title: GENERATIVE CELL SPECIFIC 1 is essential for angiosperm fertilization.
abstract: The double fertilization process in angiosperms is based on the delivery of a pair of sperm cells by the pollen tube (the male gametophyte), which elongates towards an embryo sac (the female gametophyte) enclosing an egg and a central cell. Several studies have described the mechanisms of gametophyte interaction, and also the fertilization process - from pollination to pollen tube acceptance. However, the mechanisms of gamete interaction are not fully understood. Cytological studies have shown that male gametes possess distinct cell-surface structures and genes specific to male gametes have been detected in cDNA libraries. Thus, studies of isolated gametes may offer clues to understanding the sperm-egg interaction. In this study, we identified a novel protein, designated GCS1 (GENERATIVE CELL SPECIFIC 1), using generative cells isolated from Lilium longiflorum pollen. GCS1 possesses a carboxy-terminal transmembrane domain, and homologues are present in various species, including non-angiosperms. Immunological assays indicate that GCS1 is accumulated during late gametogenesis and is localized on the plasma membrane of generative cells. In addition, Arabidopsis thaliana GCS1 mutant gametes fail to fuse, resulting in male sterility and suggesting that GCS1 is a critical fertilization factor in angiosperms.
authors.affiliation: Department of Life Science, College of Science, Rikkyo (St. Paul's) University, Nishiikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan. z2002377@tvr.rikkyo.ne.jp
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Mori
authors.forename: Haruko
authors.initials: H
authors.lastname: Kuroiwa
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Higashiyama
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Kuroiwa
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D005306:Fertilization; D020869:Gene Expression Profiling; D017343:Genes, Plant; D027762:Lilium; D019684:Magnoliopsida / Q000502:physiology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000378:metabolism / Q000502:physiology; D011058:Pollen / Q000166:cytology / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013234:Stem Cells / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; C548817:HAP2 protein, Arabidopsis; D010940:Plant Proteins