title: Developmental and stress regulation of gene expression for a 9-cis-epoxycarotenoid dioxygenase, CstNCED, isolated from Crocus sativus stigmas.
abstract: Oxidative cleavage of cis-epoxycarotenoids by 9-cis-epoxycarotenoid dioxygenase (NCED) is the critical step in the regulation of abscisic acid (ABA) synthesis in higher plants. ABA has been associated with dormancy and flower senescence, while also regulating plant adaptive responses to various environmental stresses. An NCED gene, CstNCED, was cloned from Crocus sativus stigmas. The deduced amino acid sequence of the CstNCED protein shared high identity with other monocot NCEDs, and was closely related to the liliopsida enzymes. At the N-terminus of CstNCED a chloroplast transit peptide sequence is located. However, its expression in chloroplast-free tissues suggested localization in other plastid types. The relationship between expression of CstNCED and the endogenous ABA level was investigated in the stigma and corms, where it was developmentally regulated. The senescence of the unpollinated stigma is preceded by an increase in ABA levels and CstNCED expression. In corms, a correlation was observed between CstNCED expression and dormancy. Furthermore, CstNCED expression was correlated with the presence of zeaxanthin in the dormant corms. When detached C. sativus leaves and stigmas were water and salt stressed, increases in CstNCED mRNA were observed. The results provided evidence of the involvement of CstNCED in the regulation of ABA-associated processes such as flower senescence and corm dormancy in monocotyledonous saffron.
authors: Instituto Botánico, Departamento de Ciencia y Tecnología Agroforestal y Genética, Facultad de Farmacia, Universidad de Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain.
authors: Oussama
authors: O
authors: Ahrazem
authors: Angela
authors: A
authors: Rubio-Moraga
authors: Almudena
authors: A
authors: Trapero
authors: Lourdes
authors: L
authors: Gómez-Gómez
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000222:Adaptation, Physiological / Q000502:physiology*; D000595:Amino Acid Sequence; D002338:Carotenoids / Q000032:analysis / Q000378:metabolism; D027622:Crocus / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010802:Phylogeny; D057445:Plant Dormancy; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D012965:Sodium Chloride / Q000378:metabolism; D013312:Stress, Physiological / Q000502:physiology; D013997:Time Factors; D014867:Water / Q000378:metabolism; D024341:Xanthophylls / Q000032:analysis / Q000378:metabolism; D065146:Zeaxanthins
chemical_list: D010937:Plant Growth Regulators; D010940:Plant Proteins; D024341:Xanthophylls; D065146:Zeaxanthins; D014867:Water; D002338:Carotenoids; D012965:Sodium Chloride; D000040:Abscisic Acid; D049308:Dioxygenases; C109043:9-cis-epoxy-carotenoid dioxygenase