Pinus Sylvestris as a Reference Plant Species in Radiation Research: Transcriptomics of Trees from the Chernobyl Zone

Pinus species are highly suitable for monitoring anthropogenic pollutants, including air contaminants, heavy metals and radionuclides. Scots pine (Pinus sylvestris L.) is one of the most widely distributed conifers in the world, and is characterized by a high sensitivity to environmental pollutants and an increased ability to accumulate pollutants in tissues. Because of its large genome size, this species is extremely sensitive to ionizing radiation, thus considered by the International Commission on Radiological Protection as a reference plant for radiation protection of biota. Current approaches in functional genomics and bioinformatics allow studying the transcriptional profiles of P. sylvestris in radioactively contaminated areas, revealing adaptive responses at a previously unattainable level. In the Chernobyl exclusion zone, where natural populations are under low-dose chronic radiation stress, such responses include direct structural protection of DNA integrity from radiation damage and modulation of reactive oxygen species production. Chronically irradiated pine populations have increased expression of genes encoding heat shock proteins and histones. However, no differential expression of genes related to DNA repair was revealed, while the transcriptional responses pointed to modulation of redox cellular homeostasis. These observations suggest that the response patterns to chronic low-dose and acute high-dose ionizing radiation exposure are partially different. Biomonitoring properties of P. sylvestris and a pipeline for assembling the transcriptome of this non-model species are also discussed.