Spatiotemporal co-transcriptomics uncovers coordinated rhizobia-legume stress programs supporting nitrogen fixation in Medicago.

Reactive oxygen species (ROS)-associated stress responses in both host cells and rhizobia are linked to symbiotic nitrogen fixation in Medicago nodules.

• Why it matters: Understanding how stress signaling influences nitrogen fixation can reveal mechanisms to improve legume productivity and sustainable agriculture, addressing gaps in knowledge about host-microbe coordination.
• What they did: The study used spatial enhanced resolution omics sequencing (Stereo-seq) on Medicago nodules across five developmental stages, detecting host and rhizobial transcripts simultaneously within tissue sections.
• The result: Findings show that ROS-related stress responses are stage- and zone-specific and that transcription factors MtERF71 and MtCBF1 promote nitrogen fixation by regulating ROS homeostasis and activating symbiotic genes.