The mutation mechanism of low-energy-ion has been under debates owing to their short-penetrating ability in biological tissues. Scientists from Ion Beam Bioengineering Lab, Institute of Plasma Physics (IPP), made important progress in this area with the funding supports from National Scientific Foundation of China and CAS Key Innovation Project.

A research group at IPP, established a new system using the homologous recombination (HR) in somatic cells and the expression of AtRAD54 gene as biological endpoints, which provides a quantitative evaluation of genetic changes at the DNA level. Their study demonstrates the existence of long-distance mutagenesis of ionizing radiation in plants, which sheds some new light on the plant mutagenesis of low-energy-ions. In this study, when the distal primary roots of Arabidopsis seedlings were radiated with 10Gy of alpha-particles, an increase of homologous recombination frequency and up-regulated expression of AtRAD54 gene were observed in the aerial plants, which were not exposed to ion beam radiation. The non-targeted aerial plants also showed an elevated level of DNA strand breaks. Both the increased ROS and the repressive effect of DMSO, a radical scavenger, on the HR and expression of AtRAD54 gene, suggest an implication of ROS in long-distance mutagenesis of ionizing radiation in plants. A manuscript about this study has been accepted by the journal of “Radiation Research”. 

The second study was on Formaldehyde (FA), an environmental genotoxical factor that has been widely used in making many commercial products such as carpeting, drapery and garments. The same genetic changes evaluating system used in the first study was used to evaluate the genotoxicty of FA. After the FA-exposure, a persistent increase in HRF and short-term up-regulation of AtRAD54 gene were observed in testing plants. This is the first time that transgenic plants for HR substrates were used in evaluating the genotoxicity of FA. The results will be published on “Mutation Research/Genetic Toxicology and Environmental Mutagenesis mutation”.