title: Arabidopsis SNARE protein SEC22 is essential for gametophyte development and maintenance of Golgi-stack integrity.
abstract: Membrane traffic contributes to plant growth and development. However, the functional significance of SNARE proteins involved in membrane fusion of the early secretory pathway has not been explored with respect to plant development. Here we analyze the Arabidopsis v-SNARE SEC22. Loss of SEC22 function impairs gametophyte development, as indicated by reciprocal crosses between wild-type plants and plants heterozygous for T-DNA insertions in the SEC22 gene. sec22 mutant pollen becomes abnormal during the bicellular stage, eventually giving rise to degenerated pollen grains. Most mutant embryo sacs fail to support embryogenesis and display unfused polar nuclei in their central cell. Immunolocalization by both light and electron microscopy revealed an association of mutant-complementing Myc-tagged SEC22 with the central and peripheral endoplasmic reticulum (ER). Ultrastructural analysis of developing sec22 mutant pollen demonstrated Golgi fragmentation and consumption. As a consequence, the plasma membrane-targeted syntaxin SYP124 was retained in the ER. Our results suggest that SEC22 plays an essential role in early secretory traffic between the ER and the Golgi.
authors.affiliation: Department of Developmental Genetics, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany.
authors.forename: Farid
authors.initials: F
authors.lastname: El-Kasmi
authors.forename: Tobias
authors.initials: T
authors.lastname: Pacher
authors.forename: Georg
authors.initials: G
authors.lastname: Strompen
authors.forename: York-Dieter
authors.initials: YD
authors.lastname: Stierhof
authors.forename: Lena M
authors.initials: LM
authors.lastname: Müller
authors.forename: Csaba
authors.initials: C
authors.lastname: Koncz
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mayer
authors.forename: Gerd
authors.initials: G
authors.lastname: Jürgens
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D004721:Endoplasmic Reticulum / Q000378:metabolism; D055993:Germ Cells, Plant / Q000254:growth & development* / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000648:ultrastructure; D016254:Mutagenesis, Insertional; D009154:Mutation; D018517:Plant Roots; D050683:R-SNARE Proteins / Q000032:analysis / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D050683:R-SNARE Proteins