The cell wall hydroxyproline-rich glycoprotein RSH is essential for normal embryo development in Arabidopsis.
Although a large number of embryo mutants have been studied, mostly at the morphological level, the critical molecular and cellular events responsible for embryogenesis are unknown. Here, we report that using an enhancer-trap embryo mutant of Arabidopsis, we identified a gene, ROOT-SHOOT-HYPOCOTYL-DEFECTIVE (RSH), that is essential for the correct positioning of the cell plate during cytokinesis in cells of the developing embryo. We traced the earliest point of influence of RSH to the first asymmetrical division of the zygote. Homozygous rsh embryos were defective morphologically, had irregular cell shape and size, and germinated to form agravitropic-defective seedlings incapable of further development. The RSH gene encodes a Hyp-rich glycoprotein-type cell wall protein. RSH localized to the cell wall throughout the embryo and to a few well-defined postembryonic sites. Although several lines of evidence from previous work suggest that the cell wall is involved in development, the protein(s) involved remained elusive.
Hall
Qi
Q
Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003-4505, USA.
Cannon
Maura C
MC
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division / Q000235:genetics; D048429:Cell Size; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D002874:Chromosome Mapping; D003598:Cytoskeletal Proteins; D020869:Gene Expression Profiling; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins; D012639:Seeds / Q000254:growth & development*; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D003598:Cytoskeletal Proteins; D006023:Glycoproteins; D010940:Plant Proteins; C463466:RSH protein, Arabidopsis; C005488:extensin protein, plant