Wood-decay fungus#White rot

As a white rot (also Korrosionsfäule ) the process of lignin degradation in woody plants is called by fungi. This type of wood rot is to find Agaricomycetes only under the stand fungi of the class. White rot is the only known way by which organisms decompose lignin and related compounds and can use for their metabolism. Macroscopic signs of white rot are especially the whitening of the affected wood its defibration, and a concomitant loss of stability. The white rot necessary for physiological bases - including the production of the enzyme laccase - were probably the first time towards the end of the Carboniferous ( around 300 million years ago) to. At the same time, the deposition of lignin took in the form of today's coal greatly. The advent of white rot is therefore seen as a cause for this decline. From an economic standpoint wood white-rot fungi are pests because they damage trees suitable for timber and already can devalue harvested timber.

History and symptoms

The wood destruction can occur even in the living trunk, especially on hardwood. White rot fungi are capable of cellulose, hemicellulose and lignin to reduce. A distinction is made between selective ( successive ) and simultaneous degradation. In the selective white rot lignin (and hemicellulose ) are initially more degraded than cellulose. This affects the wood rather bright / white. The simultaneous white rot is characterized by the simultaneous reduction of all three Zellwandkomponeten, making the wood appear rather darker. In contrast to the white rot brown rot fungi destroy mainly the cellulose fraction.

In a white-rot disease, the wood structure remains largely intact, but the wood is brighter, lighter, more fibrous and foxed. The result is a uniform whitish- gray discoloration, the wood loses its luster. Characteristic are dark lines which delimit the infested from the healthy parts. These so-called demarcation lines allow the fungus to regulate the moisture in the wood. In the final stage the wood is " spongy ", often with a marble-like strips.

White rot requires livelihoods high moisture content and is to be found except on the living tree and in storage timber. In buildings white rot may occur, for example in the area of damaged roofs or sanitary facilities. From white rot infested stems are no longer to use as lumber.

A special form of white rot is the Weißlochfäule. It causes a selective degradation and occurs mainly in the nucleus of living coniferous and deciduous trees. Among others, the pine sponge ( Phellinus pini ) is a possible pathogen.

Evolution and pathogens

White rot as Stoffwechselart occurs exclusively on the case of fungi of the class Agaricomycetes. The basalste group is capable of this, the ear Fungal ( Auriculariales ). White rot occurs in both basal and derived groups in the class, but these clades are not necessarily next of kin. White rot is rather an original feature of the Agaricomycetes that is preserved by some side branches and was largely abandoned in favor of another of brown rot or Mykorrhizabildung. The first time she stepped in front of probably about 300 million years ago. She allowed the ancestors of today's Agaricomycetes to use lignin as a resource, and thus to take a previously unoccupied niche for itself in the claim.

New studies indicate a correlation between the formation of powerful near coal seams and the evolution of white rot. In the Carboniferous, there were no creatures that could degrade lignin. Only in the tertiary developed white-rot fungi, the lignin decomposed. In the subsequent period, coal was able to form only the absence of air.

Among the fungal groups engaged in white rot, include not only the ear lobes Fungal ( Auriculariales ) the bristle Scheiblingkirchen -like ( Hymenochaetales ), the splendor of beef Fungal ( Corticiales ), various branches of Stielporlingsartigen ( Polyporales ), the Täublingsartigen ( Russulales ) as well as some representatives of the mushroom -like ( Agaricales ).