Barcode UK: A complete DNA barcoding resource for the flowering plants and conifers of the United Kingdom.

Laura Jones,Michelle L Hart,Helena Davies,Peter M Hollingsworth,Heather Mchaffie,Tim C G Rich,Alex D Twyford,Laura L Forrest,Max R Brown,Col R Ford,Natasha Vere

doi:10.1111/1755-0998.13388

Abstract

DNA barcoding and metabarcoding provide new avenues for investigating biological systems. These techniques require well-curated reference libraries with extensive coverage. Generating an exhaustive national DNA barcode reference library can open up new avenues of research in ecology, evolution and conservation, yet few studies to date have created such a resource. In plant DNA barcoding, herbarium collections provide taxonomically robust material but also pose challenges in lab processing. Here, we present a national DNA barcoding resource covering all of the native flowering plants and conifers of the United Kingdom. This represents 1,482 plant species, with the majority of specimens (81%) sourced from herbaria. Using Sanger sequencing of the plant DNA barcode markers, rbcL, matK, and ITS2, at least one DNA barcode was retrieved from 98% of the UK flora. We sampled from multiple individuals, resulting in a species coverage for rbcL of 96% (4,477 sequences), 90% for matK (3,259 sequences) and 75% for ITS2 (2,585 sequences). Sequence recovery was lower for herbarium material compared to fresh collections, with the age of the specimen having a significant effect on the success of sequence recovery. Species level discrimination was highest with ITS2, however, the ability to successfully retrieve a sequence was lowest for this region. Analyses of the genetic distinctiveness of species across a complete flora showed DNA barcoding to be informative for all but the most taxonomically complex groups. The UK flora DNA barcode reference library provides an important resource for many applications that require plant identification from DNA.

Highlights

The identification of plant species is vitally important for the monitoring, conservation and utilisation of biodiversity but is limited by the availability of taxonomic expertise
Generating an exhaustive national DNA barcode reference library can open up new avenues of research in ecology, evolution and conservation, yet few studies to date have created such a resource
Species level discrimination was highest with ITS2, the ability to successfully retrieve a sequence was lowest for this region

Summary

| INTRODUCTION

The identification of plant species is vitally important for the monitoring, conservation and utilisation of biodiversity but is limited by the availability of taxonomic expertise. Potential commercial applications involve using DNA barcoding to assess plant based products for sale, such as confirming the claimed identity of herbal medicines (Raclariu et al, 2018), verifying the geographic origin of honey (Prosser & Hebert, 2017; Saravanan et al, 2019), or checking the composition of plant species present in commercial tea preparations (de Boer et al, 2017; Stoeckle et al, 2011) Underpinning this diversity of applications are well-curated reference libraries, with associated voucher specimens and sample metadata (Hebert et al, 2003). Given our extensive use of herbarium material, we assess how the success of Sanger-based sequence recovery is affected by specimen age and by higher-level taxonomy; how the three markers rbcL, matK, and ITS2 vary in their ability to successfully recover a sequence, how the three markers vary in their species level discrimination and discuss their applicability for DNA metabarcoding studies

| MATERIALS AND METHODS

| RESULTS

| DISCUSSION

Findings

| Conclusions