Poster: Ecophysiology

Abs # 16: Molecular aspects of plant adaptation to chronic radiation exposure

Presenter:	Kovalchuk, Olga , olga.kovalchuk@uleth.ca
Authors	Kovalchuk, Olga  (A)   Pogribny, Igor  (B)   Titov, Viktor  (A)   Arkhipov, Andrey  (C)   Kovalchuk, Igor  (A)
Affiliations:	(A): University of Lethbridge, Canada (B): National Centre for Toxicological Research, USA (C): Chernobyl Centre, Chernobyl, Ukraine

We study the fundamental biological processes that govern plant responses and adaptations radiation exposure and radiation sensitivity, the molecular players and communication involved in such responses. We use molecular, genetic and physiological approaches with a strong emphasis on the analysis of global genome expression as well as epigenetic changes to understand the molecular mechanisms of plant adaptation to radiation. We applied DNA microarray technology to identify radiation-regulated genes in the model organism A. thaliana and studied their expression under various conditions of acute and chronic irradiation. This approach led to identification of several radiation-responsive genes. We also analyzed genetic changes in several generations of Arabidopsis grown in Chernobyl. We evaluated changes in plant genome stability by looking at homologous recombination (HR) and germline mutation in several generations of plants. Detailed analysis of several generations of exposed plants revealed that the rates of HR, somatic and germline mutation in plants were strongly elevated. In parallel we studied radiation-induced epigenetic changes. Among those we evaluated genome methylation status of exposed plants and the relationship between genome methylation status and plant adaptation to radiation. We have found that genomic DNA of exposed Arabidopsis plants was considerably hypermethylated. Such hypermethylation may be viewed as a defense strategy of a plant to prevent genome instability and reshuffling of the hereditary material, and allowing survival in extreme environment. Based on the aforementioned data, the possible models of plant adaptation to chronic irradiation will be presented.