Non-thermal plasma generated under atmospheric pressure produces a mixture of chemically reactive
molecules and has been developed for a number of biomedical applications. Recently, plasma jet has been
proposed as novel cancer therapies based on the observation that free radicals generated by plasma jet
induce mitochondria-mediated apoptotic cell death. We show here that air plasma jet induces DNA
double-strand breaks (DSBs) in yeast chromosomes leading to genomic instability and loss of viability,
which are alleviated by Rad51, the yeast homolog of Escherichia coli RecA recombinase, through DNA
damage repair by a homologous recombination (HR) process. Hypersensitivity of rad51 mutant to air
plasma was not restored by antioxidant treatment unlike sod1 mutant that was highly sensitive to
reactive oxygen species (ROS) challenge, suggesting that plasma jet induces DSB-mediated cell death
independent of ROS generation. These results may provide a new insight into the mechanism of air
plasma jet-induced cell death.