Armillaria Species: Biological Complexity, Bioactive Metabolites and Molecular Foundations for Medicinal and Agricultural Applications

Armillaria is a genus of macrofungi with high ecological, biological, medicinal, and edible value. As facultative plant pathogens and nutritional symbionts, Armillaria species support the growth of valuable medicinal plants including Gastrodia elata and Polyporus umbellatus. They also exhibit unique traits such as exceptional longevity, widespread clonal expansion, rhizomorph formation, and bioluminescence, making them a valuable model for studying fungal ecology, symbiosis, specialized metabolism, and applied research. This review summarizes recent progress in Armillaria research, covering biological characteristics, nutritional components, bioactive constituents, species identification, genomic resources, and biosynthetic pathways. We discuss advances in artificial cultivation and the regulatory roles of exogenous phytohormones in mycelial and rhizomorph development. The nutritional value of fruiting bodies is highlighted, with a focus on key pharmacologically active metabolites such as protoilludane-type sesquiterpenes and polysaccharides. We also review multilocus phylogenetic analysis, comparative genomics, and the biosynthetic gene clusters of melleolides and bioluminescence, which have improved understanding of Armillaria evolution and functional differentiation.