Plant-based life support systems: priming plants’ adaptation to the Moon through ionizing radiation within the PRIMO project

Human space exploration is progressively moving toward long-duration missions and permanent human presence on the Moon and Mars. Achieving these ambitious goals requires overcoming major scientific and technological challenges. Among these, habitability requires the development of Bioregenerative Life Support Systems (BLSS), capable of regenerating essential resources and reducing resupply from Earth. Within BLSS, higher plants play a central role, contributing to oxygen production, carbon dioxide removal, water purification, waste recycling, and fresh food supply. The cultivation of plants in space also supports human well-being by alleviating psychological and physiological stress of prolonged isolation and confinement. In fact, the green environments, apart from filtering airborne contaminants, improve psychological relief, emotional stability, and enhance cognitive functions while reducing pain perception. Moreover, the introduction of fresh food in astronauts’ diet contributes to a more balanced diet rich in active compounds, including vitamins, antioxidants, and polyphenols, with both physiological and psychological benefits.

Therefore, plant cultivation in space is increasingly recognized as a key element for crew support by the International Space Exploration Coordination Group (ISECG) within the priority areas, “Life Support and Habitability” and “Crew Health and Performance”.

One of the most critical constraints in extraterrestrial environments is exposure to high levels of ionizing radiation (IR) that significantly influences organism growth and development through molecular alterations, disrupted morphogenesis, and physiological stress responses

Although it is well documented that plants are much more resistant to IR compared to animals, IR can still compromise the efficiency of plants as resource regenerators in BLSS and alter the balance of inputs and outputs among the sub-compartments. Therefore, a thorough understanding of plant responses to radiation is essential for the design and optimization of space greenhouses. However, the exposure to IR at specific doses can enhance plant defense mechanisms, inducing a pre-acclimation response that increases tolerance to subsequent stresses. The PRIMO Project (Priming Radiation-Induced plants’ adaptation to MOon: make an enemy your friend), selected by the European Space Agency (ESA) within the ESA SciSpacE AO - Reserve Pool Of Science Activities for the Moon aims to investigate whether the pre-irradiation of seeds on Earth can enhance plant resistance to the Moon’s environment. The Italian Space Agency (ASI) has funded the preparation of the pre-flight phase of the project, in which seeds of different plant species will be pre-irradiated on Earth using different types and doses of ionizing radiation. Both treated and non-treated (control) seeds will be exposed to the Lunar radiation conditions and reduced gravity throughout the mission duration. After sample recovery, cultivation trials will be conducted under controlled conditions on Earth. Plant performance will be evaluated through growth analysis, transcriptomic profiling, physiological and anatomical assessments, and nutritional quality measurements, providing insights into the feasibility of radiation-based strategies to support sustainable plant cultivation in future lunar BLSS. The approach of PRIMO will allow exploiting the beneficial effects of low-dose radiation to enhance plant tolerance to abiotic stresses, transforming IR from a limiting factor into a potential tool to improve plant resilience to space-related stressors.