title: Abscisic acid and transpiration rate are involved in the response to boron toxicity in Arabidopsis plants.
abstract: Boron (B) is an essential microelement for vascular plant development, but its toxicity is a major problem affecting crop yields in arid and semi-arid areas of the world. In the literature, several genes involved in abscisic acid (ABA) signalling and responses are upregulated in Arabidopsis roots after treatment with excess B. It is known that the AtNCED3 gene, which encodes a crucial enzyme for ABA biosynthesis, plays a key role in the plant response to drought stress. In this study, root AtNCED3 expression and shoot ABA content were rapidly increased in wild-type plants upon B-toxicity treatment. The Arabidopsis ABA-deficient nced3-2 mutant had higher transpiration rate, stomatal conductance and accumulated more B in their shoots than wild-type plants, facts that were associated with the lower levels of ABA in this mutant. However, in wild-type plants, B toxicity caused a significant reduction in stomatal conductance, resulting in a decreased transpiration rate. This response could be a mechanism to limit the transport of excess B from the roots to the leaves under B toxicity. In agreement with the higher transpiration rate of the nced3-2 mutant, this genotype showed an increased leaf B concentration and damage upon exposure to 5 mM B. Under B toxicity, ABA application decreased B accumulation in wild-type and nced3-2 plants. In summary, this work shows that excess B applied to the roots leads to rapid changes in AtNCED3 expression and gas exchange parameters that would contribute to restrain the B entry into the leaves, this effect being mediated by ABA.
authors.affiliation: Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, 41013, Sevilla, Spain.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Macho-Rivero
authors.affiliation: Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, 41013, Sevilla, Spain.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Camacho-Cristóbal
authors.affiliation: Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, 41013, Sevilla, Spain.
authors.forename: María Begoña
authors.initials: MB
authors.lastname: Herrera-Rodríguez
authors.affiliation: Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, 08028, Barcelona, Spain.
authors.forename: Maren
authors.initials: M
authors.lastname: Müller
authors.affiliation: Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, 08028, Barcelona, Spain.
authors.forename: Sergi
authors.initials: S
authors.lastname: Munné-Bosch
authors.affiliation: Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, 41013, Sevilla, Spain.
authors.forename: Agustín
authors.initials: A
authors.lastname: González-Fontes
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001895:Boron / Q000633:toxicity*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D005838:Genotype; D009154:Mutation / Q000235:genetics; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D000040:Abscisic Acid; D001895:Boron