title: Shoot-derived cytokinins systemically regulate root nodulation.
abstract: Legumes establish symbiotic associations with nitrogen-fixing bacteria (rhizobia) in root nodules to obtain nitrogen. Legumes control nodule number through long-distance communication between roots and shoots, maintaining the proper symbiotic balance. Rhizobial infection triggers the production of mobile CLE-RS1/2 peptides in Lotus japonicus roots; the perception of the signal by receptor kinase HAR1 in shoots presumably induces the production of an unidentified shoot-derived inhibitor (SDI) that translocates to roots and blocks further nodule development. Here we show that, CLE-RS1/2-HAR1 signalling activates the production of shoot-derived cytokinins, which have an SDI-like capacity to systemically suppress nodulation. In addition, we show that LjIPT3 is involved in nodulation-related cytokinin production in shoots. The expression of LjIPT3 is activated in an HAR1-dependent manner. We further demonstrate shoot-to-root long-distance transport of cytokinin in L. japonicus seedlings. These findings add essential components to our understanding of how legumes control nodulation to balance nutritional requirements and energy status.
authors.affiliation: 1] Division of Symbiotic Systems, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan [2] Department of Basic Biology in the School of Life Science of the Graduate University for Advanced Studies, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Takema
authors.initials: T
authors.lastname: Sasaki
authors.affiliation: 1] Division of Symbiotic Systems, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan [2] Department of Basic Biology in the School of Life Science of the Graduate University for Advanced Studies, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Suzaki
authors.affiliation: Division of Symbiotic Systems, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Soyano
authors.affiliation: Plant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama 230-0045, Japan.
authors.forename: Mikiko
authors.initials: M
authors.lastname: Kojima
authors.affiliation: Plant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama 230-0045, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakakibara
authors.affiliation: 1] Division of Symbiotic Systems, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan [2] Department of Basic Biology in the School of Life Science of the Graduate University for Advanced Studies, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kawaguchi
mesh_terms: D001692:Biological Transport; D003583:Cytokinins / Q000378:metabolism*; D007887:Fabaceae / Q000502:physiology*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D008024:Ligands; D000070116:Lotus / Q000502:physiology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012231:Rhizobium / Q000378:metabolism
chemical_list: D003583:Cytokinins; D008024:Ligands; D010455:Peptides; D010937:Plant Growth Regulators