Project description:Coping of evergreen conifers of boreal forests with freezing temperatures on bright winter days puts the photosynthetic machinery in great risk of oxidative damage. To survive harsh winter conditions, conifers have evolved a unique but poorly characterised photoprotection mechanism, a sustained form of non-photochemical quenching (sustained NPQ). Here we focused on functional properties and underlying molecular mechanisms related to the development of sustained NPQ in Norway spruce (Picea abies). Data was collected during four consecutive years (2016-19) from trees growing in sun and shade habitats. When day temperatures dropped below -4°C, specific N-terminally triply phosphorylated LHCB1 isoform (3p-LHCII) and phosphorylated PSBS (p-PSBS) were detected in the thylakoid membrane. Development of sustained NPQ coincided with the highest level of 3p-LHCII and p-PSBS, occurring after prolonged combination of bright winter days and temperature close to -10°C. Artificial induction of both the sustained NPQ and recovery from naturally induced sustained NPQ provided information on differential dynamics and light-dependence of 3p-LHCII and p-PSBS accumulation and dephosphorylation as essential prerequisites of sustained NPQ. Data obtained collectively suggest three novel components related to sustained NPQ in spruce. (i) Freezing temperatures induce 3p-LHCII accumulation independently of light, which is suggested to initiate de-stacking of appressed thylakoid membranes due to increased electrostatic repulsion of adjacent membranes. (ii) p-PSBS accumulation is both light- and temperature-dependent and closely linked to the initiation of sustained NPQ, which (iii) in concert with PSII photoinhibition is likely to trigger sustained NPQ in spruce.
Project description:The response mechanisms, recognition and specificity of conifer trees during interaction with pathogenic, saprotrophic or symbiotic ectomycorrhizal fungus were investigated. The roots of Pinus sylvestris were challenged for five days with either Heterobasidion annosum (a pathogenic root rot fungus which attacks Norway spruce, Scots pine and broad leaf trees); Laccaria bicolor (an obligate ectomycorrhizal symbiont); or Trichoderma aureoviride (an obligate saprotroph). The gene expression data from cDNA micro-arrays consisting of 2176 Pinus taeda genes were analysed using 2-interconnected mixed linear model statistical approach. The result of the pairwise comparisons of the different treatments against un-inoculated control led to identification of genes specifically differentially expressed in the pathogenic, saprotrophic and symbiotic interactions. The results were compared with similar data obtained for two other interaction stages: 1 and 15 days post inoculation. The result of this comprehensive expression profiling will hopefully shed more light on the mechanistic basis for recognition and response of conifer trees to pathogenic and non-pathogenic fungi. Keywords: stress response
Project description:The response mechanisms, recognition and specificity of conifer trees during interaction with pathogenic, saprotrophic or symbiotic ectomycorrhizal fungus were investigated. The roots of Pinus sylvestris were challenged for fifteen days with either Heterobasidion annosum (a pathogenic root rot fungus which attacks Norway spruce, Scots pine and broad leaf trees); Laccaria bicolor (an obligate ectomycorrhizal symbiont); or Trichoderma aureoviride (an obligate saprotroph). The gene expression data from cDNA micro-arrays consisting of 2176 Pinus taeda genes were analysed using 2-interconnected mixed linear model statistical approach. The result of the pairwise comparisons of the different treatments against un-inoculated control led to identification of genes specifically differentially expressed in the pathogenic, saprotrophic and symbiotic interactions. The results were compared with similar data obtained for two other interaction stages: 1 and 5 days post inoculation. The result of this comprehensive expression profiling will hopefully shed more light on the mechanistic basis for recognition and response of conifer trees to pathogenic and non-pathogenic fungi. Keywords: stress response
Project description:Many trees form ectomycorrhizal symbiosis with fungi. During symbiosis, the tree roots supply sugar to the fungi in exchange for nitrogen, and this process is critical for the nitrogen and carbon cycles in forest ecosystems. However, the extents to which ectomycorrhizal fungi can liberate nitrogen and modify the soil organic matter and the mechanisms by which they do so remain unclear since they have lost many enzymes for litter decomposition that were present in their free-living, saprotrophic ancestors. Using time-series spectroscopy and transcriptomics, we examined the ability of two ectomycorrhizal fungi from two independently evolved ectomycorrhizal lineages to mobilize soil organic nitrogen. Both species oxidized the organic matter and accessed the organic nitrogen. The expression of those events was controlled by the availability of glucose and inorganic nitrogen. Despite those similarities, the decomposition mechanisms, including the type of genes involved as well as the patterns of their expression, differed markedly between the two species. Our results suggest that in agreement with their diverse evolutionary origins, ectomycorrhizal fungi use different decomposition mechanisms to access organic nitrogen entrapped in soil organic matter. The timing and magnitude of the expression of the decomposition activity can be controlled by the below-ground nitrogen quality and the above-ground carbon supply.
2018-11-30 | GSE110485 | GEO
Project description:Nitrogen fertilisation differentially affects the symbiotic capacity of two co-occurring ectomycorrhizal species
Project description:We constructed four PARE libraries for the identification of miRNA target genes in Norway spruce. PARE libraries were constructed from four different tissues