Response of Arabidopsis thaliana and Mizuna Mustard Seeds to Simulated Space Radiation Exposures

Abstract

One of the major concerns for long-term exploration missions beyond the Earth’s magnetosphere is consequences from exposures to solar particle event (SPE) protons and galactic cosmic rays (GCR). For long-term crewed Lunar and Mars explorations, the production of fresh food in space will provide both nutritional supplements and psychological benefits to the astronauts. However, the effects of space radiation on plants and plant propagules have not been sufficiently investigated and characterized. In this study, we evaluated the effect of two different compositions of charged particles-simulated GCR, and simulated SPE protons on dry and hydrated seeds of the model plant Arabidopsis thaliana and the crop plant Mizuna mustard [Brassica rapa var. japonica]. Exposures to charged particles, simulated GCRs (up to 80 cGy) or SPEs (up to 200 cGy), were performed either acutely or at a low dose rate using the NASA Space Radiation Laboratory (NSRL) facility at Brookhaven National Lab (BNL). Control and irradiated seeds were planted in a solid phytogel and grown in a controlled environment. Five to seven days after planting, morphological parameters were measured to evaluate radiation-induced damage in the seedlings. After exposure to single types of charged particles, as well as to simulated GCR, the hydrated Arabidopsis seeds showed dose- and quality-dependent responses, with heavier ions causing more severe defects. Seeds exposed to simulated GCR (dry seeds) and SPE (hydrated seeds) had significant, although much less damage than seeds exposed to heavier and higher linear energy transfer (LET) particles. In general, the extent of damage depends on the seed type.

Simulated galactic cosmic ray exposure activates dose-dependent DNA repair response and down regulates glucosinolate pathways in arabidopsis seedlings

“…Previously, it was found that GCR impact hydrated Arabidopsis seeds in a dose dependent and quality dependent manner ( Zhang et al., 2022 ). To complement that study and to broaden the understanding of plant response to radiation exposure, 10-day-old Arabidopsis seedlings were exposed to simulated GCRs.…”

“…Deep space radiation is composed primarily of solar particle events (SPEs) and galactic cosmic rays (GCR). Cosmic rays (GCR and SPEs) consist of approximately 85-90% protons, and 10-13% helium ions (alpha particles), with the remaining 1-2% consisting of high-atomic number and energy (HZE) nuclei particles and electrons ( Townsend, 2005 ; Zhang et al, 2022 ). For future missions to the Moon or to Mars, astronauts and other biological organisms onboard these missions will be exposed constantly to GCR and occasionally to radiation from large SPEs.…”

Strategies, Research Priorities, and Challenges for the Exploration of Space Beyond Low Earth Orbit

“…In deep space, GCR is present as an extremely low dose background radiation, which may have less impact on short term plant growth experiments. For example, the maximum accumulative GCR dose is in the milli Gray (mGy) range for a 10-day exposure, and earth-based studies have demonstrated that 290 mGy of simulated GCR did not reduce the germination rate of Arabidopsis seeds and did not significantly alter the length of the roots of the seedlings from the germinated seeds [Zhang et al, 2022]. Thus, for imbibed seeds, protons released from a large SPE pose a more significant impact than GCR.…”

Optimising plant form and function for controlled environment agriculture in space and on earth

“…Similarly, radiation exposure at the surface is elevated without atmosphere principally due to galactic cosmic radiation and solar energetic particles. 14,15 Plants and humans will need protection from these extremes when settlements are established on the moon, Mars, and elsewhere. Growth habitats will consequently either have to be underground or heavily insulated, meaning that lighting for plants will be filtered or generated from LEDs.…”

“…The ability to trap the sun's energy is limited by the absence of atmosphere, so temperatures on the moon can range from 121°C in daylight to −133°C at night near the equator. Similarly, radiation exposure at the surface is elevated without atmosphere principally due to galactic cosmic radiation and solar energetic particles 14,15 . Plants and humans will need protection from these extremes when settlements are established on the moon, Mars, and elsewhere.…”