Title: DNA Barcoding: Unsuccessful for Species Identification in Fragaria L. Authors
|Njuguna, Wambui -|
Submitted to: International Horticultural Congress
Publication Type: Abstract Only
Publication Acceptance Date: March 31, 2010
Publication Date: N/A
Interpretive Summary: DNA barcoding is a technique designed for identification of species using a short DNA sequence. This technique can put a species name on unknown organisms. In 2005, two DNA sequences were recommended as universal barcodes for species identification in plants. The USDA, National Clonal Germplasm Repository in Corvallis, Oregon, has about 24 strawberry species. The aim of this study was to test four DNA sequences as DNA barcodes for verifying strawberry species. None of these sequences, singly or in combination, could identify the strawberry species. Therefore, DNA barcoding using the recommended universal sequences was not a successful technique for identification of strawberry species – and maybe inappropriate in other plant groups.
Technical Abstract: The USDA-ARS National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, maintains more than 1500 of Fragaria accessions representing approximately 24 species collected from 37 countries. Species designation currently depends on the published species descriptions which depend on geographical location and morphological traits that exhibit limited variation. Our objective was to assess if a simple DNA-based technique like DNA barcoding could verify the identity of Fragaria species. Four potential barcoding regions were tested in Fragaria. They consisted of the nuclear ribosomal internal transcribed spacer (NrITS) and three chloroplast regions (psbA-trnH spacer; IRB11 [YCF2/ORF2280 3' to ORF 79] and IRB14 [ndhB 5' exon to rps 7, 5' end]). IRB11 and IRB14 are located in the inverted repeat region B (IRB) of the chloroplast genome. The ‘barcoding gap’, between within species and between species variation, was absent preventing successful identification of Fragaria species. Cluster analysis using NrITS supported F. mandschurica as the maternal donor to the octoploids. Three diploid Fragaria clades (X, Y and Z) were identified using NrITS, while the chloroplast psbA-trnH contained little variation. The psbA-trnH spacer could only identify F. bucharica and F. nilgerrensis due to characteristic deletions in this chloroplast region. However, none of these sequences, singly or in combination, could identify each of the Fragaria species. Therefore, DNA barcoding using universal sequences is not an adequate technique for species identification in Fragaria. orldwide peach research community.