Lingzhi Mushroom’s Jumping Mitochondrial Genomes Expose a Mislabeling Crisis

The lingzhi mushroom has been called the mushroom of immortality for more than two thousand years. Ancient Chinese texts classified it as a superior drug, one that could calm the spirit, resist aging, and prolong life. Today it is a billion-dollar industry spanning medicine, food, and nutraceuticals, and China has recently moved to formally recognize it as a substance used for both medicinal and dietary purposes. Yet behind the mystique sits an embarrassingly practical problem: nobody has been entirely sure which fungus is actually in the bag. A new large-scale genomic study has now sequenced the mitochondrial genomes of 181 lingzhi strains from across China, and the results reveal both a widespread identity crisis in the commercial market and a surprisingly elegant solution written in the fungus’s own DNA.

The research, published in the journal IMA Fungus, represents the first pan-mitogenomic analysis of Ganoderma lingzhi, the species formally separated from its European relative Ganoderma lucidum only in 2012. The team collected 151 cultivated Ganoderma strains from growers, culture collections, research institutions, and companies across China, most of them claimed to be G. lingzhi, and combined them with 30 publicly available whole-genome sequencing datasets. From each sample they assembled complete mitochondrial genomes, the small circular DNA molecules that fungi, like all eukaryotes, maintain inside their energy-producing organelles. What they found when they compared the labels against the sequences was striking: 19 of the 151 collected strains did not match their claimed identity. Thirteen strains sold or maintained as G. lingzhi were not lingzhi at all, while six strains thought to be something else turned out to be genuine lingzhi.

That misidentification rate, roughly one in eight, is not a trivial bookkeeping error. The authors point out that lingzhi strains are notoriously difficult to tell apart by eye, particularly at the mycelial stage, when the fungus exists as threadlike filaments lacking any distinctive taxonomic features. The standard molecular tool, sequencing of the internal transcribed spacer, or ITS, region of nuclear DNA, works well for separating species but loses its discriminating power within a species. Commercial strain names frequently do not correspond to actual taxonomy, which destabilizes quality and yield in cultivation, confuses consumers, and threatens the sustainable development of an industry that has been expanding rapidly since lingzhi’s dual-use medicinal and food designation. The mislabeled strains in the study came from every corner of the supply chain: seven from culture collections, four from growers, and eight from research institutions or companies.

The mitochondrial genomes themselves turned out to be the real story. Across 157 confirmed G. lingzhi samples, the mitogenomes ranged from 49,233 to 70,498 base pairs, the smallest in the entire Ganoderma genus, whose members can stretch past 100,000 base pairs. That is a difference of more than 21,000 base pairs within a single species, a staggering amount of structural variation for genomes that carry essentially the same genes. Every lingzhi mitogenome contained the same conserved toolkit: 15 protein-coding genes involved in energy metabolism, two ribosomal RNA genes, and 23 to 24 transfer RNA genes. The coding regions barely varied at all, spanning only 20,062 to 20,472 base pairs. So where was all the extra DNA hiding?

The answer is introns, the interrupting sequences that splice themselves out of genes, and in lingzhi they behave less like furniture and more like squatters. The team identified 20 distinct mitochondrial introns whose presence or absence was wildly dynamic across the population. Individual strains carried anywhere from 7 to 16 of them, and their combined length ranged from 8,270 to 24,374 base pairs. Correlation analysis delivered the smoking gun: total intron length explained nearly all mitogenome size variation, with an R-squared value of 0.9581. Nineteen of the twenty introns encode homing endonucleases, enzymes of the LAGLIDADG or GIY-YIG families that act as molecular hitchhikers, cutting DNA at specific sites to coax the cell into copying the intron that carries them into new locations. These are mobile genetic elements, jumping genes in the most literal sense, and their constant gains and losses are the primary engine of genomic diversity within the species.

One intron stood out as genuinely strange. The intron lodged in the large ribosomal RNA gene at position 2831, dubbed rnLP2831, encodes three open reading frames, and one of them carries a family B DNA polymerase domain rather than a homing endonuclease. DNA polymerases are replication enzymes, not genome-hopping weapons, and their presence inside a fungal intron is rare. The authors propose that this gene likely did not originate in the intron at all but arrived through the integration of a mitochondrial plasmid, a small accessory DNA molecule that fungi sometimes harbor and that often carries its own polymerase for self-replication. If correct, it means the lingzhi mitogenome is not just absorbing mobile introns but occasionally swallowing entire foreign replicons, adding another layer of plasticity to an already fluid genome.

When the researchers clustered the 157 samples by their intron fingerprints, a clean pattern emerged: two major groups, one containing 107 strains and the other 50. Three introns, cox2P228, nad5P426, and cox1P1305, were present in every single sample, marking them as ancient acquisitions fixed in the common ancestor of the modern population. Six others were perfectly lineage-specific, found only in one group or the other, suggesting they were acquired after the two lineages diverged. The rest showed messier distributions, which the authors attribute to incomplete lineage sorting, recent horizontal transfer between strains, or independent losses, and they caution that a single intron’s presence is too volatile a trait to infer deep evolutionary history on its own. But the two-group structure held up independently when they built a phylogenetic tree from the 15 conserved protein-coding genes, confirming that lingzhi strains genuinely split into two intraspecific subgroups.

The comparative genomics across the wider genus added evolutionary context. Gene order was remarkably conserved across 14 of 17 Ganoderma species examined, following a single canonical arrangement, with only G. tsugae and G. calidophilum showing minor inversions and G. leucocontextum displaying extensive rearrangement. Ka/Ks analysis, which compares nonsynonymous to synonymous substitution rates, showed that all 15 core protein-coding genes sit well below neutral expectations, the signature of purifying selection relentlessly pruning harmful mutations. The phylogenetic tree confirmed the monophyly of G. lingzhi as a distinct clade, sister to G. pseudoferreum and G. multipileum, and independently corroborated the misidentification findings through a second line of genetic evidence.

The practical payoff is a molecular fingerprinting system the authors call intron presence/absence variation profiling. By recording which of the 20 introns each strain carries, the team defined 30 unique mitochondrial haplotypes, effectively DNA barcodes for individual lingzhi strains. Because mitochondrial DNA is haploid, abundant in high copy numbers, and inherited without recombination, these haplotypes offer a stable, cheap, and highly discriminatory marker where ITS sequencing falls short. The authors envision the system serving as a benchmark for strain authentication, intellectual property protection, varietal traceability, and breeding programs, directly addressing the synonymy and misnaming problems that have plagued the industry. In a market where a mislabeled strain can mean the difference between a potent medicinal product and an inert one, a barcode that cannot lie may be the most valuable thing the mushroom of immortality has produced in two thousand years.

Subject of Research: Pan-mitogenomic analysis of Ganoderma lingzhi revealing intron-driven genomic variation and strain misidentification

Article Title: Insights into intraspecific variation and genotyping of Ganoderma lingzhi through pan-mitogenome analysis

Article References: Li, J., Zhang, C., Ni, Y., Sun, L., Cheng, X., & Liu, C. (2026). Insights into intraspecific variation and genotyping of Ganoderma lingzhi through pan-mitogenome analysis. IMA Fungus, 17, Article e184941. https://doi.org/10.3897/imafungus.17.184941

Image Credits: AI Generated

DOI: 10.3897/imafungus.17.184941

Keywords: Ganoderma lingzhi, mitogenome, introns, homing endonucleases, strain misidentification, DNA barcoding, fungal genomics, medicinal mushroom, phylogenetics, pan-genomics, mitochondrial haplotypes, purifying selection