Studies in Gyromitra II: cryptic speciation in the Gyromitra gigas species complex; rediscovery of G. ussuriensis and G. americanigigas sp. nov

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

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.

Next-Generation Sequencing of Ancient and Recent Fungarium Specimens

Fungaria are an unmatched resource for providing genetic data from authoritative, taxonomically-correct fungal species, especially type specimens. These specimens serve to anchor species hypotheses by enabling the correct taxonomic placement of taxa in systematic studies. The DNA from ancient specimens older than 30 years is commonly fragmented, and sometimes highly contaminated by exogenous, non-target fungal DNA, making conventional PCR amplification and Sanger sequencing difficult or impossible. Here, we present the results of DNA extraction, PCR amplification of the ITS2 region, and Illumina MiSeq Nano sequencing of nine recent and 11 ancient specimens, including seven type specimens. The taxa sampled included a range of large and fleshy, to small and tough, or small, melanized specimens of Discina, Gyromitra, Propolis, Stictis, and Xerotrema, with a culture of Lasiosphaeria serving as a positive control. DNA was highly fragmented and in very low quantity for most samples, resulting in inconclusive or incorrect results for all but five samples. Taxonomically-correct sequences were generated from the holotype specimens of G. arctica, G. korshinskii, and G. leucoxantha, from the neotype of G. ussuriensis, and from the positive control. Taxonomic assignments were confirmed through morphology, top BLASTn hits, and maximum likelihood phylogenetic analyses. Though this study was not cost-effective due to the small number of samples submitted and few generating correct sequences, it did produce short DNA barcode fragments for four type specimens that are essential for their correct taxonomic placement in our ongoing systematic studies.