Int. J. Mol. Sci. 2009, 10, 1215-1225; doi:10.3390/ijms10031215
International Journal of
Molecular Sciences
ISSN 1422-0067
www.mdpi.com/journal/ijms
Article
Ultra Low-Dose Radiation: Stress Responses and Impacts Using
Rice as a Grass Model
Received: 5 February 2009; in revised form: 11 March 2009 / Accepted: 13 March 2009 /
Published: 16 March 2009
Abstract: We report molecular changes in leaves of rice plants (Oryza sativa L. -
reference crop plant and grass model) exposed to ultra low-dose ionizing radiation, first
using contaminated soil from the exclusion zone around Chernobyl reactor site. Results
revealed induction of stress-related marker genes (Northern blot) and secondary
metabolites (LC-MS/MS) in irradiated leaf segments over appropriate control. Second, employing the same in vitro model system, we replicated results of the first experiment
using in-house fabricated sources of ultra low-dose gamma (g) rays and selected marker genes by RT-PCR. Results suggest the usefulness of the rice model in studying ultra lowdose radiation responses.
Keywords: Contaminated soil; g-ray; Marker genes; Oryza sativa; Phytoalexins.
[snip]
With this background, the radioactively contaminated soil should provide us with a good source
material for studying the effects of ionizing radiation (IR) on living organisms. Indeed, a single study
in two genetically identical wheat populations
revealed a remarkably strong induction of germline
mutation upon chronic exposure to low-dose IR (0.3 Gy over a period of 10 months) from the
Chernobyl accident [2]. Various physiological factors for the observed increased frequency of
heterozygous structural variants in the offspring derived from exposed plants were considered before
reaching to a conclusion that heterozygous variation was probably due to a radiation-induced increases
in microsatellite mutation in the exposed plants.
The results itself surprised Kovalchuk and coworkers,
and we quote them ?
theoretically, this low-level exposure should not cause such a large
increase in the mutation rate, suggesting that chronic exposure to IR has effects as yet unknown [2].
This one report highlighted the effect of low doses of IR in causing plant stress response. Therefore,
the use of plants to study low- or ultra low-dose IR becomes a reality, and which is communicated in
this report.
The plant model used was rice (Oryza sativa L.) ? a grass plant
? 2009 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.
This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
