Two Lotus japonicus symbiosis mutants impaired at distinct steps of arbuscule development
Martin Groth, Sonja Kosuta, Caroline Gutjahr, Kristina Haage, Simone Liesel Hardel, Miriam Schaub, Andreas Brachmann, Shusei Sato, Satoshi Tabata, Kim Findlay, Trevor L. Wang, Martin Parniske
Arbuscular mycorrhiza (AM) fungi form nutrient-acquiring symbioses with the majority of higher plants. Nutrient exchange occurs via arbuscules, highly branched hyphal structures that are formed within root cortical cells. With a view to identify host genes involved in AM development, we isolated Lotus japonicus AM-defective mutants via a microscopic screen of an EMS-mutagenized population. A standardized mapping procedure was developed that facilitated positioning the defective loci on the genetic map of L. japonicus and, in five cases, identification of mutants of known symbiotic genes. Two additional mutants representing independent loci did not form mature arbuscules during symbiosis with two divergent AM fungal species, but exhibited signs of premature arbuscule arrest or senescence. Marker gene expression patterns indicated that the two mutants are affected in distinct steps of arbuscule development. Both mutants formed wild type-like root nodules upon inoculation with Mesorhizobium loti, indicating that the mutated loci are essential during AM but not during root nodule symbiosis.
link to publishers website: DOI: 10.1111/tpj.12220