Identification of Bradyrhizobium elkanii USDA61 Type III Effectors Determining Symbiosis with Vigna mungo

Genes

Michiko Yasuda¹  HienP. Nguyen²  Neung Teaumroong³  Shin Okazaki⁴  SafirahT. N. Ratu⁴ 

[1] Graduate School of Agriculture, TUAT, Fuchu, Tokyo 183-8509, Japan;Institute of Global Innovation Research (IGIR), Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8538, Japan;School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology (SUT), Ratchasima 30000, Thailand;United Graduate School of Agricultural Science, TUAT, Fuchu, Tokyo 183-8509, Japan;

关键词: symbiosis;    T3SS;    effectors;    NopL;    Vigna mungo;    Bradyrhizobium elkanii;   

DOI  :  10.3390/genes11050474

来源: DOAJ

【 摘 要 】

Bradyrhizobium elkanii USDA61 possesses a functional type III secretion system (T3SS) that controls host-specific symbioses with legumes. Here, we demonstrated that B. elkanii T3SS is essential for the nodulation of several southern Asiatic Vigna mungo cultivars. Strikingly, inactivation of either Nod factor synthesis or T3SS in B. elkanii abolished nodulation of the V. mungo plants. Among the effectors, NopL was identified as a key determinant for T3SS-dependent symbiosis. Mutations of other effector genes, such as innB, nopP2, and bel2-5, also impacted symbiotic effectiveness, depending on host genotypes. The nopL deletion mutant formed no nodules on V. mungo, but infection thread formation was still maintained, thereby suggesting its pivotal role in nodule organogenesis. Phylogenetic analyses revealed that NopL was exclusively conserved among Bradyrhizobium and Sinorhizobium (Ensifer) species and showed a different phylogenetic lineage from T3SS. These findings suggest that V. mungo evolved a unique symbiotic signaling cascade that requires both NFs and T3Es (NopL).

【 授权许可】

Unknown