TRINITY controls nodulation and mycorrhization concomitantly in Lotus japonicus

Abstract

Recent genetic analyses of the symbiotic processes in legume revealed that several steps are common for rhizobial nodulation and arbuscular mycorrhization. A symbiotic mutant of Lotus japonicus, Ljsym71, is the non-nodulating mutant. Nod factor could not induce calcium spiking and internal hyphae of arbuscular fungi could not penetrate into cortex. We have named the causative factor as TRINITY (TRI), after the fact of a tripartite relationship among Legume-Rhizobia-Arbuscular mycorrhiza symbioses. We constructed BAC/TAC contig around TRIlocus. Genetic markers within the contig were developed and used for delimiting the locus to approx. 155kb. Among 4 candidate genes, we have identified TRI, which is a novel gene and does not include any domain with known function. We have isolated 14 alleles of tri induced by EMS and somaclonal mutation. The latter mutation showed 100b-2kb deletion in TRI locus, indicated that the region is a hot spot of heterozygous deletion.