The community of root fungi is associated with the growth rate of Norway spruce ( Picea abies )

Our study delved into the relationship between root‐associated fungi, gene expression and plant morphology in Norway spruce cuttings derived from both slow‐and fast‐growing trees. We found no clear link between the gene expression patterns of adventitious roots and the growth phenotype, suggesting no fundamental differences in the receptiveness to fungal symbionts between the phenotypes. Interestingly, saplings from slow‐growing parental trees exhibited a higher richness of ectomycorrhizal species and larger roots. Some ectomycorrhizal species, typically found on mature spruces, were more prevalent on saplings from slow‐growing spruces. The ericoid mycorrhizal fungus, Hyaloscypha hepaticola, showed a stronger association with saplings from fast‐growing spruces. Moreover, saplings from slow‐growing spruces had a greater number of Ascomycete taxa and free‐living saprotrophic fungi. Aboveground sapling stems displayed some phenotypic variation; saplings from fast‐growing phenotypes had longer branches but fewer whorls in their stems compared to those from the slow‐growing group. In conclusion, the observed root‐associated fungi and phenotypic characteristics in young Norway spruces may play a role in their long‐term growth rate. This suggests that the early interactions between spruces and fungi could potentially influence their growth trajectory

Activation of defence pathways in Scots pine bark after feeding by pine weevil (Hylobius abietis)

Background: During their lifetime, conifer trees are exposed to numerous herbivorous insects. To protect themselves against pests, trees have developed a broad repertoire of protective mechanisms. Many of the plant's defence reactions are activated upon an insect attack, and the underlying regulatory mechanisms are not entirely understood yet, in particular in conifer trees. Here, we present the results of our studies on the transcriptional response and the volatile compounds production of Scots pine (Pinus sylvestris) upon the large pine weevil (Hylobius abietis) feeding. Results: Transcriptional response of Scots pine to the weevil attack was investigated using a novel customised 36.4 K Pinus taeda microarray. The weevil feeding caused large-scale changes in the pine transcriptome. In total, 774 genes were significantly up-regulated more than 4-fold (p = 0.05), whereas 64 genes were significantly down-regulated more than 4-fold. Among the up-regulated genes, we could identify genes involved in signal perception, signalling pathways, transcriptional regulation, plant hormone homeostasis, secondary metabolism and defence responses. The weevil feeding on stem bark of pine significantly increased the total emission of volatile organic compounds from the undamaged stem bark area. The emission levels of monoterpenes and sesquiterpenes were also increased. Interestingly, we could not observe any correlation between the increased production of the terpenoid compounds and expression levels of the terpene synthase-encoding genes. Conclusions: The obtained data provide an important insight into the transcriptional response of conifer trees to insect herbivory and illustrate the massive changes in the host transcriptome upon insect attacks. Moreover, many of the induced pathways are common between conifers and angiosperms. The presented results are the first ones obtained by the use of a microarray platform with an extended coverage of pine transcriptome (36.4 K cDNA elements). The platform will further facilitate the identification of resistance markers with the direct relevance for conifer tree breeding.Peer reviewe

Cadophora margaritata sp. nov. and other fungi associated with the longhorn beetles Anoplophora glabripennis and Saperda carcharias in Finland

Symbiosis with microbes is crucial for survival and development of wood-inhabiting longhorn beetles (Coleoptera: Cerambycidae). Thus, knowledge of the endemic fungal associates of insects would facilitate risk assessment in cases where a new invasive pest occupies the same ecological niche. However, the diversity of fungi associated with insects remains poorly understood. The aim of this study was to investigate fungi associated with the native large poplar longhorn beetle (Saperda carcharias) and the recently introduced Asian longhorn beetle (Anoplophora glabripennis) infesting hardwood trees in Finland. We studied the cultivable fungal associates obtained from Populus tremula colonised by S. carcharias, and Betula pendula and Salix caprea infested by A. glabripennis, and compared these to the samples collected from intact wood material. This study detected a number of plant pathogenic and saprotrophic fungi, and species with known potential for enzymatic degradation of wood components. Phylogenetic analyses of the most commonly encountered fungi isolated from the longhorn beetles revealed an association with fungi residing in the Cadophora-Mollisia species complex. A commonly encountered fungus was Cadophora spadicis, a recently described fungus associated with wood-decay. In addition, a novel species of Cadophora, for which the name Cadophora margaritata sp. nov. is provided, was isolated from the colonised wood.Peer reviewe

Analysis of the Phlebiopsis gigantea Genome, Transcriptome and Secretome Provides Insight into Its Pioneer Colonization Strategies of Wood

Peer reviewe

Genome sequencing and population genomic analyses provide insights into the adaptive landscape of silver birch

Abstract Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B. pendula individual. Gene duplicates from the paleohexaploid event were enriched for transcriptional regulation, whereas tandem duplicates were overrepresented by environmental responses. Population resequencing of 80 individuals showed effective population size crashes at major points of climatic upheaval. Selective sweeps were enriched among polyploid duplicates encoding key developmental and physiological triggering functions, suggesting that local adaptation has tuned the timing of and cross-talk between fundamental plant processes. Variation around the tightly-linked light response genes PHYC and FRS10 correlated with latitude and longitude and temperature, and with precipitation for PHYC. Similar associations characterized the growth-promoting cytokinin response regulator ARR1, and the wood development genes KAK and MED5A