Not all bad: Gyromitrin has a limited distribution in the false morels as determined by a new ultra high-performance liquid chromatography method

ABSTRACT

Gyromitrin (acetaldehyde N-methyl-N-formylhydrazone) and its homologs are deadly mycotoxins produced most infamously by the lorchel (also known as false morel) Gyromitra esculenta, which is paradoxically consumed as a delicacy in some parts of the world. There is much speculation about the presence of gyromitrin in other species of the lorchel family (Discinaceae), but no studies have broadly assessed its distribution. Given the history of poisonings associated with the consumption of G. esculenta and G. ambigua, we hypothesized that gyromitrin evolved in the last common ancestor of these taxa and would be present in their descendants with adaptive loss of function in the nested truffle clade, Hydnotrya. To test this hypothesis, we developed a sensitive analytical derivatization method for the detection of gyromitrin using 2,4-dinitrobenzaldehyde as the derivatization reagent. In total, we analyzed 66 specimens for the presence of gyromitrin over 105 tests. Moreover, we sequenced the nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode) and nuc 28S rDNA to assist in species identification and to infer a supporting phylogenetic tree. We detected gyromitrin in all tested specimens from the G. esculenta group as well as G. leucoxantha. This distribution is consistent with a model of rapid evolution coupled with horizontal transfer, which is typical for secondary metabolites. We clarified that gyromitrin production in Discinaceae is both discontinuous and more limited than previously thought. Further research is required to elucidate the gyromitrin biosynthesis gene cluster and its evolutionary history in lorchels.

KEYWORDS:

• 2,4-Dinitrobenzaldehyde
• Discinaceae
• Gyromitra spp
• Hydnotrya spp
• Pezizales
• Schiff bases
• UHPLC-DAD analysis

ACKNOWLEDGMENTS

We extend our gratitude to all the people who collected and donated specimens, which greatly augmented this project: Leah Bendlin, Eric Chandler, Jen Chandler, Jonathan Frank, Igor Khomenko, Kitty Lundeen-Ness, Bee Marcotte, Steve Ness, Dave Ramos, Jon Shaffer, Huafang Su, Garrett Taylor, Jud Vanwyk, and Jeff Volpert. We also thank the fungarium curators, collection managers, and assistants who supported this research by loaning specimen vouchers and cultures: Dr. A. Elizabeth Arnold, Joseph Myers, and Ming-Min Lee (ARIZ); Dr. Matthew Smith, Dr. Rosanne Healy, and Benjamin Lemmond (FLAS); and Patricia Rogers and Dr. Alison Harrington (MICH). Michelle Orozco-Quime’s work in trialing gyromitrin spot tests is much appreciated. Vavřinec Klener provided a helpful translation of a section of Kubička (1966). Taylor M. Tai provided thoughtful editorial advice on earlier drafts of the manuscript.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00275514.2022.2146473.

Additional information

Funding

The strains provided by Dr. A. Elizabeth Arnold were collected with support from the National Science Foundation under grants DEB-1045766 and DEB-1541496, with additional support from the University of Arizona’s College of Agriculture and Life Sciences and U.S. Department of Agriculture National Institute of Food and Agriculture (USDA NIFA) awards ARZT-1361340-H25-242 and ARZT-1259370-S25-200. This research was supported by the Michigan Translational Research and Commercialization (MTRAC) Innovation Hub for AgBio and the Canadian Institute for Advanced Research (CIFAR). A.T. received funding from the University of Michigan Biological Science Initiative. T.Y.J. is a fellow of the CIFAR research program “Fungal Kingdom: Threats & Opportunities.” The authors report there are no competing interests to declare.