LjSYM30, the Final Gene of Common Signaling Pathway is Required for Invasion of Rhizobia and Arbuscular Mycorrhizal Fungi

Abstract

Recently, it has been revealed that several genes are required for symbiosis with both rhizobia and arbuscular mycorrhizal fungi by symbiotic mutant analyses of legume plants. When Ljsym30, one of these mutants of Lotus japonicus was infected with Mesorhizobium loti, it formed many bumps. But it failed to develop mature nodules. M. loti could colonize at curling spot of root hair, but could not invade the plant cell. When the mutant was infected with Glomus intraradices, internal hyphae were developed in cortex, but early senescence of arbuscules was induced. Putative protein of LjSYM30 consisted of 518 amino acid residues. This product did not possess any known domain. When promoter activity of LjSYM30 was investigated by GUS analysis, GUS activity was observed in a region undergoing cortical cell division and in nodules. It was suggested that LjSYM30:GFP was localized in nuclei. From these results, we discuss the function of LjSYM30.