Investigating the Induction of the Flash Effect By Ultra-High Dose Rate (UHDR) Electron Beams through Differential Gene Expression In a Plant Species
Abstract
Purpose
To investigate whether ultra-high dose rate (UHDR) electron beams induce a FLASH effect, quantified through differential gene expression in the plant species Arabidopsis thaliana.
Methods
Six Arabidopsis thaliana seeds were planted inside twelve Petri dishes and grown to a two-week maturity. This species was chosen for its well-known genome, including shared genes with humans that are impacted by exposure to radiation. A Varian TrueBeam delivered a prescribed dose of 19.2 Gy at conventional rates (CONV), while an IntraOp Mobetron simultaneously delivered UHDR matched radiation dose. Gafchromic EBTXD film was used to determine beam parameters and to verify dosimetry measurements. At the one-hour post-irradiation timepoint, root and shoot samples were collected and frozen. Shoot and root RNA were isolated using the Sigma Spectrum Total RNA Kit, treated with DNase, and submitted for RNA sequencing. Sequencing data were analyzed using iDEP v2.4.3 software.
Results
The film analysis verified an average dose of 18.76 Gy ± 1.76% for plants treated with UHDR (93.79 Gy/s) and 19.34 Gy ± 0.15% for plants treated conventionally. Quality checks after RNA isolation confirmed that all samples met the primary purity standard, having an A260/280 value around 2, along with all but one sample meeting the secondary standard for A260/230. Initial findings from the RNA sequencing of the shoots, showing relevant DNA damage repair pathways, indicate a differential response between UHDR and CONV groups. Specific genes are currently being analyzed to investigate the presence of the FLASH effect.
Conclusion
This work has informed us about CONV- and UHDR-mediated genomic responses in Arabidopsis thaliana and how they differ from animal models. This novel approach works towards isolating the mechanisms behind the FLASH effect. Because CONV and UHDR beams produced differing effects, specific gene analysis is being conducted to determine if the UHDR beam is inducing the FLASH effect.