RT Journal Article T1 Gamma radiation‑induced molecular toxicity and effects on pluripotent stem cells of the radiosensitive conifer Norway spruce (Picea abies) A1 Bhattacharjee, Payel A1 Lee, YeonKyeong A1 Viejo Somoano, Marcos A1 Gillard, Bareth B. A1 Sandve, Simen Rod A1 Hvidsten, Torgeir R. A1 Salbu, Brit A1 Brede, Dag A. A1 Olsen, Jorunn E. K1 DNA damage K1 Gene expression K1 Ionising radiation K1 Organelle damage K1 Somatic embryogenesis K1 Transcriptome AB Conifers are among the most radiosensitive plant species. Elevated, sublethal levels of ionising radiation result in reduced apical dominance in conifers, indicating a negative effect on shoot apical meristems (SAMs). The SAMs, harbouring the pluripotent stem cells, generate all the cells of the shoot, enabling growth and reproduction. However, knowledge on the effects of ionising radiation on such stem cells is scarce, but important for risk assessment and radioprotection of plants in contaminated ecosystems. Here, we assessed the sensitivity of in vitro-grown stem cells of Norway spruce to 144 h of gamma irradiation at 1–100 mGy h−1, using such cells as a model for molecular toxicity of gamma radiation in conifers. Although there were no visible effects of the gamma irradiation on cell proliferation and subsequent embryo formation, dose rate-dependent DNA damage was observed at ≥ 10 mGy h−1, and comprehensive organelle damage at all dose rates. Massive dose rate-dependent transcriptome changes occurred, with downregulation of a range of genes related to cell division, DNA repair and protein folding but upregulation of stress-related hormonal pathways and several antioxidant-related genes. The upregulation of such genes, survival and continued proliferation of at least a subset of cells and the post-irradiation normalisation of expression of DNA repair and protein-folding genes together with somatic embryo formation suggest that stem cells are able to recover from gamma-irradiation-induced stress. Collectively, regardless of cellular abnormalities after gamma irradiation, and huge transcriptomic shifts towards stress management pathways, the pluripotent stem cell cultures were able to retain their stemness PB Springer Nature YR 2025 FD 2025-09-17 LK https://hdl.handle.net/10347/43441 UL https://hdl.handle.net/10347/43441 LA eng NO Bhattacharjee, P., Lee, Y., Viejo, M. et al. Gamma radiation-induced molecular toxicity and effects on pluripotent stem cells of the radiosensitive conifer Norway spruce (Picea abies). Planta 262, 102 (2025). https://doi.org/10.1007/s00425-025-04819-6 NO Research Council of Norway through its Centre of Excellence funding scheme (Grant 223268/F50) and from the Norwegian University of Life Sciences DS Minerva RD 24 abr 2026