Hypomagnetic field inhibits seed germination via ROS signaling and reprogramming transcriptome in Arabidopsis thaliana

The geomagnetic field (GMF) is an environmental factor that influences plant growth and development. While the blue-light photoreceptor cryptochrome (CRY) is believed to serve as a magnetic-field sensor in animals, its role in plants remains unclear. Researchers created a hypomagnetic field (HMF) using Helmholtz coils and magnetic shielding to study how GMF deprivation impacts Arabidopsis thaliana.

They found that HMF slows down germination without affecting the final germination rate, indicating that it specifically regulates germination kinetics rather than seed viability. Transcriptomic analysis showed that HMF triggers a coordinated transcriptional change, leading to the downregulation of growth-promoting genes and upregulation of defense-related genes.

This shift occurred alongside a significant increase in reactive oxygen species (ROS), suggesting that redox perturbation contributes to the germination delay. ROS inhibitors such as reduced glutathione and ascorbic acid restored germination speed and the expression of some HMF-responsive genes, highlighting the central role of ROS in mediating HMF bioeffects.

Genetic studies using cry1 cry2 double mutants showed that HMF delays germination through both CRY-dependent and -independent pathways, implying the presence of additional magnetosensitive modules beyond the known CRY-based radical-pair mechanism. These findings reveal that GMF serves as a positive environmental signal that fine-tunes the growth-defense trade-off through redox-dependent signaling.