• hypernodulation;
  • Ljrdh1;
  • Lotus japonicus;
  • root-determined.s


A mutant line that develops an excess number of small nodules was found in Lotus japonicus Miyakojima MG20 during a screening for mutants defective in nodule development and nitrogen fixation. Genetic analysis revealed that the phenotype is inherited in a monogenic, recessive manner. The gene's locus was mapped on chromosome 1 between 53.7 and 61.4 cM. This mutant formed 5–10-fold more nodules than the wild-type plant, and a grafting experiment revealed that the root regulated the hypernodulation. Except for the nodulation's phenotype no other differences were found between the mutant and the wild-type plant with respect to growth and morphological characteristics. In the mapped locus for the mutant no nodulation genes were reported, and this fact strongly suggests that the gene's locus is a new one. The gene was named root-determined hypernodulation (rdh) 1.