Department of Plant Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway.
Centre of Environmental Radioactivity (CERAD), Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway.
Planta. 2019 Nov;250(5):1567-1590. doi: 10.1007/s00425-019-03250-y. Epub 2019 Aug 1.
Persistent DNA damage in gamma-exposed Norway spruce, Scots pine and Arabidopsis thaliana, but persistent adverse effects at the organismal and cellular level in the conifers only. Gamma radiation emitted from natural and anthropogenic sources may have strong negative impact on plants, especially at high dose rates. Although previous studies implied different sensitivity among species, information from comparative studies under standardized conditions is scarce. In this study, sensitivity to gamma radiation was compared in young seedlings of the conifers Scots pine and Norway spruce and the herbaceous Arabidopsis thaliana by exposure to Co gamma dose rates of 1-540 mGy h for 144 h, as well as 360 h for A. thaliana. Consistent with slightly less prominent shoot apical meristem, in the conifers growth was significantly inhibited with increasing dose rate ≥ 40 mGy h. Post-irradiation, the conifers showed dose-rate-dependent inhibition of needle and root development consistent with increasingly disorganized apical meristems with increasing dose rate, visible damage and mortality after exposure to ≥ 40 mGy h. Regardless of gamma duration, A. thaliana showed no visible or histological damage or mortality, only delayed lateral root development after ≥ 100 mGy h and slightly, but transiently delayed post-irradiation reproductive development after ≥ 400 mGy h. In all species dose-rate-dependent DNA damage occurred following ≥ 1-10 mGy h and was still at a similar level at day 44 post-irradiation. In conclusion, the persistent DNA damage (possible genomic instability) following gamma exposure in all species may suggest that DNA repair is not necessarily mobilized more extensively in A. thaliana than in Norway spruce and Scots pine, and the far higher sensitivity at the organismal and cellular level in the conifers indicates lower tolerance to DNA damage than in A. thaliana.
在γ射线暴露下，挪威云杉、欧洲赤松和拟南芥会出现持续的 DNA 损伤，但只有针叶树在机体和细胞水平上会出现持续的不良反应。来自天然和人为辐射源的γ射线可能会对植物产生强烈的负面影响，尤其是在高剂量率下。尽管之前的研究表明不同物种之间存在不同的敏感性，但在标准化条件下进行比较研究的信息仍然很少。在这项研究中，通过将针叶树挪威云杉和欧洲赤松以及草本拟南芥的幼苗暴露在 Coγ剂量率为 1-540 mGy h 的条件下 144 h，以及 360 h 用于拟南芥，比较了它们对γ辐射的敏感性。与略微不明显的茎尖分生组织一致，随着剂量率的增加（≥40 mGy h），针叶树的生长受到显著抑制。辐照后，随着剂量率的增加，针叶树的针和根发育呈剂量依赖性抑制，与剂量率增加时越来越紊乱的顶端分生组织一致，在暴露于≥40 mGy h 后可见损伤和死亡率。无论γ射线持续时间如何，拟南芥都没有可见或组织学损伤或死亡率，仅在暴露于≥100 mGy h 后出现侧根发育延迟，以及在暴露于≥400 mGy h 后出现轻微但短暂的生殖发育延迟。在所有物种中，在暴露于≥1-10 mGy h 后，都会出现剂量依赖性的 DNA 损伤，并且在辐照后第 44 天仍处于相似水平。总之，所有物种在γ射线暴露后出现的持续 DNA 损伤（可能是基因组不稳定性）可能表明，在拟南芥中，DNA 修复不一定比在挪威云杉和欧洲赤松中更广泛地被调动，而在机体和细胞水平上的敏感度要高得多在针叶树中表明对 DNA 损伤的耐受性低于拟南芥。
