title: Flavonols Mediate Root Phototropism and Growth through Regulation of Proliferation-to-Differentiation Transition.
abstract: Roots normally grow in darkness, but they may be exposed to light. After perceiving light, roots bend to escape from light (root light avoidance) and reduce their growth. How root light avoidance responses are regulated is not well understood. Here, we show that illumination induces the accumulation of flavonols in Arabidopsis thaliana roots. During root illumination, flavonols rapidly accumulate at the side closer to light in the transition zone. This accumulation promotes asymmetrical cell elongation and causes differential growth between the two sides, leading to root bending. Furthermore, roots illuminated for a long period of time accumulate high levels of flavonols. This high flavonol content decreases both auxin signaling and PLETHORA gradient as well as superoxide radical content, resulting in reduction of cell proliferation. In addition, cytokinin and hydrogen peroxide, which promote root differentiation, induce flavonol accumulation in the root transition zone. As an outcome of prolonged light exposure and flavonol accumulation, root growth is reduced and a different root developmental zonation is established. Finally, we observed that these differentiation-related pathways are required for root light avoidance. We propose that flavonols function as positional signals, integrating hormonal and reactive oxygen species pathways to regulate root growth direction and rate in response to light.
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain Departamento de Genética, Facultad de Biología, Universidad Complutense de Madrid, Madrid 28040, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Silva-Navas
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain pozo@inia.es miguelangel.moreno@upm.es.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Moreno-Risueno
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.
authors.forename: Concepción
authors.initials: C
authors.lastname: Manzano
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.
authors.forename: Bárbara
authors.initials: B
authors.lastname: Téllez-Robledo
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Navarro-Neila
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.
authors.forename: Víctor
authors.initials: V
authors.lastname: Carrasco
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain.
authors.forename: Stephan
authors.initials: S
authors.lastname: Pollmann
authors.affiliation: Departamento de Genética, Facultad de Biología, Universidad Complutense de Madrid, Madrid 28040, Spain.
authors.forename: F Javier
authors.identifier: 0000-0002-9921-8960
authors.initials: FJ
authors.lastname: Gallego
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Pozuelo de Alarcón, 28223 Madrid, Spain pozo@inia.es miguelangel.moreno@upm.es.
authors.forename: Juan C
authors.identifier: 0000-0002-4113-457X
authors.initials: JC
authors.lastname: Del Pozo
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology / Q000528:radiation effects; D044948:Flavonols / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008027:Light; D018524:Phototropism / Q000235:genetics / Q000502:physiology; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology* / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D015398:Signal Transduction / Q000502:physiology / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D044948:Flavonols; D010937:Plant Growth Regulators