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Escaping Introns in COI Through cDNA Barcoding of Mushrooms: Pleurotus as a Test Case

Summary

This research developed a new method for identifying different species of oyster mushrooms using genetic markers. Instead of using traditional DNA analysis, which can be complicated by extra genetic material in mushrooms, the researchers used RNA-based methods to get cleaner results. This advancement helps scientists more accurately identify different mushroom species. Impacts on everyday life: • Improved ability to verify mushroom species identity for food safety • Better quality control for commercial mushroom cultivation • More accurate identification of mushroom species in natural environments • Enhanced ability to detect and track mushroom diversity • Potential applications in authenticating medicinal mushroom products

Background

DNA barcoding uses short, standardized DNA fragments for rapid species identification. While a 648-bp segment of the COI gene is the standard barcode for animals, its use in mushrooms is complicated by frequent large introns. As a result, ITS has been adopted as the standard DNA barcode for mushrooms despite several limitations.

Objective

This study aimed to test the effectiveness of using newly designed primers coupled with cDNA analysis to examine COI sequence diversity in six species of Pleurotus mushrooms and compare these results with ITS sequences. The research sought to evaluate amplification success, sequence variation, and primer design effectiveness for COI as a potential complementary barcode marker for mushrooms.

Results

Interpretable ITS sequences were recovered from 20 of 24 specimens, with lengths varying from 592-625 bp. COI sequences were recovered from all specimens, though only partial COI-3′ sequences were obtained from P. giganteus. Both markers readily distinguished between species with moderate to strong support. The cDNA approach successfully avoided intron complications that typically hinder COI sequencing in mushrooms. COI showed 76.8% conserved sites while ITS showed 37.7% conserved sites.

Conclusion

The study demonstrates that COI can be an effective additional barcode marker for fungi when using a cDNA-based approach, particularly in cases where ITS is unsuitable. Both ITS and COI showed similar capacity to delimit Pleurotus species, with complementary strengths. The success of COI in discriminating these taxa justifies larger-scale efforts to validate its effectiveness as a barcode for Pleurotus and other mushrooms.
  • Published in:Ecology and Evolution,
  • Study Type:Laboratory Research,
  • Source: 10.1002/ece3.3049
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