Physical interaction analyses of leucine-rich repeat receptor-like kinases HAR1 and KLV that control the long-distance negative regulation of nodulation in Lotus japonicus

Abstract

Leguminous plants develop root nodules to establish the endosymbiosis with nitrogen-fixing bacteria. We have reported the identification of a novel leucine-rich repeat receptor-like kinase (LRR-RLK), KLAVIER (KLV), which negatively and systemically controls the number of nodules in Lotus japonicus. In leaf, KLV was predominantly expressed in the vascular tissues, as with another LRR-RLK gene, HAR1, which also regulates nodule number. Genetic analyses indicated that KLV and HAR1 function in the same genetic pathway to govern the negative regulation of nodulation, and are epistatic to the effect of overexpression of LjCLE-RS1 or LjCLE-RS2 that suppresses nodulation.
In this study, transient expression analysis in Nicotiana benthamiana indicated the physical interaction of KLV and HAR1. These results suggest that the potential KLV-HAR1 receptor complex regulates symbiotic nodulation transmitting the root-derived signals.