Project description:Conifer-specific responses to elicitation with the chemical elicitor chitosan have been investigated using a transcriptome analysis in Norway spruce using a cell suspension culture system that has been previously described (Phillips, Walter et al. 2007). This study has demonstrated that the early events following chitosan elicitation include calcium mediated signaling and an oxidative response that have not previously been described in intact trees. Keywords: stress response
Project description:Photosystem II (PSII) complexes are organized into large supercomplexes with variable amounts of light-harvesting proteins (Lhcb). A typical PSII supercomplex in plants is formed by four trimers of Lhcb proteins (LHCII trimers), which are bound to the PSII core dimer via monomeric antenna proteins. However, the architecture of PSII supercomplexes in Norway spruce (Picea abies (L.) Karst.) is different, most likely due to a lack of two Lhcb proteins, Lhcb6 and Lhcb3. Interestingly, the spruce PSII supercomplex shares similar structural features with its counterpart in the green alga Chlamydomonas reinhardtii (Kouřil et al.: New Phytol. 210, 808-814, 2016). Here we present a single-particle electron microscopy study of isolated PSII supercomplexes from Norway spruce that revealed binding of a variable amount of LHCII trimers to the PSII core dimer at positions that have never been observed in any other plant species so far. The largest spruce PSII supercomplex, which was found to bind 8 LHCII trimers, is even larger than the current largest known PSII supercomplex from Chlamydomonas reinhardtii. We have also shown that the spruce PSII supercomplexes can form various types of PSII megacomplexes, which were also identified in intact grana membranes. Some of these large PSII supercomplexes and megacomplexes were identified also in Pinus sylvestris, another representative of Pinaceae family. The structural variability and complexity of LHCII organization in Pinaceae seems to be related to the absence of Lhcb6 and Lhcb3 in this family and may be beneficial for the optimization of light-harvesting under varying environmental conditions.
Project description:We investigated root associated fungi in young Norway spruce (Picea abies) cuttings rooted from slow- and fast-growing trees showing variable growth rate in long-term field experiments and compared their roots’ gene expression patterns five and 18 months after adventitious root initiation. Gene expression patterns of adventitious roots could not be systematically linked with the growth phenotype at the initiation of root formation, and thus fundamental differences in the receptiveness of fungal symbionts could not be assumed.
Project description:The widespread use of plant grafting has enabled different plants to join and combine their best properties to improve stress tolerance, growth and yields. Grafting is commonly performed between closely related eudicots or gymnosperms where mechanisms permit tissue fusion yet limit success as plants become unrelated. To investigate these aspects, we developed a micrografting method using young conifer tree seedlings that enabled divergent conifer members to successfully graft. Conifer grafts showed rapid connection of phloem and xylem at the junction, while a genome-wide transcriptome analysis of the Picea abies (Norway spruce) healing junction revealed differential expression of thousands of genes including those related to auxin response and cell wall biogenesis. We compared these genes to those induced during Arabidopsis thaliana graft healing and found a common activation of cambium, cell division, phloem and xylem-related genes. A gene regulatory network analysis revealed that PHYTOCHROME A SIGNAL TRANSDUCTION 1 (PAT1) acted as a central hub during Picea grafting and was also induced during Arabidopsis grafting. Arabidopsis mutants lacking PATs failed to attach tissues or successfully graft, while complementing Arabidopsis PAT mutants with the Picea abies PAT1 homolog could rescue tissue attachment and enhance callus formation. Together, our data demonstrate a competency for young tissues to graft to distantly related species and identifies the PAT gene family as conserved regulators of graft healing and tissue regeneration in eudicots and gymnosperms.
Project description:In order to test Norway spruce radiosensitivity to gamma radiation, 6 days old seedlings were exposed for 48 h to 60-Co source at dose rates 1, 10, 40 or 100 mGy/h.