Effect of the tetrapeptide RGDS on somatic embryogenesis in Daucus carota

Abstract

The present work examines the requirement for RGD-binding sites, such as those in the plasma membrane protein integrin during somatic embryogenesis in carrot (Daucus carota L. cv. Scarlet nantes). It is possible to assay for this requirement by competitively inhibiting binding of the site to the natural RGD-containing ligand by adding an excess of synthetic RGDS. We found that treatment of carrot callus cultures with RGDS (2.7 mM) inhibited the development of a normal shoot pole in carrot somatic embryos. The structures that formed contained separate zones of highly cytoplasmic and vacuolate cells and no evidence of embryonic organization, although occasionally a root-like structure was observed. If the aspartic acid residue in the peptide was replaced by a chemically similar amino acid (glutamic acid), the resultant somatic embryos were indistinguishable from those developing in untreated cultures. These effects are similar to those reported in animal systems where the protein receptor involved has been identified as integrin. Our results are thus consistent with the conclusion that a binding site for a motif similar to the integrin-binding site in a variety of animal extracellular matrix proteins exists in plants and appears to be important in somatic embryo development in carrot.

Identification and characterization of a matrix metalloproteinase (Pta1-MMP) expressed during Loblolly pine (Pinus taeda) seed development, germination completion, and early seedling establishment

“…These include plant proteins similar to vitronectin (Sanders et al 1991), Wbronectin (Pellenc et al 2004), and integrin (Katembe et al 1997). Interestingly, RGDS tetrapeptides, which are known to bind to integrins, can modify somatic embryo development when applied to carrot cultures (Blackman et al 2001), implicating integrinlike molecules in the regulation of embryo development. Whether the above types of proteins represent plant MMP substrates remains to be addressed.…”

PLASMOLYSIS, HECHTIAN STRAND FORMATION, AND LOCALIZED MEMBRANE‐WALL ADHESIONS IN THE DESMID, CLOSTERIUM ACEROSUM (CHLOROPHYTA)1

“…Application of exogenous RGD peptides can be used to block or significantly alter integrin-based events. In plants, experiments using RGD peptides have been important in demonstrating integrin participation in such activities as sunflower embryoid formation, maize callus development, pollen tube growth, adaptation to salt stress, adhesion of the PM-CW, gravisensing in charophyte algae, zygote adhesion, and development of fucoid algae and somatic development in carrot (Wayne et al 1992, Henry et al 1996, Kiba et al 1998, Barthou et al 1999, Laboure et al 1999, Sun et al 2000, Blackman et al 2001). Canut et al (1998) also demonstrated that RGD peptides cause the loss of Hechtian strands during onion cell plasmolysis.…”

RGD-Dependent Mechanotransduction of Suspension Cultured Taxus Cell in Response to Shear Stress

“…The Arabidopsis genome database shows that plant seem to lack a homologue of animal integrin. However, the recent demonstration of high affinity RGD binding sites in the plasma membrane of Arabidopsis (23,27) and effects of RGD peptide on the physiological processes of plant cells (25)(26)(27)(29)(30)(31)(32)(33) suggest that RGD-mediated protein-protein interactions actually exist in plant cells. Lack of a homologue of animal integrin shown by the Arabidopsis genome database and the facts of effects of RGD peptide on plant physiological processes suggest that although the molecules involved in plasma membrane-ECM interactions in plants and animals may differ in their exact structures, plants may possess functionally analogous adhesion proteins.…”