Genetius

The study identifies the pseudokinase CRN in Medicago truncatula as a regulator of inflorescence meristem branching and a negative modulator of root interactions with arbuscular mycorrhizal (AM) fungi, operating partially independently of the AM autoregulation CLE peptide MtCLE53. Transcriptomic profiling of crn mutant roots reveals disruptions in nutrient, symbiosis, and stress signaling pathways, highlighting the multifaceted role of MtCRN in plant development and environmental interactions.

A forward-genetic screen in Medicago truncatula identified the dlm1 mutant, which reverses the normal day-night leaflet movement pattern. The study shows that DLM1 encodes a nuclear PP2C phosphatase with dual phosphatase/kinase domains, and that its phosphatase activity is essential for proper motor cell volume changes and leaflet movement. Phylogenetic and structural analyses suggest DLM1’s function is conserved across legume species displaying rhythmic leaflet movements.

The study identifies the legume‑specific GBP1 gene as a negative regulator of symbiotic nitrogen fixation, which reduces bacterial nitrogenase activity within Medicago truncatula nodules. Inactivating GBP1 enhances nitrogen fixation without altering nodule number or development, suggesting a target for engineering more productive legumes.

The study employs a dual‑colour Medicago histone reporter to resolve cell‑cycle dynamics in root cortex cells during root nodule symbiosis, revealing that cells traversed by infection threads adopt a distinct cell‑cycle stage characterized by nuclear widening and chromatin reorganization indicative of exit from division. Fluorescent cell‑cycle phase reporters confirm reduced proliferation and altered G2/M transition, likely mediated by NF‑YA1, underpin successful rhizobial delivery to nodule cells.

The study investigates how genetically distinct Medicago truncatula genotypes modulate non‑additive interactions with multiple mutualistic microbes under both benign and pathogenic conditions. Using a large‑scale manipulative microbiome experiment combined with performance measurements, survival analysis, predictive modeling, and gene expression profiling, the authors find that tolerant genotypes gain greater benefits from mutualists, that these benefits persist across environments, and that symbiotic quality predicts disease survival. The findings suggest that fostering synergistic plant‑microbe interactions could enhance crop yields and disease resistance while reducing agrochemical reliance.

The study investigated whether nitrogen‑fixing rhizobial symbiosis in Medicago truncatula primes defense against the pea aphid Acyrthosiphon pisum. Metabolite profiling (LC‑MS, GC‑MS) and qPCR revealed that symbiotic plants uniquely accumulated triterpenoid saponins and up‑regulated flavonoid‑biosynthetic genes after aphid infestation, suggesting that NFS enhances pest‑specific defenses.