Abstract
Legumes are capable of establishing root symbiosis with rhizobia and form root-derived organs, called nodules. In model legume Lotus japonicus, nodule number is controlled by long-distance signaling mediated by HAR1 that is a CLAVATA1-like LRR-RLK and thought to function in the shoot.
The Lotus mutant klavier (klv) exhibits a typical hypernodulation phenotype. KLV encodes leucine-rich repeat receptor-like kinase (LRR-RLK). Based on the grafting experiments, KLV is thought to function in the shoot to mediate the long-distance negative regulation of nodulation like HAR1.
Double mutant analysis indicates that KLV functions in the same genetic pathway as HAR1 to control the negative regulation of nodulation.
It has been shown that over-expression of either of the two CLE peptide genes LjCLE-RS1 or LjCLE-RS2 suppresses nodulation systemically via HAR1. The klv mutants with transgenic hairy roots where LjCLE-RS1 or -RS2 were over-expressed exhibited typical hypernodulating phenotypes. These results indicate that KLV is also required for the LjCLE-RS1/-RS2-mediated negative regulation of nodulation, as is the case with HAR1.
