Radiosensitivity of herbaceous plants to chronic radiation exposure: Field study in the Chernobyl exclusion zone

Abstract

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.