Rapid Effects of IAA on Cell Surface Proteins from Intact Carrot Suspension Culture Cells

Abstract

ABSTRACESuspension cultures of carrot (DaIcus carrota L.) which had an absolute requirement for exogenously supplied auxin were grown in medium containing indoleacetic acid (IAA) as the sole auxin source. Putative cell surface proteins were extracted from the intact cells. Resup-ply of IAA to cultures partially depleted of auxin resulted in rapidly increased activities of three enzyme activities subsequently extracted. Two of the enzyme activities which increased, peroxidase and pectinesterase, have been implicated in the literature as important to cell wail development, stucture, and growth. The other enzyme activity which was increased, IAA oxidase, may be involved in the degradation of IAA In rivo. Polypeptides in the extracts were found to increase equaly as rapidly as the enzymes in response to IAA as determined with sodium dodecyl sulfate-polyacrylamide electrophoretic gels stained with silver. It is not known whether the changes in enzyme and polypeptide levels in the protein extracts were due to auxin effects on protein synthesis, transport, or extractability.The effects of auxin on cell enlargement and tissue elongation have been the most extensively studied actions of this plant growth substance. It is clear that cell wall growth and extension are the events which limit and allow this enlargement and elongation. While cell wall acidification appears to be very important in the early stages of rapid auxin-induced growth (13), there is increasing evidence that DNA transcription and mRNA translation may play equally important roles in auxin induced growth (10,12,25,29

Carrot somatic embryogenesis depends on the phytohormone-controlled presence of correctly glycosylated extracellular proteins

“…Another group of lytic enzymes that can affect cell wall structure are peroxidases, of which several specific isozymes appear well corelated with tobacco organogenesis (Kay and Basile 1987). Recently there is a growing interest in the role of auxin-regulated cell wall associated proteins (O'Neill and Scott 1987). Despite the fact that plant cell walls contain, in addition to complex polysaccharides, hundreds of different proteins, glycoproteins (Roberts et al 1985), and proteoglycans (McNeil et al 1984), only the cell wall glycoprotein extensin has been cloned and studied in detail (Stafstrom and Staehelin 1987;Tierney and Varner 1987).…”

Heterogeneity and Cell Type-Specific Localization of a Cell Wall Glycoprotein from Carrot Suspension Cells

“…To (21). Immunoblotting showed that the medium EPl proteins of 31/32 and 52/54 kD are indeed present in the cell wall (Fig.…”

Monoclonal antibody against a cell wall marker protein for embryogenic potential of Dactylis glomerata L. suspension cultures

“…This method allows for the isolation of ionically bound cell wall proteins from intact cells without contaminating cytoplasmic proteins (O'Neill and Scott 1987). Immunoblotting showed that EP48 was indeed present in the cell wall of embryogenic microclusters (lane 2 in Fig.…”

“…After overnight at 4°C, the precipitate was collected by centrifugation (12,000 g at 4°C for 30 min), vacuum-dried and stored at À70°C or dissolved in water for immediate use (De Vries et al 1988). The cell wall proteins were isolated from sedimented living cells according to O'Neill and Scott (1987). After washing twice with fresh SH-0 medium, the cells were incubated in 0.1 mM CaCl 2 on ice for 25 min, centrifuged and the supernatant was passed through a Millipore 0.22 lm filter.…”