title: Effect of overexpression of citrus 9-cis-epoxycarotenoid dioxygenase 3 (CsNCED3) on the physiological response to drought stress in transgenic tobacco.
abstract: 9-cis-epoxycarotenoid dioxygenase (NCED) encodes a key enzyme in abscisic acid (ABA) biosynthesis. Little is known regarding the regulation of stress response by NCEDs at physiological levels. In the present study, we generated transgenic tobacco overexpressing an NCED3 ortholog from citrus (CsNCED3) and investigated its relevance in the regulation of drought stress tolerance. Wild-type (WT) and transgenic plants were grown under greenhouse conditions and subjected to drought stress for 10 days. Leaf predawn water potential (Ψwleaf), stomatal conductance (gs), net photosynthetic rate (A), transpiration rate (E), instantaneous (A/E) and intrinsic (A/gs) water use efficiency (WUE), and in situ hydrogen peroxide (H2O2) and abscisic acid (ABA) production were determined in leaves of irrigated and drought-stressed plants. The Ψwleafdecreased throughout the drought stress period in both WT and transgenic plants, but was restored after re-watering. No significant differences were observed in gs between WT and transgenic plants under normal conditions. However, the transgenic plants showed a decreased (P ≤ 0.01) gs on the 4th day of drought stress, which remained lower (P ≤ 0.001) than the WT until the end of the drought stress. The A and E levels in the transgenic plants were similar to those in WT; therefore, they exhibited increased A/gs under drought conditions. No significant differences in A, E, and gs values were observed between the WT and transgenic plants after re-watering. The transgenic plants had lower H2O2and higher ABA than the WT under drought conditions. Our results support the involvement of CsNCED3 in drought avoidance.
authors.affiliation: Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
authors.forename: A M
authors.initials: AM
authors.lastname: Pedrosa
authors.affiliation: Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
authors.forename: L C
authors.initials: LC
authors.lastname: Cidade
authors.affiliation: Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
authors.forename: C P S
authors.initials: CP
authors.lastname: Martins
authors.affiliation: Laboratório de Biologia Celular de Plantas, Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: A F
authors.initials: AF
authors.lastname: Macedo
authors.affiliation: Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
authors.forename: D M
authors.initials: DM
authors.lastname: Neves
authors.affiliation: Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
authors.forename: F P
authors.initials: FP
authors.lastname: Gomes
authors.affiliation: Laboratório de Biologia Celular de Plantas, Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: E I S
authors.initials: EI
authors.lastname: Floh
authors.affiliation: Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil marciogc.costa@gmail.com.
authors.forename: M G C
authors.initials: MG
authors.lastname: Costa
mesh_terms: D000040:Abscisic Acid / Q000096:biosynthesis; D000222:Adaptation, Physiological; D002957:Citrus / Q000201:enzymology / Q000235:genetics; D049308:Dioxygenases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D055864:Droughts; D018515:Plant Leaves / Q000201:enzymology / Q000378:metabolism; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D013312:Stress, Physiological; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D010940:Plant Proteins; D000040:Abscisic Acid; D049308:Dioxygenases; C109043:9-cis-epoxy-carotenoid dioxygenase