Leveraging target enrichment and genome skimming (Hyb-Seq) of herbarium collections to unlock timber DNA barcoding

DNA barcoding for timber species identification requires comprehensive reference datasets, informative DNA barcodes, and cost-effective protocols. We developed a workflow leveraging Hyb-Seq (target capture sequencing and genome skimming) to address these challenges, and we tested it on four genera from the mahogany family (Meliaceae).

We sequenced up to 350 nuclear and 177 plastid loci from 132 herbarium specimens representing leaf samples of 22 species. We determined the DNA barcoding potential of each locus by looking at species recovery and monophyly in gene trees. We then selected 13 short regions (candidate barcodes) within high-potential loci and tested their PCR amplification and Sanger sequencing on wood DNA.

Three candidate barcodes emerged as the most reliably sequenced from wood DNA and as providing the most accurate species-level identifications, with species monophyly rates above 80%. Failure to obtain sequences from some wood DNA extracts was more often associated with potential DNA impurity (as inferred from DNA color) than with DNA degradation.

Our reference data and candidate barcodes provide a foundation to support the DNA barcoding of mahogany and its relatives. Our workflow illustrates how the wealth of Hyb-Seq data currently generated from global herbaria may be leveraged to monitor plant diversity.