Ectomycorrhizal fungus supports endogenous rhythmic growth and corresponding resource allocation in oak during various below- and aboveground biotic interactions.

Endogenous rhythmic growth (ERG) is displayed by many tropical and some major temperate tree species and characterized by alternating root and shoot flushes (RF and SF). These flushes occur parallel to changes in biomass partitioning and in allocation of recently assimilated carbon and nitrogen. To address how biotic interactions interplay with ERG, we cross-compared the RF/SF shifts in oak microcuttings in the presence of pathogens, consumers and a mycorrhiza helper bacterium, without and with an ectomycorrhizal fungus (EMF), and present a synthesis of the observations.

Balance between geographic, soil, and host tree parameters to shape soil microbiomes associated to clonal oak varies across soil zones along a European North-South transect.

Tree root-associated microbiomes are shaped by geographic, soil physico-chemical, and host tree parameters. However, their respective impacts on microbiome variations in soils across larger spatial scales remain weakly studied. We out-planted saplings of oak clone DF159 (Quercus robur L.

Oak displays common local but specific distant gene regulation responses to different mycorrhizal fungi.

Background: Associations of tree roots with diverse symbiotic mycorrhizal fungi have distinct effects on whole plant functioning. An untested explanation might be that such effect variability is associated with distinct impacts of different fungi on gene expression in local and distant plant organs. Using a large scale transcriptome sequencing approach, we compared the impact of three ectomycorrhizal (EMF) and one orchid mycorrhizal fungi (OMF) on gene regulation in colonized roots (local), non-colonized roots (short distance) and leaves (long distance) of the Quercus robur clone DF159 with reference to the recently published oak genome.

Tree Root Zone Microbiome: Exploring the Magnitude of Environmental Conditions and Host Tree Impact.

Tree roots attract their associated microbial partners from the local soil community. Accordingly, tree root-associated microbial communities are shaped by both the host tree and local environmental variables. To rationally compare the magnitude of environmental conditions and host tree impact, the "PhytOakmeter" project planted clonal oak saplings ( L.

Collembola interact with mycorrhizal fungi in modifying oak morphology, C and N incorporation and transcriptomics.

Soil detritivores such as Collembola impact plant growth, tissue nutrient concentration and gene expression. Using a model system with pedunculate oak () microcuttings that display a typical endogenous rhythmic growth with alternating shoot (SF) and root flushes (RF), we investigated the transcriptomic response of oak with and without mycorrhiza () to the presence of Collembola (), and linked it to changes in resource allocation by pulse labelling the plants with C and N. Collembola impacted Gene Ontology (GO) terms as well as plant morphology and elemental ratios with the effects varying markedly with developmental phases.

Tree Response to Herbivory Is Affected by Endogenous Rhythmic Growth and Attenuated by Cotreatment With a Mycorrhizal Fungus.

Herbivores and mycorrhizal fungi interactively influence growth, resource utilization, and plant defense responses. We studied these interactions in a tritrophic system comprising , the herbivore , and the ectomycorrhizal fungus under controlled laboratory conditions at the levels of gene expression and carbon and nitrogen (C/N) allocation. Taking advantage of the endogenous rhythmic growth displayed by oak, we thereby compared gene transcript abundances and resource shifts during shoot growth with those during the alternating root growth flushes.

The Dark Side of Animal Phenology.

Research exploring the timing of recurring biological events has shown that anthropogenic climate change dramatically alters the phenology of many plants and animals. However, we still lack studies on how climate change might alter the phenology of soil invertebrates as well as how this can subsequently affect ecosystem functions.

Growing Research Networks on Mycorrhizae for Mutual Benefits.

Research on mycorrhizal interactions has traditionally developed into separate disciplines addressing different organizational levels. This separation has led to an incomplete understanding of mycorrhizal functioning. Integration of mycorrhiza research at different scales is needed to understand the mechanisms underlying the context dependency of mycorrhizal associations, and to use mycorrhizae for solving environmental issues.

Transcriptome analysis in oak uncovers a strong impact of endogenous rhythmic growth on the interaction with plant-parasitic nematodes.

Background: Pedunculate oak (Quercus robur L.), an important forest tree in temperate ecosystems, displays an endogenous rhythmic growth pattern, characterized by alternating shoot and root growth flushes paralleled by oscillations in carbon allocation to below- and aboveground tissues. However, these common plant traits so far have largely been neglected as a determining factor for the outcome of plant biotic interactions.

Large scale transcriptome analysis reveals interplay between development of forest trees and a beneficial mycorrhiza helper bacterium.

Background: Pedunculate oak, Quercus robur is an abundant forest tree species that hosts a large and diverse community of beneficial ectomycorrhizal fungi (EMFs), whereby ectomycorrhiza (EM) formation is stimulated by mycorrhiza helper bacteria such as Streptomyces sp. AcH 505. Oaks typically grow rhythmically, with alternating root flushes (RFs) and shoot flushes (SFs).

