Discriminating plants using the DNA barcode rbcLb: an appraisal based on a large data set.

Area of Science:

• Botany
• Molecular Biology
• Genetics

Background:

• The ideal DNA barcode for plants is still under investigation.
• The candidate barcode rbcL has faced skepticism regarding its effectiveness.
• Variability of rbcL across all plant groups and its barcode performance remain underexplored.

Purpose of the Study:

• To evaluate the performance of rbcL regions as DNA barcodes for plant species discrimination.
• To compare the variability and discriminatory power of rbcLa and rbcLb regions.
• To identify a potentially universal plant DNA barcode.

Main Methods:

• Analysis of all available rbcL sequences in GenBank.
• Design of universal and plant group-specific primers for rbcLb amplification.
• Testing the performance of rbcLa and rbcLb using BLAST for identification and discrimination.

Main Results:

• The rbcLb region demonstrated higher variability compared to the rbcLa region.
• Both regions successfully identified most families and genera, but species identification rates varied significantly (24.58–90.89%).
• rbcLb generally outperformed rbcLa, especially in angiosperms, showing higher species discrimination rates.

Conclusions:

• The rbcLb region exhibits superior performance as a plant DNA barcode compared to rbcLa.
• rbcLb offers better applicability across diverse plant groups, including lower and higher plants.
• rbcLb is proposed as a universal plant barcode due to its variability, primer universality, and discriminatory power.