Mitochondrial plastid DNA can cause DNA barcoding paradox in plants

Area of Science:

• Plant genomics
• Molecular evolution
• Bioinformatics

Background:

• Mitochondrial plastid DNA (MTPT) transfer from plastids to mitochondria is a known phenomenon in plants.
• The impact of MTPT on mitochondrial genome complexity and its role in DNA barcoding paradoxes are underestimated.
• Cynanchum wilfordii and C. auriculatum are indigenous medicinal herbs with significant economic and traditional value.

Purpose of the Study:

• To investigate the extent and impact of MTPT in Cynanchum species.
• To understand how MTPT contributes to mitochondrial genome complexity.
• To identify the potential of MTPT to cause DNA barcoding paradoxes and mis-authentication of botanical ingredients.

Main Methods:

• Assembly of organelle genomes for Cynanchum wilfordii and C. auriculatum.
• Comparative genomic analysis to identify MTPT regions.
• Evaluation of plastid barcoding markers for co-amplification of MTPTs.
• Analysis of MTPT dynamics across 81 plant species.

Main Results:

• Approximately 35% of ancestral plastid genomes were transferred to mitochondrial genomes in the studied Cynanchum species over the last 10 million years.
• Conserved MTPTs were co-amplified by some plastid barcoding markers, leading to a DNA barcoding paradox.
• Dynamic and lineage-specific MTPTs were identified, contributing to mitochondrial genome complexity and potential barcoding paradoxes in 81 plant species.
• Evidence of mis-authentication of botanical ingredients and taxonomic mis-positioning due to MTPT co-amplification.

Conclusions:

• MTPT significantly contributes to mitochondrial genome complexity in plants.
• The presence of MTPT can cause a DNA barcoding paradox, leading to inaccurate species identification and taxonomic classification.
• Development of DNA barcoding guidelines using multiple markers is crucial to prevent economically motivated adulteration and ensure accurate authentication of botanical ingredients.