HAR1 mediates systemic regulation of symbiotic organ development.
Symbiotic root nodules are beneficial to leguminous host plants; however, excessive nodulation damages the host because it interferes with the distribution of nutrients in the plant. To keep a steady balance, the nodulation programme is regulated systemically in leguminous hosts. Leguminous mutants that have lost this ability display a hypernodulating phenotype. Through the use of reciprocal and self-grafting studies using Lotus japonicus hypernodulating mutants, har1 (also known as sym78), we show that the shoot genotype is responsible for the negative regulation of nodule development. A map-based cloning strategy revealed that HAR1 encodes a protein with a relative molecular mass of 108,000, which contains 21 leucine-rich repeats, a single transmembrane domain and serine/threonine kinase domains. The har1 mutant phenotype was rescued by transfection of the HAR1 gene. In a comparison of Arabidopsis receptor-like kinases, HAR1 showed the highest level of similarity with CLAVATA1 (CLV1). CLV1 negatively regulates formation of the shoot and floral meristems through cell-cell communication involving the CLV3 peptide. Identification of hypernodulation genes thus indicates that genes in leguminous plants bearing a close resemblance to CLV1 regulate nodule development systemically, by means of organ-organ communication.
Nishimura
Rieko
R
Department of Life Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 163-8902, Japan.
Hayashi
Masaki
M
Wu
Guo-Jiang
GJ
Kouchi
Hiroshi
H
Imaizumi-Anraku
Haruko
H
Murakami
Yasuhiro
Y
Kawasaki
Shinji
S
Akao
Shoichiro
S
Ohmori
Masayuki
M
Nagasawa
Mamoru
M
Harada
Kyuya
K
Kawaguchi
Masayoshi
M
D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000032:analysis / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D000070116:Lotus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009586:Nitrogen Fixation; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000032:analysis / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics; D015398:Signal Transduction; D013025:Glycine max / Q000737:chemistry / Q000235:genetics; D013559:Symbiosis; D019737:Transplants
D029681:Arabidopsis Proteins; D018744:DNA, Plant; D018749:RNA, Plant; D020794:Receptor Protein-Tyrosine Kinases; C118166:CLV1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases