The ITS Region Provides a Reliable DNA Barcode for Identifying Reishi/Lingzhi (Ganoderma) from Herbal Supplements

Summary

This research demonstrates a reliable DNA-based method for authenticating reishi mushroom supplements. The study found that while many supplements are labeled as containing Ganoderma lucidum, they actually contain the closely related species Ganoderma lingzhi. This finding has important implications for consumers and the supplement industry. Impacts on everyday life: • Helps ensure consumers get authentic reishi supplements they’re paying for • Provides a way to verify supplement quality and detect substitutions • Improves transparency in the herbal supplement industry • Protects consumers from potentially harmful ingredient substitutions • Enables better quality control standards for supplement manufacturers

Background

The dietary supplement industry is rapidly growing yet recent studies revealed up to 60% of supplements may have substituted ingredients, some of which can be harmful contaminants or additives. When ingredients cannot be verified morphologically or biochemically, DNA barcoding complemented with molecular phylogenetic analysis can be a powerful method for species authentication. Reishi (Ganoderma spp.) is one of the oldest herbal medicines in recorded history and represents approximately 2% of the herbal supplement industry.

Objective

To employ molecular phylogenetic analysis for species authentication of the commonly used fungal supplement reishi (Ganoderma lingzhi) by amplifying and sequencing the nuclear ribosomal internal transcribed spacer regions (ITS) with genus-specific primers.

Results

PCR of the samples produced single, strong amplification products in the expected size-range for Ganoderma. Both best-hit BLAST and molecular phylogenetic analyses clearly identified the presence of G. lingzhi DNA in all seven herbal supplements. Variation was detected in the ITS sequences among samples, but all herbal supplement samples fell within a large clade of G. lingzhi ITS sequences.

Conclusion

ITS-based phylogenetic analysis is a successful and cost-effective method for DNA-based species authentication that could be used in the herbal supplement industry for this and other fungal and plant species that are otherwise difficult to identify. The study demonstrated that the ITS region provides an efficient barcode for store-bought reishi herbal supplements.
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