Ancient DNA extraction methods for herbarium specimens: When is it worth the effort?

Area of Science:

• Molecular Biology
• Botany
• Genetics

Background:

• Herbarium specimens are valuable resources for molecular systematic studies.
• DNA extraction from preserved plant material is challenging due to low DNA yield and quality.

Purpose of the Study:

• To compare the efficacy of a standard DNA extraction kit versus an ancient DNA (aDNA) protocol for herbarium specimens.
• To determine the optimal method for obtaining high-quality DNA for next-generation sequencing from diverse plant collections.

Main Methods:

• Compared Qiagen DNeasy Plant Mini Kit with the PTB-DTT aDNA extraction method.
• Utilized plant genera *Xanthium* and *Salix* spanning two centuries.
• Assessed DNA yield, quality, and sequencing success using library preparation and target-enrichment.

Main Results:

• The PTB-DTT method yielded significantly higher DNA quantity and quality than the Qiagen kit.
• Sequencing results from the Qiagen kit were comparable to PTB-DTT when DNA yield and quality thresholds were met.
• Successfully sequenced DNA from 200-year-old herbarium samples.

Conclusions:

• Standard DNA extraction kits may suffice for younger herbarium specimens.
• aDNA extraction methods are recommended for old and valuable herbarium specimens to meet next-generation sequencing requirements.