Receptors complex associated with defense and symbiotic signaling in legumes
F. FENG (1), J. Sun (2), S. Radutoiu (3), J. Stougaard (4), G. Oldroyd (2) (1) John Innes Centre, United Kingdom; (2) John Innes Centre, United Kingdom; (3) Department of Molecular Biology and Genetics, Centre for Carbohydrate Recognition and Signalling,Aarhus University, Denmark; (4) Department of Molecular Biology and Genetics, Centre for Carbohydrate Recognition and Signalling,Aarhus University, United Kingdom

Chitin oligosaccharides from fungal cell walls can be perceived by plant pattern recognition receptors to activate PAMP-triggered immunity (PTI) and this plays an important role during plant resistance to potential pathogens. Previous research has defined that lysin motif (LysM)-containing receptor-like kinases (LysM-RLKs) are involved in chitin perception for activation of PTI in Arabidopsis and rice. Closely related LysM-RLKs in legumes function in the perception of chito-oligosaccharides from beneficial nitrogen-fixing rhizobia bacteria. Our research aims to clarify the molecular mechanisms involved in the activation of PAMP versus symbiotic signaling by closely related signaling molecules. We found that long-chain chitin oligomers CO8 can trigger ROS production and MAPK phosphorylation and activate the resistance to fungal pathogen in the model legume Medicago truncatula. We also demonstrated that CO8 is a symbiotic elicitor to induce nuclear calcium spiking in legumes. There are large members of the LysM-RLK family in M. truncatula, many more than are present in Arabidopsis or rice, and this likely reflects an expanded function for these LysM-RLKs for activation of symbiosis signaling in legumes. Reverse genetic screening in both Lotus japonicus and M. truncatula revealed multiple LysM-RLK mutants with defects in CO8-induced PAMP and symbiosis signaling. These chitin receptors are closely related to, but different to the Nod factor receptors associated with perception of rhizobia. Our results suggest a complex of LysM-RLKs in legume roots that function in chitin perception and a separate complex of LysM-RLKs associated with Nod factor perception.

Abstract Number: P1-4
Session Type: Poster