Bhattacharjee Payel, Lee YeonKyeong, Viejo Marcos, Gillard Gareth B, Sandve Simen Rød, Hvidsten Torgeir R, Salbu Brit, Brede Dag A, Olsen Jorunn E
Department of Plant Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432, Ås, Norway.
Centre of Environmental Radiation (CERAD), Norwegian University of Life Sciences, P.O. Box 5003, N-1432, Ås, Norway.
Planta. 2025 Sep 17;262(5):102. doi: 10.1007/s00425-025-04819-6.
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, 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, 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.
针叶树是对辐射最敏感的植物物种之一。电离辐射水平升高且处于亚致死状态会导致针叶树的顶端优势减弱，这表明对茎尖分生组织（SAMs）有负面影响。SAMs含有多能干细胞，能产生茎的所有细胞，从而实现生长和繁殖。然而，关于电离辐射对这类干细胞影响的知识却很匮乏，但这对于受污染生态系统中植物的风险评估和辐射防护很重要。在此，我们以挪威云杉体外培养的干细胞作为针叶树中γ辐射分子毒性的模型，评估了其对1 - 100 mGy/h的γ辐射144小时的敏感性。虽然γ辐射对细胞增殖和随后的胚胎形成没有明显影响，但在≥10 mGy/h时观察到剂量率依赖性DNA损伤，并且在所有剂量率下都出现了全面的细胞器损伤。发生了大量剂量率依赖性转录组变化，一系列与细胞分裂、DNA修复和蛋白质折叠相关的基因下调，但与应激相关的激素途径和几个与抗氧化剂相关的基因上调。这些基因的上调、至少一部分细胞的存活和持续增殖以及DNA修复和蛋白质折叠基因表达在辐照后的正常化以及体细胞胚胎形成表明干细胞能够从γ辐射诱导的应激中恢复。总体而言，尽管γ辐射后细胞出现异常，且转录组向应激管理途径发生巨大转变，但多能干细胞培养物仍能够保持其干性。
