All living organisms are daily exposed to ionizing radiation coming from natural sources. However, due to anthropogenic activities exposure to radionuclides and radiation can be locally increased. For example the nuclear accident of Chernobyl in 1986 has led to a vast area contaminated with different radionuclides leading to increased radiation exposure of the ecosystem. A comparison between data coming from Chernobyl with those from lab experiments learned us that species were about eight fold more sensitive under field conditions. This raised concerns if existing risk assessments assays based on lab data were sufficient to estimate when the environment is protected from radiation.
To date it is still questionable whether organisms are able to adapt to chronic enhanced radiation levels or that damage induced by previous exposures accumulates. Moreover as there is this discrepancy between lab and field data, the results found in the lab need confirmation in field conditions. For plants, being sessile organisms not able to move away from enhanced levels of radiation, this is of particular importance. From our own lab experiments on different plant species we were able to show differences in the radiation response, for example on the induction of antioxidative and DNA repair mechanisms, depending on whether the plants were exposed for one or multiple generations. These results indicate that adaptive responses might play a role but the underpinning mechanisms are far from understood. Furthermore it is not known whether these responses also occur in the field nor how differences seen in individual plants link to a response at population level.
The main objective of this project is thus to study possible cellular and molecular (genetic/epigenetic) changes underpinning the adaptive responses of plants exposed to low doses of gamma radiation in both lab and field conditions. For field conditions we will use plants harvested alongside a gradient of contamination in the Chernobyl exclusion zone. This project will provide an answer to the following research questions: (i) Do previous radiation exposures render plants more resistant/susceptible towards additional new exposures in both lab and field conditions? (ii) Are molecular (epi)genetic markers present that mechanistically explain the observed adaptive responses? (iii) Does exposure to chronic low dose radiation lead to enhanced genetic variation and population dynamics? This research will lead to an increased mechanistic understanding of adaptation of plants to low-dose radiation. The data will help in estimating the impact of radiation on the environment.