title: 14-3-3 isoforms and pattern formation during barley microspore embryogenesis.
abstract: The members of the 14-3-3 isoform family have been shown to be developmentally regulated during animal embryogenesis, where they take part in cell differentiation processes. 14-3-3 isoform-specific expression patterns were studied in plant embryogenic processes, using barley (Hordeum vulgare L.) microspore embryogenesis as a model system. After embryogenesis induction by stress, microspores with enlarged morphology showed higher viability than non-enlarged ones. Following microspore culture, cell division was only observed among the enlarged microspores. Western blot and immunolocalization of three barley 14-3-3 isoforms, 14-3-3A, 14-3-3B and 14-3-3C were carried out using isoform-specific antibodies. The level of 14-3-3C protein was higher in enlarged microspores than in non-enlarged ones. A processed form of 14-3-3A was associated with the death pathway of the non-enlarged microspores. In the early embryogenesis stage, 14-3-3 subcellular localization differed among dividing and non-dividing microspores and the microspore-derived multicellular structures showed a polarized expression pattern of 14-3-3C and a higher 14-3-3A signal in epidermis primordia. In the late embryogenesis stage, 14-3-3C was specifically expressed underneath the L(1) layer of the shoot apical meristem and in the scutellum of embryo-like structures (ELSs). 14-3-3C was also expressed in the scutellum and underneath the L(1) layer of the shoot apical meristem of 21 d after pollination (DAP) zygotic embryos. These results reveal that 14-3-3A processing and 14-3-3C isoform tissue-specific expression are closely related to cell fate and initiation of specific cell type differentiation, providing a new insight into the study of 14-3-3 proteins in plant embryogenesis.
authors.affiliation: Center for Phytotechnology LU/TNO, TNO Department of Applied Plant Sciences, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands. maraschin@rulbim.leidenuniv.nl
authors.forename: Simone de F
authors.initials: Sde F
authors.lastname: Maraschin
authors.forename: Gerda E M
authors.initials: GE
authors.lastname: Lamers
authors.forename: B Sylvia
authors.initials: BS
authors.lastname: de Pater
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.forename: Mei
authors.initials: M
authors.lastname: Wang
mesh_terms: D048948:14-3-3 Proteins; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology; D005298:Fertility / Q000502:physiology; D001467:Hordeum / Q000196:embryology / Q000378:metabolism*; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism; D020033:Protein Isoforms / Q000096:biosynthesis; D012639:Seeds / Q000254:growth & development / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis*
chemical_list: D048948:14-3-3 Proteins; D020033:Protein Isoforms; D014446:Tyrosine 3-Monooxygenase