Interactions between extraradical ectomycorrhizal mycelia, microbes associated with the mycelia and growth rate of Norway spruce (Picea abies) clones

Abstract

Research Summary• Despite their ecological relevance, field studies of the extraradical mycelia of ectomycorrhizal (ECM) fungi are rare. Here we examined in situ interactions between ECM mycelia and host vigour.• Ectomycorrhizal mycelia were harvested with in-growth mesh bags buried under Norway spruce ( Picea abies ) clones planted in 1994 in a randomized block design. Mycelial biomass was determined and fungal species were identified by denaturing gradient gel electrophoresis (DGGE) and sequencing of the internal transcribed spacer 1 (ITS1) region. Microbial community structure in the mycelium was investigated by phospholipid fatty acid (PLFA) profiling.• Compared to slow-growing spruce clones, fast-growing clones tended to support denser mycelia where the relative proportions of Atheliaceae fungi and PLFAs indicative of Gram-positive bacteria were higher. Ascomycetes and PLFAs representative of Gram-negative bacteria were more common with slow-growing clones. In general, the ECM mycelial community was similar to the ECM root-tip community.• Growth rate of the hosts, the ECM mycelial community and the microbes associated with the mycelium were related, suggesting multitrophic interactions between trees, fungi and bacteria.

Low diversity and high host preference of ectomycorrhizal fungi in Western Amazonia, a neotropical biodiversity hotspot

“…The presence of a single or a few host individuals on an island indicates no or very low fine-scale genetic diversity of suitable roots. Host genets may affect the community of EcM fungi by differential carbon availability (Korkama et al, 2007). Thus we speculate that genetic uniformity of hosts in vegetation islands may be related to the low species richness.…”

Effector MiSSP7 of the mutualistic fungus Laccaria bicolor stabilizes the Populus JAZ6 protein and represses jasmonic acid (JA) responsive genes

“…In particular, roots of most trees in temperate and boreal forests form a nutrient-acquiring symbiosis with mutualistic ectomycorrhizal (ECM) fungi (13). Trees that form a relationship with ECM fungi generally benefit from these relationships through an increase in growth rate and via elevated tolerance to biotic and abiotic stresses (13,14). Although ECM fungi are thought to have evolved from wood-and litter-decaying fungal ancestors, their lifestyle more closely reflects that of biotrophic pathogens (15)(16)(17).…”

“…Not all organisms attempting to colonize plant tissues, however, have adverse affects on plant health. In particular, roots of most trees in temperate and boreal forests form a nutrient-acquiring symbiosis with mutualistic ectomycorrhizal (ECM) fungi (13). Trees that form a relationship with ECM fungi generally benefit from these relationships through an increase in growth rate and via elevated tolerance to biotic and abiotic stresses (13,14).…”

Impact of an 8-Year-Old Transgenic Poplar Plantation on the Ectomycorrhizal Fungal Community

“…Fine roots colonized by EM fungi, also called EM root tips or ectomycorrhizae, display a fungal mantle from which extends the extraradical mycelium to prospect the soil for nutrient uptake. These two anatomical parts can be sampled for EM fungus molecular identification, but some studies have highlighted dissimilarities between the EM fungal diver-sity recorded in root tip sampling and that recorded in extraradical mycelium sampling (26,37,39).…”