title: Differential TOR activation and cell proliferation inArabidopsisroot and shoot apexes.
abstract: The developmental plasticity of plants relies on the remarkable ability of the meristems to integrate nutrient and energy availability with environmental signals. Meristems in root and shoot apexes share highly similar molecular players but are spatially separated by soil. Whether and how these two meristematic tissues have differential activation requirements for local nutrient, hormone, and environmental cues (e.g., light) remain enigmatic in photosynthetic plants. Here, we report that the activation of root and shoot apexes relies on distinct glucose and light signals. Glucose energy signaling is sufficient to activate target of rapamycin (TOR) kinase in root apexes. In contrast, both the glucose and light signals are required for TOR activation in shoot apexes. Strikingly, exogenously applied auxin is able to replace light to activate TOR in shoot apexes and promote true leaf development. A relatively low concentration of auxin in the shoot and high concentration of auxin in the root might be responsible for this distinctive light requirement in root and shoot apexes, because light is required to promote auxin biosynthesis in the shoot. Furthermore, we reveal that the small GTPase Rho-related protein 2 (ROP2) transduces light-auxin signal to activate TOR by direct interaction, which, in turn, promotes transcription factors E2Fa,b for activating cell cycle genes in shoot apexes. Consistently, constitutively activatedROP2plants stimulate TOR in the shoot apex and cause true leaf development even without light. Together, our findings establish a pivotal hub role of TOR signaling in integrating different environmental signals to regulate distinct developmental transition and growth in the shoot and root.
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, People's Republic of China.|University of Chinese Academy of Sciences, Shanghai 201602, People's Republic of China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Li
authors.affiliation: Horticultural Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fujian Province 350002, People's Republic of China.
authors.forename: Wenguo
authors.initials: W
authors.lastname: Cai
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, People's Republic of China.|University of Chinese Academy of Sciences, Shanghai 201602, People's Republic of China.
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, People's Republic of China.
authors.forename: Liwen
authors.initials: L
authors.lastname: Fu
authors.affiliation: Horticultural Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fujian Province 350002, People's Republic of China.
authors.forename: Zengyu
authors.initials: Z
authors.lastname: Liu
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, People's Republic of China.
authors.forename: Lin
authors.identifier: 0000-0003-4718-1286
authors.initials: L
authors.lastname: Xu
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, People's Republic of China.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Liu
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, People's Republic of China; yanxiong@sibs.ac.cn tdxu@sibs.ac.cn.
authors.forename: Tongda
authors.initials: T
authors.lastname: Xu
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, People's Republic of China; yanxiong@sibs.ac.cn tdxu@sibs.ac.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xiong
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics; D050684:E2F Transcription Factors / Q000235:genetics*; D004734:Energy Metabolism; D019204:GTP-Binding Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D005947:Glucose / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D008027:Light; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D010788:Photosynthesis / Q000235:genetics*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development; D020123:Sirolimus / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D050684:E2F Transcription Factors; D019204:GTP-Binding Proteins; D005947:Glucose; D007210:Indoleacetic Acids; D019869:Phosphatidylinositol 3-Kinases; D020123:Sirolimus; C496141:E2Fa protein, Arabidopsis; C512171:TOR protein, Arabidopsis; C499714:AT1G20090 protein, Arabidopsis
keywords: ROP2; TOR; auxin; glucose; light