Expression of the CLE-RS3 gene suppresses root nodulation in Lotus japonicus.
Cell-to-cell communication, principally mediated by short- or long-range mobile signals, is involved in many plant developmental processes. In root nodule symbiosis, a mutual relationship between leguminous plants and nitrogen-fixing rhizobia, the mechanism for the autoregulation of nodulation (AON) plays a key role in preventing the production of an excess number of nodules. AON is based on long-distance cell-to-cell communication between roots and shoots. In Lotus japonicus, two CLAVATA3/ESR-related (CLE) peptides, encoded by CLE-ROOT SIGNAL 1 (CLE-RS1) and -RS2, act as putative root-derived signals that transmit signals inhibiting further nodule development through interaction with a shoot-acting receptor-like kinase HYPERNODULATION ABERRANT ROOT FORMATION 1 (HAR1). Here, an in silico search and subsequent expression analyses enabled us to identify two new L. japonicus CLE genes that are potentially involved in nodulation, designated as CLE-RS3 and LjCLE40. Time-course expression patterns showed that CLE-RS1/2/3 and LjCLE40 expression is induced during nodulation with different activation patterns. Furthermore, constitutive expression of CLE-RS3 significantly suppressed nodule formation in a HAR1-dependent manner. TOO MUCH LOVE, a root-acting regulator of AON, is also required for the CLE-RS3 action. These results suggest that CLE-RS3 is a new component of AON in L. japonicus that may act as a potential root-derived signal through interaction with HAR1. Because CLE-RS2, CLE-RS3 and LjCLE40 are located in tandem in the genome and their expression is induced not only by rhizobial infection but also by nitrate, these genes may have duplicated from a common gene.
National Institute for Basic Biology, Okazaki, 444-8585, Japan.|School of Life Science, The Graduate University for Advanced Studies, Okazaki, 444-8585, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan.
Hanna
H
Nishida
National Institute for Basic Biology, Okazaki, 444-8585, Japan.
Yoshihiro
Y
Handa
National Institute for Basic Biology, Okazaki, 444-8585, Japan.
Sachiko
S
Tanaka
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan. suzaki.takuya.fn@u.tsukuba.ac.jp.
Takuya
T
Suzaki
National Institute for Basic Biology, Okazaki, 444-8585, Japan. masayosi@nibb.ac.jp.|School of Life Science, The Graduate University for Advanced Studies, Okazaki, 444-8585, Japan. masayosi@nibb.ac.jp.
Masayoshi
M
Kawaguchi
D000595:Amino Acid Sequence; D003583:Cytokinins / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D000070116:Lotus / Q000187:drug effects / Q000235:genetics*; D009566:Nitrates / Q000494:pharmacology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D055170:Plant Root Nodulation / Q000187:drug effects / Q000235:genetics*; D030821:Plants, Genetically Modified; D060888:Real-Time Polymerase Chain Reaction; D053204:Root Nodules, Plant / Q000187:drug effects / Q000378:metabolism; D014170:Transformation, Genetic
D003583:Cytokinins; D009566:Nitrates; D010940:Plant Proteins
Autoregulation of nodulation; CLE; Legume; Lotus japonicus; Nodulation; Root nodule symbiosis