Abstract
Nodule development in leguminous plants is induced by Nod factors secreted by rhizobia. Plant mutants unable to form nodule primordia involving cortical cell division are called as non-nodulation (Nod-) mutants. Nod- mutants have defects in some components of Nod factor signaling pathway ranging from Nod factor perception to gene expression. In Lotus japonicus, ten genes responsible for this pathway have been identified. In order to isolate a novel mutant with some genomic deletion, we attempted ion beam mutagenesis using an early flowering ecotype Miyakojima MG-20. Irradiation of C6+ at 80 Gy resulted in successful isolation of 5 Nod- mutants. Among them a mutant 3122 has 1,366 bp deletion in MtNsp1-like sequence of L. japonicus. The LjNsp1 gene encodes a putative transcription factor of the GRAS family. The expression analysis of LjNsp1 and the interaction with LjNSP2 in yeast two hybrid system will be reported.
