Lauraceae play an important role in tropical and subtropical forests, often as canopy dominants and also have economic significance as sources of medicine, timber, spices, nutritious fruits and perfumes. However, scant information is available regarding accurate classification and biodiversity assessment within this family.

Owing to lack of clear-cut morphological differences between genera and species, this family is an ideal case for testing the efficacy of DNA barcoding in the identification and discrimination of species and genera. 

Prof. LI Jie and his team from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences used existing molecular barcodes: three cpDNA regions (rbcL, matK, psbA–trnH) and the nuclear marker ITS (ITS1+5.8S+ITS2), as well as the subunit ITS2, to examine the taxonomic classification and phylogeny of Lauraceae.

In total, they obtained 1474 sequences from the 409 samples, representing 133 species of 12 genera after correction. 

The researchers tested the ability of DNA barcoding to distinguish species and as an alternative tool for correcting species misidentification. They also used the rbcL+matK+trnH–psbA+ITS loci to investigate the phylogenetic relationships of the species examined. 

The barcodes produced positive results for correcting species identification errors and reconstructing phylogenetic relationships of Lauraceae, even though identification rates were not high.

Among the gene regions and their combinations, ITS was the most efficient for identifying species (57.5%) and genera (70%). DNA barcoding also had a positive role for correcting species misidentification (10.8%). 

Furthermore, the researchers advocated the use of DNA barcodes, in combination with other techniques, because DNA barcoding plays an important role in the conservation of rare species and for forest crime prosecutions. It will contribute to develop adequate management strategies for the long term conservation of Lauraceae. 

However, there is also critical need for additional data from both more taxa and more sequence regions to help resolve issues in Lauraceae taxonomy and conservation, as there is clearly no simple one-size-fits-all barcoding solution for the family. 

The study entitled “DNA barcoding evaluation and implications for phylogenetic relationships in Lauraceae from China” has been published in PLoS ONE.  

 A kind of Lauraceae in the field. (Image by LIU Zhifang)