title: Too much love, a novel Kelch repeat-containing F-box protein, functions in the long-distance regulation of the legume-Rhizobium symbiosis.
abstract: The interaction of legumes with N2-fixing bacteria collectively called rhizobia results in root nodule development. The number of nodules formed is tightly restricted through the systemic negative feedback control by the host called autoregulation of nodulation (AON). Here, we report the characterization and gene identification of TOO MUCH LOVE (TML), a root factor that acts during AON in a model legume Lotus japonicus. In our genetic analyses using another root-regulated hypernodulation mutant, plenty, the tml-1 plenty double mutant showed additive effects on the nodule number, whereas the tml-1 har1-7 double mutant did not, suggesting that TML and PLENTY act in different genetic pathways and that TML and HAR1 act in the same genetic pathway. The systemic suppression of nodule formation by CLE-RS1/RS2 overexpression was not observed in the tml mutant background, indicating that TML acts downstream of CLE-RS1/RS2. The tml-1 Snf2 double mutant developed an excessive number of spontaneous nodules, indicating that TML inhibits nodule organogenesis. Together with the determination of the deleted regions in tml-1/-2/-3, the fine mapping of tml-4 and the next-generation sequencing analysis, we identified a nonsense mutation in the Kelch repeat-containing F-box protein. As the gene knockdown of the candidate drastically increased the number of nodules, we concluded that it should be the causative gene. An expression analysis revealed that TML is a root-specific gene. In addition, the activity of ProTML-GUS was constitutively detected in the root tip and in the nodules/nodule primordia upon rhizobial infection. In conclusion, TML is a root factor acting at the final stage of AON.
authors: Department of Basic Biology in the School of Life Science of the Graduate University for Advanced Studies, Aichi, Japan.
authors: Masahiro
authors: M
authors: Takahara
authors: Shimpei
authors: S
authors: Magori
authors: Takashi
authors: T
authors: Soyano
authors: Satoru
authors: S
authors: Okamoto
authors: Chie
authors: C
authors: Yoshida
authors: Koji
authors: K
authors: Yano
authors: Shusei
authors: S
authors: Sato
authors: Satoshi
authors: S
authors: Tabata
authors: Katsushi
authors: K
authors: Yamaguchi
authors: Shuji
authors: S
authors: Shigenobu
authors: Naoya
authors: N
authors: Takeda
authors: Takuya
authors: T
authors: Suzaki
authors: Masayoshi
authors: M
authors: Kawaguchi
mesh_terms: D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism*; D007887:Fabaceae / Q000378:metabolism* / Q000382:microbiology*; D000070116:Lotus / Q000378:metabolism / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D055170:Plant Root Nodulation / Q000235:genetics / Q000502:physiology; D012231:Rhizobium / Q000502:physiology*; D053204:Root Nodules, Plant / Q000235:genetics / Q000378:metabolism; D013559:Symbiosis / Q000235:genetics / Q000502:physiology
chemical_list: D044783:F-Box Proteins; D010940:Plant Proteins