Ultra low-dose radiation: Stress responses and impacts using rice model

Abstract

We have been investigating molecular changes in rice (Oryza sativa -crop/grass/genome model) leaves against various environmental stimuli. Our examination was extended to stress responses of rice to ultra low-dose ionizing radiation (IR) first using radioactively contaminated Chernobyl soil (CCS) from exclusion zone around Chernobyl reactor. For this purpose we established a two-week-old rice seedling in vitro model system. Rice leaves were irradiated 72 and 96 h above CCS (contained mainly Cs-137 as gamma-ray emitter), giving 5.34 microGy/day. First results revealed induction of stress-related marker genes and secondary metabolites in irradiated leaf segments over appropriate control. Secondly, employing the same in vitro model system, we replicated the first experiment using in-house fabricated Cs-137 sources with various gamma-ray intensities (2 microGy/day–100 microGy/day) and selected genes by RT-PCR. Results imply that ultra low-dose radiation elicits a defense/stress response in rice, a novel finding, suggesting rice plant as a simple and good model for investigating IR responses. Our colleague, Kimura S, will present details of experimental method at the poster session.
Reference. Rakwal, R. et al., 2009. Int. J. Mol. Sci. 10:1215-1225.