DNA barcode trnH-psbA is a promising candidate for efficient identification of forage legumes and grasses

<strong>Objective</strong> Grasslands are widespread ecosystems that fulfil many functions. Plant species richness (PSR) is known to have beneficial effects on such functions and monitoring PSR is crucial for tracking the effects of land use and agricultural management on these ecosystems. Unfortunately, traditional morphology-based methods are labor-intensive and cannot be adapted for high-throughput assessments. DNA barcoding could aid increasing the throughput of PSR assessments in grasslands. In this proof-of-concept work, we aimed at determining which of three plant DNA barcodes (<em>rbcLa</em>, <em>matK</em> and <em>trnH-psbA</em>) best discriminates 16 key grass and legume species common in temperate sub-alpine grasslands. <strong>Results</strong> Barcode <em>trnH-psbA</em> had a 100% correct assignment rate (CAR) in the five analyzed legumes, followed by <em>rbcLa </em>(93.3%) and <em>matK</em> (55.6%). Barcode <em>trnH-psbA</em> had a 100% CAR in the grasses <em>Cynosurus cristatus</em>, <em>Dactylis glomerata</em> and <em>Trisetum flavescens</em>. However, the closely related <em>Festuca, Lolium </em>and <em>Poa</em> species were not always correctly identified, which led to an overall CAR in grasses of 66.7 %, 50.0% and 46.4% for<em> trnH-psbA</em>, <em>matK</em> and <em>rbcLa</em>, respectively. Barcode <em>trnH-psbA</em> is thus the most promising candidate for PSR assessments in permanent grasslands and could greatly support plant biodiversity monitoring on a larger scale. <strong>Content of data file</strong> This data file contains all raw data obtained during the study. The full information on the project can be found on the BOLD database (http://www.boldsystems.org/index.php/Public_SearchTerms) using the search term SWFRG