Abstract EANA2026-246

Phenotypic Performance and Molecular Stress Responses of the Pioneer Plant Arabis alpina Cultivated on Lunar Regolith for Space Agriculture

Rengin OZGUR UZILDAY, Nil DEMIRCAN, Onur KAYABASI, Tansel KAYGISIZ, Tolga YALCINKAYA, Baris UZILDAY

(1) Department of Biology, Faculty of Science, Ege University, Izmir, Türkiye

(2)Department of Horticulture, Faculty of Agriculture, Ege University, Izmir, Türkiye

 

The establishment of sustainable bioregenerative life support systems is a crucial for long-duration space exploration and the sustained human presence on the Moon and Mars. These systems require reliable crop production that operates independently of terrestrial soil resources due to the high cost and limited capacity of transporting growth substrates from Earth. Therefore, space agriculture must rely on in situ resources like lunar regolith. However, utilizing regolith presents severe, multi-faceted abiotic challenges including extreme nutrient limitation and unfavorable physical properties that can compromise physiological performance and restrict normal plant growth and development.

Cultivating pioneer plants, particularly extremophytes, offers a critical strategy for the phytoremediation of regolith and the eventual realization of extraterrestrial agriculture. In this study, phenotypic responses of three pioneer plant species Schrenkiella parvula (an extreme halophyte), Noccaea caerulescens (a metal hyperaccumulator), and Arabis alpina (a UV-B tolerant species) were evaluated on a lunar regolith simulant (LHS-1) and standard horticultural soil, under water-only and Wamelink nutrient solution irrigation. After a five-week growth period, early-stage plant responses were characterized using integrated phenotyping of growth and chlorophyll a fluorescence-based photosystem II (PSII) performance. Among the pioneer plants evaluated, A. alpina exhibited superior plant growth and phenotypic traits in the lunar regolith.

Following these promising results, we further investigated the molecular stress responses of the extremophyte A. alpina exposed to regolith simulants. High-throughput transcriptomic profiling was employed to identify key differentially expressed genes (DEGs) and delineate the underlying regulatory networks. Gene Ontology (GO) and KEGG functional enrichment analyses of the significantly upregulated DEGs revealed a strong overrepresentation of pathways related to broad stimulus responses, jasmonic acid (JA) metabolic processes, and specialized secondary metabolism. Notably, the transcriptomic data indicated the activation of a robust, systemic wound-like defense response. This was characterized by the profound upregulation of key JA biosynthesis and signaling components, including AOC2, CYP94D2, and JAZ10 (JAS1). Furthermore, promoter sequence analysis identified a highly significant enrichment of the G-box motif (CACGTG) among these responsive genes, strongly pointing to a central regulatory role for MYC transcription factors in mediating multistress resilience under spaceflight-relevant conditions.

Alongside JA-mediated defense cascades, the analysis highlighted a critical adjustment in mitochondrial redox and respiratory homeostasis. Genes encoding alternative oxidases, specifically AOX1B (log2FC 8.72) and NDB4, were among the most highly upregulated transcripts in the nuclear module. This suggests that the activation of alternative respiratory pathways is a primary mechanism utilized by the plant to maintain cellular equilibrium and manage energy flows during regolith-induced stress.

In conclusion, our findings demonstrate that cultivation on lunar regolith simulants triggers a comprehensive stress response in A. alpina that heavily relies on jasmonate signaling and alternative respiration. Understanding these core molecular mechanisms provides vital insights into extremophyte tolerance strategies, ultimately guiding the selection and molecular optimization of robust plant species for future space agriculture.

This work is funded by the Scientific and Technological Research Council of Türkiye (TÜBİTAK) to ROU (Grant no: 124Z672).