An international collaboration led by the research group of László Nagy from the ELKH Biological Research Centre in Szeged (BRC) has recently published a paper in Nature Microbiology that sheds light on previously unknown aspects of plant pathogenic Armillaria fungi. Researchers from BRC, the Joint Genome Institute in the USA, the University of Sopron, and Western Sydney University in Australia, among others unveiled the genetic background of the plant pathogenic and biomass-degrading abilities of Armillaria fungi.
The honey fungus belongs to the oldest and largest living organisms on Earth, with some colonies estimated to be around 8000 years old and covering nearly 1000 hectares in size. However, it is not their age or size that is the most crucial fact, but rather their pathogenic ability. Honey fungi are among the most destructive pathogens in temperate zone forests, capable of wiping out entire forests in certain areas. Their surviving structures in the soil, known as rhizomorphs, help them remain alive for extended periods, hindering reforestation efforts.
Extensive colonies of Armillaria mellea honey fungus species in a decaying forest area.
(Photo by Virág Tomity)
The research conducted with funds coming from the Lendület, ERC and previous GINOP programs, includes new genome sequencing, bioinformatics analyses, and extensive gene expression and molecular biology investigations. In the recently published study, the researchers were the first to explain several surprising characteristics of honey fungi, providing insights into important genes involved in infecting and colonizing living plants. These fungi efficiently decompose both living and dead woody plant parts through their extracellular enzyme systems, offering prospects in biofuel production. The researchers also uncovered the enzymatic systems involved in plant biomass degradation and the unique features associated with this process/or and the enzymatic systems of the honey fungi.
The experiments conducted by Jonathan Plett, the partner from Australia constituted an important part of the project, in which researchers expressed the presumed pathogenicity factors of Armillaria species in plants. These experiments demonstrated that certain secreted Armillaria proteins cause the death of plant cells, thus contributing to plant colonization. Since genetic modifications do not currently work in Armillaria species, such experiments play a crucial role in unraveling the genetic background of pathogenicity.
The spread of Armillaria species is facilitated by underground clonal propagules, called rhizomorphs, through which the fungus can travel several meters underground in search of new host plants.
(Photo by Neha Sahu)
Following the highly acclaimed previous paper of the collaboration, the recently published study marks a significant advance in the future fight against Armillaria species. It identifies numerous crucial target genes and mechanisms that can serve as the foundation for further research. Additionally, the publication represents the primary work of Neha Sahu, a PhD student at BRC, who successfully concluded her research at the institute with this first-authored paper, moving on to The Sainsbury Laboratory in the UK to continue the research.