An international team of scientists has discovered a gigantic new fungus species deep within the forests of Yunnan Province in China, according to research published in Frontiers. Formally named Dianjunus rex and nicknamed “D-rex” by researchers, the organism produces vertical fruiting bodies reaching up to 50 centimeters in height and weighing up to 2.2 kilograms. This scale makes it the largest known species within the phylum Ascomycota, surpassing previous record-holders that typically grew no taller than 20 to 30 centimeters.
Uncovering Dianjunus Rex in Yunnan
Fieldwork was conducted across multiple locations in Yunnan Province, with collections taking place near Damaidi and Yipinglang in temperate coniferous forests, and near Nanbang in a tropical rainforest. Scientists found the pale, whitish fruiting structures emerging from the rhizosphere, specifically growing on the woody roots of Chinese cork oak. Because of its distinct genetic makeup and unique features, researchers classified the organism not only as a new species and genus, but also established an entirely new family named Dianjunaceae within the order Xylariales.
Tracing Evolutionary Origins to the Dinosaur Extinction
Using a molecular clock technique to compare the genome of D. rex with the DNA of hundreds of other fungi with well-documented timelines, the research team estimated that the Dianjunaceae lineage arose approximately 65 million years ago. This timing closely follows the Cretaceous-Paleogene mass extinction event triggered by the Chicxulub asteroid impact. NDTV reported that the discovery offers insight into how life adapted and bounced back in ancient ecosystems.
Dr. Indunil C. Senanayake, an associate professor at the Germplasm Bank of Wild Species of the Kunming Institute of Botany in China and corresponding author of the study, noted that the environmental disruption following the mass extinction caused forests to experience dramatic changes, including the sudden availability of vast amounts of dead plant material. For wood-associated decomposing fungi, such ecological disruption may have created new opportunities. Ascomycetes within the order Xylariales are known to produce enzymes capable of breaking down lignin, the organic polymer that gives wood its structure, allowing them to consume dead wood efficiently.
Scientific Analysis and Unresolved Questions
Researchers hauled collected samples back to the lab, cultured their spores, and performed genetic analyses. Genomic comparisons revealed that the closest known relative to D. rex is Graphostroma platystoma, a gummy, black-tar-like fungus that grows on dying tree limbs and hardwood across the northern hemisphere. Investigators also found that D. rex produces several carbohydrate-active enzymes suspected to help break down tough plant matter with low metabolic maintenance required.
Regarding its towering stature, researchers suspect that a fruiting body rising above surrounding vegetation and forest debris could aid in wind-based spore dispersal in dense forests. However, building such a large structure requires substantial energy investment, indicating this strategy likely evolved only where ecological benefits outweighed costs. Despite these insights, several questions remain open. The study did not map the full extent of the fungus’s underground mycelial network, and the exact connection between the dinosaur extinction event and the evolution of the fungus remains hypothetical, with certain evolutionary estimates spanning a wider timeframe that covers periods both before and after the extinction.
