Near-zero magnetic field inhibits seed germination via ROS signaling and reprogramming transcriptome in Arabidopsis thaliana

The geomagnetic field (GMF) is a pervasive yet poorly understood environmental factor for plant growth and development. Here, we reveal that near-zero magnetic field (NZMF) significantly delays seed germination in Arabidopsis thaliana. Time-resolved transcriptomic analyses showed a subtle but coordinated transcriptional shift under NZMF, characterized by downregulation of growth-promoting genes and upregulation of defense-related pathways. This transcriptional reprogramming coincided with moderate accumulation of reactive oxygen species (ROS), linking redox signaling to the germination delay. Consistently, scavenging ROS partially restored germination rates and reversed differential expression of a subset of stress-responsive genes, confirming the central role of ROS in the NZMF-induced transcriptional reprogramming. Genetic analysis using cry1cry2 mutants further indicated that NZMF delays seed germination via both CRY-dependent and -independent pathways. Taken together, our findings suggest that the GMF acts as an environmental cue that fine tunes the balance between growth and defense during plant early development, likely through a redox-dependent mechanism underlying plant responses to magnetic field perturbations. These results provide a possible mechanistic insights into how paleomagnetic variations may have imposed selective pressures on the biosphere and offer a framework for assessing plant habitability in extraterrestrial environments with weak magnetic fields.