Authors
Chaoyan Yin, Kévin Magne, Fathi Berrabah, Dario Monachello, Gautier Bernal, Kirankumar S Mysore, Jiangqi Wen, Catherine Etchebest, Pascal Ratet, Véronique Gruber
Published in
The New phytologist. Jun 21, 2026. Epub Jun 21, 2026.
Abstract
In Medicago littoralis R-108, Symbiotic CYSTEINE-RICH RECEPTOR-LIKE KINASE (MtSymCRK) is required to prevent defense reactions in symbiotic nodules during chronic infection. MtSymCRK represents a key legume symbiotic gene controlling nodule immunity and early bacteroid survival, but its mode of action in the cell signaling remains poorly understood. This study investigated proteins interacting with MtSymCRK by screening an Arabidopsis thaliana open reading frame (ORF) library using yeast-two-hybrid followed by translational genetics towards R-108. Finally, we conducted a reverse genetic approach in R-108 using Transposon of Nicotiana tabacum 1 (Tnt1) insertional mutants. We identified a 14-3-3 protein, AtGENERAL REGULATORY FACTOR 8 (AtGRF8) interacting with MtSymCRK kinase domain (MtSymCRKKIN) and confirmed the interaction between MtSymCRKKIN and MtGRF8, the closest homolog of AtGRF8 in R-108. Moreover, other members of the 14-3-3 family interact with MtSymCRKKIN but with a lower affinity than MtGRF8. We also demonstrated that the corresponding Tnt1 mutant line Mtgrf8 displays symbiotic dysfunctions in defense and senescence responses, resulting in a reduction of bacteroid differentiation. These dysfunctions compromise the intracellular survival of the rhizobia, thereby impairing the nitrogen fixation of rhizobia. Our findings show that MtGRF8 and MtSymCRK are required for effective functioning of symbiosis and prevention of bacteroid death.
PMID:
42324605
Bibliographic data and abstract were imported from PubMed on 22 Jun 2026.
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