Rhizobial type III secretion system and symbiosis with legumes
S. OKAZAKI (1) (1) Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Japan

Root-nodule symbiosis between leguminous plants and nitrogen-fixing bacteria (rhizobia) involves molecular communication between the two partners. Key components for the establishment of symbiosis are rhizobium-derived lipochitooligosaccharides (Nod factors, NFs) and their leguminous receptors (NFRs) that initiate nodule development and bacterial entry. Previously, we demonstrated that symbiosis in the soybean rhizobium Bradyrhizobium elkanii is promoted by the type III secretion system (T3SS), which delivers virulence factors via pathogenic bacteria. Intriguingly, T3SS of B. elkanii activates host nodulation signaling in the absence of NFs and NFRs. In contrast, T3SS of B. elkanii causes nodulation restriction on soybeans carrying Rj4 allele. We have identified several T3SS-related genes in B. elkanii that affect symbiotic interactions with host legumes. Functional properties and symbiotic roles of the novel T3SS-related genes will be discussed.


Abstract Number: C7-1
Session Type: Concurrent