PROBLEM TO BE SOLVED: To isolate/identify genes or proteins involving symbiosis of a plant with rhizobium and/or mycorrhizal fungi and to provide a method for utilizing the genes or the proteins. SOLUTION: Two genes involving symbiosis with rhizobium and/or mycorrhizal fungi were acquired from Lotus japonicus by using a variant which is incomplete to symbiosis with rhizobium and/or mycorrhizal fungi. Since symbiosability with rhizobium and/or mycorrhizal fungi can be imparted to other plants by using these genes and/or the proteins encoded by the genes, these genes and proteins are extremely useful. COPYRIGHT: (C)2005,JPO&NCIPI