Pathogenicity of ophiostomatoid fungi on Picea abies in Slovenia

Abstract

Pathogenic fungi can survive and develop in living plants, often causing diseases in the host. Some theories speculate that pathogenic ophiostomatoid fungi provide benefits to its vectorsbark beetlesby overcoming the tree's defence mechanisms. This study reports the results of an experiment in south-eastern Europe in which mature and seedling Norway spruce trees were artificially inoculated with various ophiostomatoid fungi. The aim of the experiment was to determine the relative virulence of ophiostomatoid fungi by assessing the ability of the fungi to stimulate host tree defence mechanisms through inoculation experiments. Experiments were performed by inoculation of Picea abies in seedling and mature trees. The following fungi were used in low-density and seedling inoculations: Ophiostoma ainoae, O. brunneo-ciliatum, Grosmannia cucullata and an unidentified Leptographium sp., O. bicolor, O. fuscum, O. piceae, G. penicillata and G. piceiperda. Endoconidiophora polonica was used in mass and seedling inoculations. Various characteristics such as host vitality, blue stain, lesion and resin outflow were measured before and after the trees were felled. E. polonica caused blue stain, induced large lesions and killed some of the mature trees and seedlings, confirming earlier reports that it is a strong wound pathogen. Only E. polonica, Leptographium sp. and O. ainoae caused blue stains in the sapwood of inoculated seedlings. In low-density inoculations, G. piceiperda induced intense necrosis and had higher values for all the characteristics monitored. Some of the other ophiostomatoid fungi showed a moderate level of pathogenicity. Fungi with the capacity to stimulate a host defence mechanism could play a role in the establishment of bark beetle populations.

Effects of water availability on a forestry pathosystem: fungal strain-specific variation in disease severity

“…A necrotrophic pathogen of increasing concern to Norway spruce is Endoconidiophora polonica , which has been demonstrated capable of killing mature trees 11 – 13 . This fungus is commonly vectored by the Eurasian spruce bark beetle ( Ips typographus ); the most important pest of mature P. abies trees in Europe 14 .…”

“…Here we report on a large in vivo experiment, conducted in an open greenhouse in southern Finland, to evaluate the effects of water availability on E. polonica infected Norway spruce seedlings during an annual growing season. Seedlings have been previously demonstrated as an effective model for larger tree health in this pathosystem 12 , 13 . A total of 737 seedlings were randomized to high (W+) or low (W−) water availability treatment groups, and inoculated with one of three fungal strains (designated F3 - F5 25 ) or mock-inoculated.…”

Draft genome sequences for Ceratocystis fagacearum, C. harringtonii, Grosmannia penicillata, and Huntiella bhutanensis

“…It is vectored by various scolytine bark beetle species ( Coleoptera; Curculionidae; Scolytinae ) but most importantly, by the aggressive tree-killing bark beetle Ips typographus (Jacobs & Wingfield 2001, Linnakoski et al 2012). Inoculation studies have indicated that G. penicillata is not pathogenic to its hosts (Jankowiak et al 2009, Repe et al 2015). This is unlike Endoconidiophora polonica, as defined by de Beer et al .…”

“…This is unlike Endoconidiophora polonica, as defined by de Beer et al . (2014), that is a common associate of I. typographus and is able to kill trees in inoculation tests (Horntvedt et al 1983, Repe et al 2015). …”

Testing Projected Climate Change Conditions on the Endoconidiophora polonica / Norway spruce Pathosystem Shows Fungal Strain Specific Effects

“…Previous research has demonstrated that seedlings provide an effective model for larger tree health within this system (Krokene and Solheim, 1998; Repe et al, 2015). Due to the general inability of this tree species to adjust to environmental changes, we hypothesized that disease severity on seedlings would be greater under predicted future climate change scenarios than current ambient conditions.…”