title: Chromate induces adventitious root formation via auxin signalling and SOLITARY-ROOT/IAA14 gene function in Arabidopsis thaliana.
abstract: Morphological root plasticity optimizes nutrient and water uptake by plants and is a promising target to improve tolerance to metal toxicity. Exposure to sublethal chromate [Cr(VI)] concentrations inhibits root growth, decreases photosynthesis and compromises plant development and productivity. Despite the increasing environmental problem that Cr(VI) represents, to date, the Cr tolerance mechanisms of plants are not well understood, and it remains to be investigated whether root architecture remodelling is important for plant adaptation to Cr(VI) stress. In this report, we analysed the growth response of Arabidopsis thaliana seedlings to concentrations of Cr(VI) that strongly repress primary and lateral root growth. Interestingly, adventitious roots started developing, branched and allowed seedlings to grow under highly growth-repressing Cr(VI) concentrations. Cr(VI) negatively regulates auxin transport and response gene expression in the primary root tip, as evidenced by decreased expression of auxin-related reporters DR5::GFP, DR5::uidA and PIN1::PIN1::GFP, and then, another auxin maximum is established at the site of adventitious root initiation that drives adventitious root organogenesis. Both primary root growth inhibition and adventitious root formation induced by high Cr(VI) levels are blocked by a gain-of-function mutation in the SOLITARY-ROOT/IAA14 gene of Arabidopsis. These data provide evidence that suggests a critical role for auxin transport and signalling via IAA14/SLR1 in the developmental program linking Cr(VI) to root architecture remodelling.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edifico B3, Ciudad Universitaria, C. P. 58030, Morelia, Michoacán, México, jbucio@umich.mx.
authors.forename: José
authors.initials: J
authors.lastname: López-Bucio
authors.forename: Randy
authors.initials: R
authors.lastname: Ortiz-Castro
authors.forename: León Francisco
authors.initials: LF
authors.lastname: Ruíz-Herrera
authors.forename: Consuelo Vargas
authors.initials: CV
authors.lastname: Juárez
authors.forename: Fátima
authors.initials: F
authors.lastname: Hernández-Madrigal
authors.forename: Yazmín
authors.initials: Y
authors.lastname: Carreón-Abud
authors.forename: Miguel
authors.initials: M
authors.lastname: Martínez-Trujillo
mesh_terms: D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002840:Chromates / Q000633:toxicity*; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000502:physiology*; D017680:Potassium Compounds / Q000633:toxicity*
chemical_list: D029681:Arabidopsis Proteins; D002840:Chromates; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D010937:Plant Growth Regulators; D017680:Potassium Compounds; C116363:PIN1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis; C027373:potassium chromate(VI)