Abstract
Plants in natural ecosystems are exposed to a combination of UV radiation, ionizing radiation (IR) and other abiotic factors. These factors change with the altitude. We investigated DNA alterations of some wild plants of different plant families in natural ecosystems at three altitudes in Rila Mountain, Bulgaria (1500, 1782, and 2925 m above sea level (a.s.l.) exposed to UV radiation, IR and other abiotic stresses, to assess the tolerance of plant species to the changing environmental conditions in three successive growth seasons. For this purpose, physicochemical, cytogenetic, and molecular methods were applied. DNA damage was assessed by micronucleus test and molecular method comet assay adapted and applied by us to wild plant species from Onagraceae, Rosaceae, Boraginaceae, Saxifragaceae, Orobanchaceae, Asteraceae and Poaceae families, growing at three different altitudes. Variability in the DNA sensitivity and the level of tolerance was observed among the plant species in response to combined abiotic factors assessed by induced DNA damage and gross beta activity. The studied representatives of Poaceae were less susceptible than the other studied species at all three altitudes and showed close level of DNA injuries to that of unaffected control plant grown in laboratory conditions. The lower levels of DNA damage of these wild plant species corresponded to their lower ability to accumulate radionuclides. There was a particularly pronounced low level of DNA injuries in the plant species at the highest altitude. The level of DNA damage showed correlation with the values of some abiotic environmental factors. The results would contribute to the elucidation of the extent of adaptation of plant species to the continuously changing environment and would be useful in selecting sensitive herbaceous monitor species for environmental impact assessment at mountain and alpine sites.
Highlights
As a result of climate change, along with growing anthropogenic pressure, plants in the natural ecosystems are forced to survive in extreme environmental conditions, with rapid changes in UV radiation, ionizing radiation (IR), temperature, humidity, precipitation, etc
We examined the effect of UV radiation, IR, temperature, humidity on DNA of wild plants growing at different altitudes in Rila Mountain as well as the extent of their adaptation for only one growing season [56]
The information obtained about the average daily values both for UV-A and UV-B at all three experimental sites showed that the values of these parameters for the growing season of 2017 were close to that of growing season 2019 at all three altitudes, as in 2019 these average daily values were slightly lower
Summary
As a result of climate change, along with growing anthropogenic pressure, plants in the natural ecosystems are forced to survive in extreme environmental conditions, with rapid changes in UV radiation, ionizing radiation (IR), temperature, humidity, precipitation, etc. Gudkov et al [1] commented that plants show modified responses under the combined effect of radiation and other abiotic stress factors. Many of the most important, yet less predictable consequences will be indirect effects of elevated UV-B rays acting through changes in the chemical composition and form of plants and through changes in the abiotic environment [2]. DNA is the main carrier of hereditary information in cells, which can undergo damage as a result of various environmental stress factors. PAR is defined as the electromagnetic radiation in the range of the light spectrum that phototrophic organisms mainly use in photosynthesis
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