Enrichment of vitronectin‐ and fibronectin‐like proteins in NaCl‐adapted plant cells and evidence for their involvement in plasma membrane–cell wall adhesion

Abstract

SummaryCells of tobacco adapted to grow in high concentrations of NaCl develop tight zones of adhesion between the plasma membrane and cell wall, revealed by concave plasmolysis in osmotic solutions. Unadapted cells exhibit mostly convex plasmolysis and exhibit little or no adhesive character. Wall-less protoplasts isolated from the adapted cells retain the complementary adhesive character and adhere tightly to each other, whereas protoplasts from unadapted cells do not. The hexapeptide gly-arg-gly-aspser-pro, in which the arg-gly-asp represents the integrin-binding domain of several animal extracellular matrix proteins, specifically blocks adhesion of the protoplasts. A control hexapeptide, gly-arg-gly-glu-ser-pro, is ineffective in blocking adhesion. Tobacco proteins immunologically related to human vitronectin were found in cell walls and membranes of unadapted and NaCIadapted cells, but the total extractable vitronectin-like protein was enriched in the adapted cells. Tobacco proteins immunologically related to human fibronectin were found in membranes and cell walls of NaCIadapted cells but not in those from unadapted cells. Our observations indicate that plant cells possess cell-matrix adhesion complexes similar to animal cells, and these adhesion complexes accumulate in growth-limited cells adapted to saline stress.

Osmosensitive Changes of Carbohydrate Metabolism in Response to Cellulose Biosynthesis Inhibition

“…Bulging epidermal cells in CBI-treated seedlings have been described before and would support this hypothesis (Hamann et al, 2009;Tsang et al, 2011). Previous work by other research groups has provided additional evidence for the importance of plant cell walls in the regulation of turgor pressure and response to drought/osmotic stress (Zhu et al, 1993(Zhu et al, , 2010Chen et al, 2005). To summarize, the results presented here suggest that a turgor pressure-sensitive mechanism could regulate carbohydrate metabolism and raise the question of whether CBI treatment could generate a hypoosmotic stress situation (since hyperosmotic stress treatments have been shown to suppress the CBI-induced changes in transcript and enhanced starch levels).…”

Differential cytoplasm-plasma membrane-cell wall adhesion patterns and their relationships to hyphal tip growth and organelle motility

“…Wang et al 1994;Gens et al 1996) were indicated in various walled cells by crossreactions with antibodies made against animal adhesion molecules. The involvement of integrins was also supported by sensitivity of adhesions to RGD peptides (Schindler et al 1989, Klotz and Smith 1991, Wayne et al 1992, Zhu et al 1993, Henry et al 1996, Ryu et al 1997, which are known to disrupt focal contacts in animal cells. However, the peptides were not always functional (Holdaway et al 1995), and cloning of the genes for these proteins has either not been successful Carpita 1993, Reuzeau andPont-Lezica 1995), or resulted in completely unrelated genes (Zhu et al 1994, J. Wang et al 1996.…”

“…The involvement of integrins was also supported by sensitivity of adhesions to RGD peptides (Schindler et al 1989, Klotz and Smith 1991, Wayne et al 1992, Zhu et al 1993, Henry et al 1996, Ryu et al 1997, which are known to disrupt focal contacts in animal cells. However, the peptides were not always functional (Holdaway et al 1995), and cloning of the genes for these proteins has either not been successful Carpita 1993, Reuzeau andPont-Lezica 1995), or resulted in completely unrelated genes (Zhu et al 1994, J. Wang et al 1996. Plant-specific proteins such as hydroxyproline-rich and arabinogalactan glycoproteins may also be involved , Knox 1995, Reuzeau and Pont-Lezica 1995.…”

“…1989, Quatrano etal. 1991, Kaminskyj and Heath 1995, Gens et al 1996, Gale et al 1996, and vitronectin and fibronectin-like proteins in the cell wall (Sanders et al 1991;Wagner et al 1992;Zhu et al 1993Zhu et al , 1994C. Wang et al 1994;Gens et al 1996) were indicated in various walled cells by crossreactions with antibodies made against animal adhesion molecules.…”

High molecular mass glycoproteins associated with the siliceous scales and bristles of Mallomonas splendens (Synurophyceae) may be involved in cell surface development and maintenance

“…The glycoproteins labelled by MsS.H9 may be part of a complex that anchors the scales and bristles but still allows for their coordinated movement during cell growth and cytokinesis. Interestingly, immunological homologs to fibronectin, vitronectin and integrin have recently been identified in higher plants (Schindler et al 1989;Sanders et al 1991;Zhu et al 1993;Wang et al 1994) and in the embryo of the brown alga Fucus (Wagner et al 1992). The exact functions of these extracellular glycoproteins have not been fully identified; however, like their animal counterparts, these plant and algal polypeptides do appear to function in cell adhesion.…”