Genetius

Using Rhizophagus irregularis to connect two Medicago truncatula plants, the study shows that intact common mycelial networks transmit inter‑plant signals that alter the receiver’s leaf transcriptome and metabolome, inducing specific isoprenoid compounds. These CMN‑mediated signals increase resistance to Fusarium sporotrichoides while enhancing susceptibility to Botrytis cinerea, demonstrating pathogen‑specific effects independent of hyphal damage.

The study examined how genotype interactions among two Medicago truncatula lines, three pea aphid clonal lines, and rhizobial inoculation (Sinorhizobium meliloti) affect aphid performance and plant defence gene expression. Results showed that plant and aphid genotypes together with rhizobial symbiosis modulate SA and JA pathway activation and aphid fitness, highlighting a G×G×R effect on multitrophic interactions.

The study demonstrates that the FT paralogs MtFTb1 and MtFTb2 are redundantly required for flowering under long-day conditions in the legume Medicago truncatula. CRISPR-generated single and double mutants reveal that loss of both genes delays flowering under LD while preserving vernalization response, and transcriptomic analysis shows they up‑regulate MtFTa1 and MADS‑box genes.

The study identifies a BTB/POZ-domain protein, MtCSP1, that interacts with the ARF GTPase MtARFA1 in Medicago truncatula, linking small GTPase signaling to ubiquitin-mediated protein degradation during rhizobial infection and nodule formation. Functional analyses show that MtCSP1 is required for proper infection thread progression and nodule organogenesis, acting at late endosomal vesicles.

Using Medicago truncatula nitrate transporter mutants, the study shows that loss of NRT2.1 blocks nitrate‑induced media alkalization, while loss of NRT1.1A/B only delays this effect, indicating distinct physiological roles. Apoplastic pH initially drops during nitrate uptake in a NRT1.1A/B‑dependent manner, and the authors propose that cell‑wall buffering and H⁺‑ATPase activity offset media proton depletion, maintaining low apoplastic pH.

The study reveals that the cold‑repressed transcription factor MtCBF4 suppresses anthocyanin synthesis in Medicago truncatula by repressing MtLAP1 and modulating histone H3K27 trimethylation via activation of the demethylase MtJMJ13. MtJMJ13 further demethylates MtCBF4 and other negative regulators, creating a feedback loop that is lifted under cold stress, resulting in increased anthocyanin accumulation and improved cold tolerance.

The study combined mathematical modeling, live-cell imaging, and bacterial mutant analysis in Medicago truncatula to investigate how Sinorhizobium meliloti moves within infection threads. Results indicate that bacterial movement is slow and likely passive, with flagella-independent surface translocation driven by the rhizobactin 1021 surfactant being crucial for successful root and nodule colonization.