The oak gene expression atlas: insights into Fagaceae genome evolution and the discovery of genes regulated during bud dormancy release.

Background: Many northern-hemisphere forests are dominated by oaks. These species extend over diverse environmental conditions and are thus interesting models for studies of plant adaptation and speciation. The genomic toolbox is an important asset for exploring the functional variation associated with natural selection.

Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists.

To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose.

Sweets for the foe - effects of nonstructural carbohydrates on the susceptibility of Quercus robur against Phytophthora quercina.

The root-rot pathogen Phytophthora quercina is a key determinant of oak decline in Europe. The susceptibility of pedunculate oak (Quercus robur) to this pathogen has been hypothesized to depend on the carbon availability in roots as an essential resource for defense. Microcuttings of Q.

Streptomyces-induced resistance against oak powdery mildew involves host plant responses in defense, photosynthesis, and secondary metabolism pathways.

Rhizobacteria are known to induce defense responses in plants without causing disease symptoms, resulting in increased resistance to plant pathogens. This study investigated how Streptomyces sp. strain AcH 505 suppressed oak powdery mildew infection in pedunculate oak, by analyzing RNA-Seq data from singly- and co-inoculated oaks.

Detection and quantification of a mycorrhization helper bacterium and a mycorrhizal fungus in plant-soil microcosms at different levels of complexity.

Background: Host plant roots, mycorrhizal mycelium and microbes are important and potentially interacting factors shaping the performance of mycorrhization helper bacteria (MHB). We investigated the impact of a soil microbial community on the interaction between the extraradical mycelium of the ectomycorrhizal fungus Piloderma croceum and the MHB Streptomyces sp. AcH 505 in both the presence and the absence of pedunculate oak microcuttings.

OakContigDF159.1, a reference library for studying differential gene expression in Quercus robur during controlled biotic interactions: use for quantitative transcriptomic profiling of oak roots in ectomycorrhizal symbiosis.

Oaks (Quercus spp.), which are major forest trees in the northern hemisphere, host many biotic interactions, but molecular investigation of these interactions is limited by fragmentary genome data. To date, only 75 oak expressed sequence tags (ESTs) have been characterized in ectomycorrhizal (EM) symbioses.

Cross talks at the morphogenetic, physiological and gene regulation levels between the mycobiont Piloderma croceum and oak microcuttings (Quercus robur) during formation of ectomycorrhizas.

Ectomycorrhiza, a symbiosis between soil fungi and the rootlets of major forest trees, is characterized by well defined anatomical traits but also encompasses a wide range of ecological and physiological situations. Functional studies of this symbiosis therefore address different kinds of systems. Here we review works done on an experimental model with micropropagated oak cuttings infected in a Petri dish system with the basidiomycote Piloderma croceum.

Transcriptional changes in two types of pre-mycorrhizal roots and in ectomycorrhizas of oak microcuttings inoculated with Piloderma croceum.

The formation of the ectomycorrhiza implies an alteration in gene expression of both the plant and fungal partners, a process which starts before the formation of any symbiotic interface. However, little is known on the regulation pattern occurring in different parts of the root system. Our experimental system consisting of a micropropagated oak with a hierarchical root system was shown to exhibit symbiosis functional traits prior to any mycorrhizal tissue differentiation after the inoculation with the basidiomycete Piloderma croceum.

Differential expression of two class III chitinases in two types of roots of Quercus robur during pre-mycorrhizal interactions with Piloderma croceum.

Expression of two plant chitinase genes, representing members of class III chitinases, was studied in Quercus robur roots during interactions in a pre-mycorrhizal stage with the ectomycorrhizal fungus Piloderma croceum. Chitinase gene expression was compared in lateral roots destined to form ectomycorrhiza, and in principal roots that are not directly involved in mycorrhizal interactions. The transcript level of the first chitinase (QrchitIII-1) was upregulated in lateral roots, whereas no significant differential expression was observed in principal roots.

Identification of premycorrhiza-related plant genes in the association between Quercus robur and Piloderma croceum.

•  An in vitro system with micropropagated oaks (Quercus robur) and the ectomycorrhizal fungus Piloderma croceum, which is characterized by a delayed mycorrhiza formation, was used to identify plant transcripts upregulated in the premycorrhizal phase. •  Complementary DNA (cDNA) populations of uninoculated roots and fungal mycelium were subtracted from a cDNA population of inoculated roots. Differential expression was confirmed by reverse Northern and 50 clones for different polypeptides were found to be up-regulated.

Manipulation of the onset of ectomycorrhiza formation by indole-3-acetic acid, activated charcoal or relative humidity in the association between oak microcuttings and Piloderma croceum: influence on plant development and photosynthesis.

A Petri dish system in which development of oak (Quercus robur L.) microcuttings is stimulated by the late stage ectomycorrhizal (EM) fungus Piloderma croceum J. Erikss.