Scientists exploring the forests of Yunnan, China, have discovered an extraordinary giant fungus that is challenging previous assumptions about how large certain fungi can grow. The newly identified species, Dianjunus rex, produces upright reproductive structures that can reach 50 cm (20 inches) in height and weigh as much as 2.2 kg (4.9 pounds). These are the largest known fruiting bodies among fungi belonging to the phylum Ascomycota.
"This remarkable species represents a new fungal family, Dianjunaceae, and provides a rare window into the evolution of extreme fungal body forms," said 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, published in Frontiers in Fungal Biology. "The discovery illustrates how much fungus biodiversity remains to be discovered in East Asian forests." A Giant Fungus Hidden in China's Forests Researchers from the Kunming Institute of Botany encountered the unusual fungus while surveying several forest environments in Yunnan. Their fieldwork included temperate coniferous forests near Damaidi and Yipinglang, along with tropical rainforest near Nanbang.
The team spotted unusually large, whitish reproductive structures, known as 'stromata', growing from the woody roots of Chinese cork oak trees. These structures emerged from the rhizosphere, the region of soil surrounding plant roots, and appeared to belong to an unidentified member of the ascomycete fungi. Ascomycetes make up the largest major group of fungi, with more than 64,000 recognized species.
Unlike familiar mushrooms, these fungi do not produce true mushroom structures. Instead, they generate spores within tiny sac-like structures found inside or on the surfaces of their fruiting bodies. To investigate the discovery, the scientists collected samples and preserved reference specimens in the Kunming Institute of Botany's collections.
They also cultivated spores under laboratory conditions to examine the fungus's physical characteristics and sequenced its genome, including its protein-coding genes. Meet D-Rex, a Record-Breaking Fungal Giant The genetic analysis, together with a close examination of the fungus's physical features, revealed that the discovery represented much more than a previously unknown species. It was sufficiently different from known fungi to require the creation of a new genus and an entirely new family (Dianjunaceae) within the order Xylariales.
The researchers named the species Dianjunus rex, drawing inspiration from its impressive size and the ancient Dian kingdom. Its nickname, 'D-rex', reflects its exceptional stature among related fungi. Its closest known relative is Graphostroma platystoma, a fungus that grows on dead hardwood throughout the Northern Hemisphere.
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