a new study published in Botanical Journal of the Linnean Society, XTBG researchers and their collaborators investigated whether the plastome can improve species discrimination relative to standard DNA barcodes in Lauraceae. 

The researchers compared standard DNA barcoding to plastid genome sequencing for species discrimination in the family Lauraceae, using 191 plastid genomes for 131 species from 25 genera. 

"Our genomes represent the largest plastome data set for Lauraceae to date," said Dr. LIU Zhifang, first author of the study. 

They found that the plastid genome data resulted in a modest increase in discriminatory power in Lauraceae compared to standard DNA barcodes or regions selected for the family. The plastome data set also provided a useful phylogenetic framework for the family. However, there remain cytonuclear discordance and only represent a modest improvement in discrimination success with the standard plant DNA barcodes.  

The researchers thus emphasozed that caution is needed in the interpretation of plastomes and/or nrDNA phylogenetic analyses of the family.  

"Although plastome sequences are useful for improving phylogenetic resolution in the family and providing some species-level insights, they only partially improve species discrimination," said Prof. LI Jie, principal investigator of the study.