Affirmation of DNA barcoding as a poweful tool in cataloguing medicinal and aromatic plants in mediterranean forests
Author(s)
Laiou, Angeliki
Date Issued
May 27, 2013
Type
Doctoral Thesis
Abstract
From the pre-historic era, men have been using plants as medicine and in recent years,
medicinal and aromatic plants (MAPs) harvested from the wild still remain of immense importance.
MAPs are clearly an important global resource in terms of healthcare but they are also an important
economic resource. Consequently, MAPs are an ideal case for developing DNA barcodes. In this
doctorate thesis, more than 100 specimens were sampled in different biogeographic regions through
Italy and Greece (three provenances from Italy and one from Greece) of each country including also
some representatives from other countries for comparison. Thus, 38 medicinal and aromatic plant
species have been collected and being analyzed, derived from 22 genera, with a total number of 30
different provenances belonging to 17 families.
We used “core barcode” for land plants rbcL and matK, and tested trnH-psbA as additional
marker. Each marker was amplified with the universal primer pairs. RbcL displayed 100%
amplification success, followed by trnH-psbA 98%, while matK was unable to amplify some certain
plant groups (overall amplification success of 91).
Species discrimination success was attempted using sequence character states (Blastclust),
presence of barcoding-gap (uncorrected p-distances), species monophyly through inference of
RAxML dendrogram and assessment discrimination using GenBank. These approaches return
similar results in the discrimination level of species using all combined markers.
The trnH-psbA region showed the highest values of genetic variability; however this
divergence did not allow reliable alignment across all sequences and consequently contributed to
the absence of barcoding gap.
Regarding the results retrieved from Genbank submissions, the lowest percentage of
molecular data was retrieved surprisingly by MatK (37% of the species in GenBank), even if it is
considered one of the most recommended core-barcodes with the highest discriminatory power. The
majority of data were produced by trnH-psbA (65% of the species in GenBank) showed a good
coverage, highlighting that this marker, beyond the core barcode, is becoming the most widely used
plastid region.
On the whole, conserving medicinal and aromatic plants biodiversity should be given a
serious attention as well as the development of an integrated DNA database. An important
limitation DNA barcoding potential users may actually meet is related with a yet incomplete
reference list in the database as well as the common used similarity methods in these databases are
prone to errors. Moreover, the use of a fourth marker could be necessary to obtain adequate
discriminatory power. In conclusion, this doctorate thesis highlights the utility of DNA barcoding as
a promising tool in providing a practical and standardized identification of medicinal and aromatic
plants thus contributing to the conservation and the trade control of these valuable plant resources.
Additional information
Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale
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