A comprehensive study of the biological effects of chronic radiation exposure (8 μGy/h) in populations of white clover (Trifolium repens L.) from the Chernobyl exclusion zone was carried out. White ...clover is one of the most important pasture legumes, having many agricultural applications. Studies at two reference and three radioactively contaminated plots showed no stable morphological effects in white clover at this level of radiation exposure. Increased activities of catalase and peroxidases were found in some impacted plots. Auxin concentration was enhanced in the radioactively contaminated plots. Genes involved in the maintenance of water homeostasis and photosynthetic processes (TIP1 and CAB1) were upregulated at radioactively contaminated plots.
•Dose rate up to 8 μGy/h is insufficient to induce stable morphological changes.•Antioxidant responses could be stimulated by chronic irradiation.•The auxin concentrations increase at the most radioactive plots.•Aquaporins and LHCII components can respond to radiation.
At low intensity, certain stress conditions may have a positive effect on growth and development of plants (eustress). Growth stimulation of barley plants after gamma irradiation of seeds in low ...doses was observed as an increase in root and shoot lengths. Hydrogen peroxide concentrations in shoots of irradiated plants were significantly higher than in control, while the opposite effect was observed in the roots. To elucidate the molecular basis of growth stimulation after gamma irradiation of barley seeds, we performed the transcriptomic analysis of barley embryos at different stages of seed germination. The transcriptomic data were correlated with morphological parameters and the hydrogen peroxide levels in irradiated and control plants. These data indicate that the growth stimulation by low‐dose irradiation involves the transcriptional control of genes related to phytohormones, antioxidant system, late embryogenesis abundant proteins and cell wall components, with possible involvement of jasmonate and ABA signalling. Gamma irradiation of seeds at dose 100 Gy caused significant growth inhibition and promoted expression changes in transcripts related to cell cycle arrest, DNA damage repair and antioxidant system.
Gamma (γ)-irradiation of plants at low doses can provoke a broad range of growth-stimulating effects. In order to reveal universal target genes that are involved in molecular pathways of radiation ...hormesis establishment, we studied nine barley cultivars for their tolerance to γ-irradiation of seeds. Four morphological traits were assessed in barley seedlings after γ-irradiation of seeds at 20 Gy. Nine cultivars were sorted according to the sensitivity to irradiation as γ-stimulated, “no morphological effect”, or γ-inhibited. Gene expression of 17 candidate genes was evaluated for the 7 most contrasting cultivars. Changes in expression of barley homologues of PM19L and CML31 were suggested as possible determinants of radiation hormesis effect. The possible role of jasmonate signaling in roots in radiation growth stimulations was revealed. Morphological analysis and gene expression study showed that the genetic background of a cultivar plays an important role in eustress responses to low-dose γ-irradiation of seeds.
Five herbaceous plant species (Aquilegia vulgaris L., Capsella bursa-pastoris L., Dactylis glomerata L., Taraxacum officinale Wigg., and Trifolium repens L.) were sampled at twelve plots in the ...radioactively contaminated Chernobyl exclusion zone. These plots comprise dose rates from 0.27 to 12.5 μGy/h. The sensitivity of each plant species to chronic multigenerational radiation exposure was estimated using a broad range of parameters, including transcriptional, biochemical, physiological, morphological, and reproductive end-points. We suggest that chronic radiation exposure may influence the state of antioxidant system of chronically irradiated plants in a species-specific way, possibly leading to changes in photosynthetic capacity. ATP and ABA contents were not influenced by chronic irradiation at the plots. For most of the species studied, chlorophyll a fluorescence measurements may be a more appropriate way to assess the stress response to chronic irradiation, while biochemical parameters had significantly higher natural heterogeneity. High-throughput sequencing of the transcriptome of C. bursa-pastoris leaves from radioactively contaminated plots revealed significant stress response to chronic irradiation and supported a predicted important role of histones and chaperons in adaptation to chronic radiation exposure in field conditions. Overall, the results suggest that a prediction of herbaceous species sensitivity to chronic radiation might be initially derived from data on sensitivity to acute radiation exposure.
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•Radiation influenced transcriptional, biochemical, and physiological end-points.•Antioxidant responses could be stimulated or suppressed by chronic irradiation.•Photosynthesis is important for plant stress response to chronic exposure.•RNA-Seq of C. bursa-pastoris revealed stress response profile to chronic irradiation.•Plant sensitivity to acute and chronic irradiation is often similar.
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