title: Osmoconditioning prevents the onset of microtubular cytoskeleton and activation of cell cycle and is detrimental for germination of Jatropha curcas L. seeds.
abstract: Jatropha curcas is an oilseed crop renowned for its tolerance to a diverse range of environmental stresses. In Brazil, this species is grown in semiarid regions where crop establishment requires a better understanding of the mechanisms underlying appropriate seed, seedling and plant behaviour under water restriction conditions. In this context, the objective of this study was to investigate the physiological and cytological profiles of J. curcas seeds in response to imbibition in water (control) and in polyethylene glycol solution (osmoticum). Seed germinability and reactivation of cell cycle events were assessed by means of different germination parameters and immunohistochemical detection of tubulin and microtubules, i.e. tubulin accumulation and microtubular cytoskeleton configurations in water imbibed seeds (control) and in seeds imbibed in the osmoticum. Immunohistochemical analysis revealed increasing accumulation of tubulin and appearance of microtubular cytoskeleton in seed embryo radicles imbibed in water from 48 h onwards. Mitotic microtubules were only visible in seeds imbibed in water, after radicle protrusion, as an indication of cell cycle reactivation and cell proliferation, with subsequent root development. Imbibition in osmoticum prevented accumulation of microtubules, i.e. activation of cell cycle, therefore germination could not be resumed. Osmoconditioned seeds were able to survive re-drying and could resume germination after re-imbibition in water, however, with lower germination performance, possibly due to acquisition of secondary dormancy. This study provides important insights into understanding of the physiological aspects of J. curcas seed germination in response to water restriction conditions.
authors.affiliation: Laboratório de Bioquímica, Biotecnologia e Bioprodutos, Departamento de Bioquímica e Biofísica, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador-Ba, Brazil.
authors.forename: C D
authors.initials: CD
authors.lastname: de Brito
authors.affiliation: Laboratório de Bioquímica, Biotecnologia e Bioprodutos, Departamento de Bioquímica e Biofísica, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador-Ba, Brazil.
authors.forename: M B
authors.initials: MB
authors.lastname: Loureiro
authors.affiliation: Laboratório de Bioquímica, Biotecnologia e Bioprodutos, Departamento de Bioquímica e Biofísica, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador-Ba, Brazil.|Departamento de Química Orgânica, Instituto de Química, Universidade Federal da Bahia, Salvador-Ba, Brazil.
authors.forename: P R
authors.initials: PR
authors.lastname: Ribeiro
authors.affiliation: Laboratório de Bioquímica, Biotecnologia e Bioprodutos, Departamento de Bioquímica e Biofísica, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador-Ba, Brazil.
authors.forename: P C T
authors.initials: PC
authors.lastname: Vasconcelos
authors.affiliation: Laboratório de Bioquímica, Biotecnologia e Bioprodutos, Departamento de Bioquímica e Biofísica, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador-Ba, Brazil.
authors.forename: L G
authors.initials: LG
authors.lastname: Fernandez
authors.affiliation: Laboratório de Bioquímica, Biotecnologia e Bioprodutos, Departamento de Bioquímica e Biofísica, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador-Ba, Brazil. renatodelmondez@ufba.br.
authors.forename: R D
authors.identifier: http://orcid.org/0000-0002-4166-1417
authors.initials: RD
authors.lastname: de Castro
mesh_terms: D002453:Cell Cycle; D003599:Cytoskeleton / Q000378:metabolism*; D018525:Germination; D031286:Jatropha / Q000166:cytology / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D009997:Osmotic Pressure; D036226:Seedlings / Q000166:cytology / Q000502:physiology; D012639:Seeds / Q000166:cytology / Q000502:physiology; D013312:Stress, Physiological; D014404:Tubulin / Q000378:metabolism; D014867:Water / Q000502:physiology
chemical_list: D014404:Tubulin; D014867:Water
keywords: Cell cycle; Jatropha sp.; germination; microtubular cytoskeleton; oilseed; osmotic stress