Phylogenetic relationships, pathogenic traits, and wood-destroying properties of Porodaedalea niemelaei M. Fischer isolated in the northern forest limit of Larix gmelinii open woodlands in the permafrost area
Igor N. Pavlov, Yuliya A. Litovka, Tatyana V. Ryazanova, Nelli A. Chuprova, Ekaterina A. Litvinova, Yuliya A. Putintseva, Konstantin V. Krutovsky
Abstract
The phytopathogenic and wood destroying traits were studied in a basidiomycete fungus, Porodaedalea niemelaei M. Fischer, widespread in Siberian permafrost woodlands of Gmelinii larch, Larix gmelinii (Rupr.) Rupr. Numerous stands of dying out and fallen larch trees with white-rot („corrosion rot“) were found in the study area. Butt rot incidence varied from 63 to 100 % depending on the stand age and raised up to 0.5-1.5 m above root collar on average or up to 9 m maximum. Root rot was also widespread, including larch undergrowth. The biodiversity of xylotrophic fungi was low, with a pronounced dominance of P. niemelaei. The main factors of dying out of L. gmelinii were infection by P. niemelaei promoted by mechanical damage of roots by reindeers during migration and climate anomalies. The cultures isolated from the fruiting bodies were identified as Porodaedalea niemelaei M. Fischer based on the combination of morphological, culture and molecular genetic methods. Under laboratory conditions, the strains were characterized as psychrotolerant (temperature limit from 6 to 22 °C) and prefered cultural media based on natural ingredients and plant substrates. The most active biodegradation occured on the larch wood substrates causing up to 50 % of the biomass loss accompanied by active decomposing of the lignocellulosic complex and increasing the amount of water-soluble substances. The phylogenetic analysis demonstrated that P. niemelaei is clearly different from other well-studied Porodaedalea species, such as P. chrysoloma, P. pini, and P. cancriformans, and is very close to the group of unclassified fungi isolated in Norway and Finland. The phylogenetic analysis included 43 isolates and was based on four genetic markers - ITS, nLSU, rpb2, and tef1, commonly used in fungi phylogenetics. The sequences of all markers were verified in the recently completely sequenced genome of P. niemelaei representing the isolate used in this study (http://genome.jgi.doe.gov/PornieStandDraft_FD/PornieStandDraft_FD.info.html).