One step closer to finally beating annosum root rot
Sequencing the genome of a member of the annosum family helps scientists understand how the infamous pathogen works.
Annosum root rot is no small inconvenience: it affects both spruce and pine and causes annual losses of EUR 50 million in Finnish forests. The fungus troubles coniferous forests in the whole of the northern hemisphere.
Full protection against annosum root rot has yet to be discovered, but the loop is tightening around it. As a result of along-term research project, the entire genome of the fungus has now been sequenced and published in the prestigious New Phytologist journal. The project was coordinated by the Swedish agricultural university SLU, and 52 researchers from all corners of the world participated. The University of Helsinki contributed through the efforts of Fred Asiegbu, professor of forest pathology, FiDiPro Professor Yong-Hwan Lee and Tommaso Raffaello, currently completing his dissertation.
The genome data can be used in important practical applications such as resistance studies or the development of new prevention measures.
"The genome sequence of the fungus helps us understand how the fungus affects the trees. Analysis of the genome also helps explain the fact that the pathogen has two ways of obtaining sustenance," explains Fred Asiegbu.
Annosum root rot can find nourishment either through rotting dead cells or by killing living cells. It destroys timber through its ability to use all the components of wood: lignin, cellulose and hemicellulose. Rotten timber cannot be used at sawmills. In addition, cellulose decay prevents the wood from being used in pulp or paper industry, and the decay of hemicellulose decreases its value for the chemical industry. When annosum root rot strikes, the timber is only good for firewood.
The polyporous fruiting bodies grow on dead roots of coniferous trees and are usually only revealed when the tree is felled. Spores are carried by wind onto the surface of fresh stumps. They begin to grow filaments that push into the stump and eventually to the surrounding trees through their roots.
"The number of airborne spores is the highest in the summer, which means that felling should be done in winter to prevent the disease from spreading," says Asiegbu.