The increasing concern about ecological impacts of wood preservation chemicals has raised the interest in the natural durability of Scots pine (Pinus sylvestris L.) heartwood. Phenolic compounds—stilbenes—have been found to inhibit fungal growth, making heartwood more resistant to decay. There is a strong genetic component in the stilbene content of the heartwood in Scots pine, with a positive correlation between stilbene content in the heartwood of mother trees and their progenies. Vegetative propagation, i.e., somatic embryogenesis (SE) of Scots pine genotypes with high content of stilbenes could provide a way to produce more durable timber, assuming that there is no trade-off between SE propagation and capacity for high stilbene synthesis. To study this, we made SE initiations from parent genotypes with high and low content of stilbenes in their heartwood, using seed embryos from both open-pollinations and controlled crossings as explants. The success of SE was followed from initiation to embling acclimatization, together with measurements of stilbene content in the explants and the established SE lines. The results show that SE can be induced and emblings regenerated from trees with both high and low content of stilbene. Content of stilbenes was generally low in SE cultures and varied widely among the lines. Following the successful initiation, the later phases of SE propagation proceeded with no connection to the parent genotypes or the stilbene level of the ECs and had large variation among SE-lines.

Wood is a widely used indoor material, and thus it is important to consider wood performance in microbial cross contamination via surfaces. In this study, both untreated and surface- treated wood materials were studied by simulating airborne bacterial contamination and evaluating the number of bacterial colonies on the material surfaces. The materials studied were untreated pine heartwood and sapwood, spruce, silver birch, and glass as a reference. The intensity of UV-excited fluorescence was measured to find the most antibacterial Scots pine heartwood. The coatings used were varnish and wax for Scots pine sapwood. The surface roughness of all material types was compared, and it was found to be uniform. All untreated wood surfaces had less viable bacterial colonies at all time points compared to the glass reference, and the surface treated samples did not differ from the glass reference indicating that the antibacterial properties of wood were blocked by both varnish and wax. The fluorescence method was practical to use, but wider testing will be needed to validate it more thoroughly. The results indicate also that silver birch has similar antibacterial properties as pine and spruce and hence should be studied further.

Stilbenes are developmentally induced metabolites in Scots pine heartwood where they have important role in protecting wood from decaying fungi. The stilbene pathway is also stress inducible, and ultraviolet (UV)-C radiation was among the first discovered artificial stress activators of the pathway. Many conditions that activate the pathway are known, but the specific transcriptional regulators and the biosynthetic enzyme responsible for activating the stilbene precursor cinnamate in the pathway are unknown. Here we describe the first large-scale transcriptomic analysis of pine needles in response to UV-C exposure and treatment with translational inhibitor cycloheximide, both activating the transcription of stilbene pathway genes, to uncover the candidates for the transcriptional regulation of the pathway and the cinnamate activating CoA ligase. We show that the regulation of pine stilbene pathway has shared features with grapevine stilbene pathway. In both species, the stilbene pathway was transcriptionally activated after UV-C treatment, protein phosphatase inhibitors and plant hormones ethylene and jasmonate. The pine stilbene synthase promoter retains its inducibility when transformed in plants that normally do not synthesize stilbenes. Pine stilbene synthase promoter was able to activate the expression of a reporter gene in Arabidopsis in response to UV-C exposure and phosphatase inhibitors, but not as response to plant hormone treatment. This indicates that stilbene synthase gene regulation occurs both via ancient stress-response pathway(s) but also via species specific regulators. With transcriptomic approach we identified candidate enzymes for cinnamate acting CoA ligase and transcription factors regulating the pathway.