Les, Donald , Benoit, Lori , Lopez Peredo, Elena , King, Ursula .
"Now that's not Najas!" A genetic marker for the water sprites (Najas; Hydrocharitaceae).
Increasingly, procedures to facilitate plant identification have become sought after, especially as the level of botanical expertise dwindles while infestations of invasive species multiply. Aquatic plants are particularly difficult to identify, even to genus, as they often are found in vegetative condition where few distinctive characteristics are apparent to the casual observer. In such cases, the identification of individual species using a characteristic 'DNA barcode' region has been offered as one potential solution, but has been the subject of some debate, particularly with respect to providing the most effective and distinctive genetic region for analysis. At best, identifications using DNA barcodes still involve a somewhat lengthy sequencing protocol and the availability of expensive technical equipment. As we evaluated next-generation (454) genomic DNA sequence data for Najas flexilis, we discovered one cpDNA region, which differed by a simple 3 bp (AGA) insert relative to a large number (>100) of angiosperm family sequences deposited in GenBank, including one from the closely-related Araceae. The insert occurs within the LSC region of the chloroplast genome within a relatively conserved 28 bp spacer between the psaA and psaB genes. To evaluate the phylogenetic potential of this marker, we developed a PCR/RFLP method, which enabled us to characterize more explicitly the extent of the insert by rapidly surveying nine other Najas species as well as a representative sample of 24 other alismatid genera from 10 families: Alismataceae (Alisma, Astonia, Sagittaria), Aponogetonaceae (Aponogeton), Butomaceae (Butomus), Cymodoceaceae (Halodule, Syringodium, Thalassodendron), Hydrocharitaceae (Blyxa, Egeria, Elodea, Enhalus, Hydrilla, Hydrocharis, Ottelia, Stratiotes, Thalassia, Vallisneria), Juncaginaceae (Triglochin), Posidoniaceae (Posidonia), Potamogetonaceae (Potamogeton), Ruppiaceae (Ruppia) and Zosteraceae (Phyllospadix, Zostera). Our survey indicated that this genetic marker was not unique to Najas flexilis; however, it was restricted to the Najas species analyzed. Thus, this coincidental discovery from 454 sequence data has provided a simple, rapid, PCR-based technique that confidently separates Najas species from superficially similar genera such as Egeria, Elodea, Hydrilla, and Potamogeton.
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1 - University Of Connecticut, Ecology & Evolutionary Biology, 75 N. Eagleville Road, Unit 3043, Storrs, CT, 06269-3043, USA
2 - Trinity College Dublin, Biology, Dublin, Ireland
aquatic plant identification
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell C/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 2:15 PM