The identification of novel loci required for appropriate nodule development in Medicago truncatula

摘要: The formation of functional symbiotic nodules is the result a coordinated developmental program between legumes and rhizobial bacteria. Genetic analyses in have been used to dissect signaling processes required for establishing legume-rhizobial endosymbiotic association. Compared early events interaction, less attention has paid plant loci colonization functioning nodule. Here we describe identification characterization number new genetic Medicago truncatula that are development effective nitrogen fixing nodules. Approximately 38,000 EMS fast neutron mutagenized seedlings were screened defects fixation. Mutant plants impaired nodule efficient fixation selected further phenotypic analysis. Nine mutants completely lacking (Nod-) represented six complementation groups which two novel identified. Eight with ineffective (Fix-) seven groups, out five monogenic loci. Fix- M. showed symptoms deficiency developed small white Microscopic analysis revealed release rhizobia from infection threads, differentiation maintenance persistence bacteria cells. Additionally, monitored transcriptional activity symbiosis specific genes define what stage process blocked each mutants. Based on gene expression hierarchy FIX proposed. isolated this study provide foundation mechanisms underpinning nodulation, particular later stages associated bacterial function.