title: De-regulation of abscisic acid contents causes abnormal endosperm development in the barley mutant seg8.
abstract: Grain development of the maternal effect shrunken endosperm mutant seg8 was analysed by comprehensive molecular, biochemical and histological methods. The most obvious finding was de-regulation of ABA levels, which were lower compared to wild-type during the pre-storage phase but higher during the transition from cell division/differentiation to accumulation of storage products. Ploidy levels and ABA amounts were inversely correlated in the developing endosperms of both mutant and wild-type, suggesting an influence of ABA on cell-cycle regulation. The low ABA levels found in seg8 grains between anthesis and beginning endosperm cellularization may result from a gene dosage effect in the syncytial endosperm that causes impaired transfer of ABA synthesized in vegetative tissues into filial grain parts. Increased ABA levels during the transition phase are accompanied by higher chlorophyll and carotenoid/xanthophyll contents. The data suggest a disturbed ABA-releasing biosynthetic pathway. This is indicated by up-regulation of expression of the geranylgeranyl reductase (GGR) gene, which may be induced by ABA deficiency during the pre-storage phase. Abnormal cellularization/differentiation of the developing seg8 endosperm and reduced accumulation of starch are phenotypic characteristics that reflect these disturbances. The present study did not reveal the primary gene defect causing the seg8 phenotype, but presents new insights into the maternal/filial relationships regulating barley endosperm development.
authors.affiliation: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstraße 3, D-06466 Gatersleben, Germany.
authors.forename: Nese
authors.initials: N
authors.lastname: Sreenivasulu
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Radchuk
authors.forename: Ali
authors.initials: A
authors.lastname: Alawady
authors.forename: Ljudmilla
authors.initials: L
authors.lastname: Borisjuk
authors.forename: Diana
authors.initials: D
authors.lastname: Weier
authors.forename: Nicole
authors.initials: N
authors.lastname: Staroske
authors.forename: Jörg
authors.initials: J
authors.lastname: Fuchs
authors.forename: Otto
authors.initials: O
authors.lastname: Miersch
authors.forename: Marc
authors.initials: M
authors.lastname: Strickert
authors.forename: Björn
authors.initials: B
authors.lastname: Usadel
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wobus
authors.forename: Bernhard
authors.initials: B
authors.lastname: Grimm
authors.forename: Hans
authors.initials: H
authors.lastname: Weber
authors.forename: Winfriede
authors.initials: W
authors.lastname: Weschke
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D002454:Cell Differentiation; D056625:Endosperm / Q000166:cytology / Q000254:growth & development*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D010788:Photosynthesis; D011003:Ploidies; D015398:Signal Transduction; D013213:Starch / Q000096:biosynthesis; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D024341:Xanthophylls; D000040:Abscisic Acid; D013213:Starch