Analysis of TRINITY gene that governs rhizobial and mycorrhizal symbioses

Abstract

We have isolated the TRINITY (TRI) gene from a symbiotic mutant Ljsym71 that controls the symbioses of rhizobia and mycorrhiza. The predicted amino acid sequence has revealed that TRI has a plastid-transit peptide and four transmembrane domains, and is homologous to potassium transport proteins. TRI is presumed to have a critical role in the signal transduction pathway because symbiotic responses of Ljsym71 are completely repressed in the early stage of nodulation. Southern hybridization analysis has shown the existence of a TRI homologue, and we have successfully isolated this gene, Sister of TRINITY (SOT). Because SOT also has a plastid-transit peptide and was assumed to present with TRI, the relationship of symbiosis and interaction with TRI are expected. TRI homologs are widely distributed in leguminous and non-leguminous plants. This fact indicates that the function of TRI plays an important role in not only symbiosis, but also general intracellular events.