The Artemis I mission reshaped seed amino acid composition and post-flight plant growth in a genotype-dependent manner

Plants will be critical to sustainable life support during long-duration space exploration, yet the effects of deep-space exposure on seed metabolism and plant growth remain unclear. Using Arabidopsis thaliana germplasm with altered branched-chain amino acid (BCAA) biosynthesis, we examined the impact of the Artemis I mission environment on seed amino acid composition, viability, and post-flight plant performance. We found that the Artemis I mission induced genotype-dependent change in seed free amino acid profiles, with a BCAA-enriched mutant, ipms1 , showing increased levels of essential amino acids, whereas wild type and other BCAA-altered mutants, ahass2 and omr1 , were largely unaffected. Despite these metabolic changes, seed viability and germination efficiency were preserved across all genotypes. In contrast, the Artemis I mission triggered pronounced, genotype-specific alterations in free amino acid homeostasis during early seedling development, and it promoted enhanced rosette growth in wild type and ipms1 , but not in ahass2 or omr1 . Together, these findings identify BCAA metabolism as an important factor influencing plant metabolic and growth responses related to deep-space exposure conditions, with implications for germplasm selection in future lunar and Mars missions.