DNA Barcoding Study of Representative Thymus Species in Bulgaria

Area of Science:

• Botany
• Molecular Biology
• Genetics

Background:

• The genus Thymus, particularly in Bulgaria, presents significant taxonomic challenges due to its diversity and endemism.
• Existing taxonomic schemes for Thymus species are primarily based on morphological traits, which can be ambiguous.

Purpose of the Study:

• To investigate the taxonomic relationships of eleven naturally occurring Thymus species in Bulgaria.
• To evaluate the effectiveness of four DNA barcoding markers (matK, rbcL, trnH-psbA, and ITS) in species discrimination and phylogenetic analysis.

Main Methods:

• DNA was extracted from eleven Thymus species found in Bulgaria.
• Four standard DNA barcoding markers (matK, rbcL, trnH-psbA, and ITS) were amplified and sequenced.
• Phylogenetic analyses were conducted to assess species relationships and genetic diversity.

Main Results:

• The rbcL marker demonstrated the lowest species-discriminating power among the tested markers.
• The matK, trnH-psbA, and ITS markers provided results more consistent with existing morphological classifications, though not entirely straightforward.
• Discrepancies were observed, with morphologically distinct species sometimes clustering together and closely related species appearing genetically separate.

Conclusions:

• DNA barcoding offers valuable insights into Thymus taxonomy but requires careful marker selection and interpretation, especially for complex genera.
• The genetic data underscore the need for comprehensive taxonomic studies of the diverse and endemic Thymus flora in Bulgaria.
• Further research is recommended to resolve existing taxonomic uncertainties within the genus Thymus using molecular approaches.