title: ACR4, a putative receptor kinase gene of Arabidopsis thaliana, that is expressed in the outer cell layers of embryos and plants, is involved in proper embryogenesis.
abstract: The surfaces of higher plants are characterized by epidermis, which usually consists of a single layer of cells. The epidermis is derived from the outer cell layer of the embryo or protoderm, which arises as a result of periclinal cell division. After seed germination, most of the epidermal cells of the aerial parts of plants are derived from the outer cell layer of the shoot apical meristem (the L1 layer). Thus, knowledge of how the protoderm and/or L1 layer is established is fundamental to understanding the morphogenesis of higher plants. Here, we report the isolation of a gene encoding an Arabidopsis homologue (ACR4) of the maize putative receptor kinase CRINKLY4 (CR4), which is involved in epidermal differentiation. The domain organization of the predicted amino acid sequence of ACR4 is essentially identical to that of CR4. ACR4-GFP fusion protein localized to the cell surface when expressed in tobacco cell (BY-2) culture. ACR4 transcripts were detected in all the organs of the Arabidopsis plant. In developing embryos and shoot apices, ACR4 transcripts accumulated in protoderm and epidermis at relatively higher levels than in the inner tissues. Over-expression of antisense ACR4 in Arabidopsis plants resulted in malformation of embryos to varying degrees. These results suggest that ACR4 is, at a minimum, involved in the normal morphogenesis of embryos, most likely through properly differentiating protoderm cells.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku 464-8602 Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Masaru
authors.initials: M
authors.lastname: Watanabe
authors.forename: Daisuke
authors.initials: D
authors.lastname: Watanabe
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Chiyoko
authors.initials: C
authors.lastname: Machida
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Machida
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D019441:Plant Epidermis / Q000201:enzymology / Q000235:genetics*; D018547:Plant Stems / Q000201:enzymology / Q000235:genetics*; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D012639:Seeds / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D003313:Zea mays / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D020794:Receptor Protein-Tyrosine Kinases; C462019:ACR4 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases