Dynamics of limiting cell wall porosity in plant suspension cultures

Abstract

Changes in the limiting porosity of cell walls, i.e. the size limit for permeation of neutral molecules through the wall, were studied in several higher-plant cell-suspension cultures. For this purpose, samples of biomass ®xed at dierent cultivation times were investigated using a method based on size-exclusion chromatography of polydisperse dextrans before and after equilibration with the extracted cell clusters. In suspension cultures of Chenopodium album L., Dioscorea deltoidea Wall. and Medicago sativa L., the mean size limit (MSL; critical Stokes' radius for exclusion of neutral polymers from half of the intracellular space) was found to vary between 2.4 and 3.8 nm. It decreased signi®cantly during transition from the growth phase to the stationary phase. In the case of the C. album culture this change was found to be irrespective of whether sucrose in the medium was completely depleted at the end of the growth phase or not. The MSL was kept constant for long periods of the stationary phase if cell viability was maintained by repeated sucrose supplement. In a suspension strain of Triticum aestivum L., the MSL of cell wall permeation was comparatively small (1.75 nm) and remained constant during all cultivation phases. Relations between limiting porosity and cell wall growth, loss of pectic compounds to the medium, crosslinking activities and cell wall stiening are discussed.Abbreviations: DPS = dextran probing solution; LCP = limiting cell wall porosity; MSL = mean size limit

Conditioning of the culture medium by suspension cells and formation of somatic proembryo in Araucaria angustifolia (coniferae)

“…Enhancement of membrane permeability and cell wall porosity may also contribute to increases in protein release (Payne et al, 1991;Titel et al, 1997). A cell suspension of Chenopodium album showed changes in wall porosity, which was high at the beginning of the intensive growth phase and declined during the transition to the stationary phase (Titel et al, 1997).…”

“…Liquid cultures are often considered to be the most appropriate approach for economic propagation (Preil, 1991;Tautorus et al, 1994). Embryogenic masses culturing in liquid medium facilitates the appraisal of cellular organization (Durzan and Chalupa, 1976), the analysis of carbohydrate metabolism (Lulsdorf et al, 1992), the use of osmotic treatments to promote embryo maturation (Roberts, 1991), the release of extracellular proteins (Mäes et al, 1997) and the study of the chemical composition and physical properties of the cell walls during growth (Titel et al, 1997). It is also a method for rapid clonal multiplication which is less labor-intensive when compared to multiplication on solid media.…”

The Pore Size of Non-Graminaceous Plant Cell Walls Is Rapidly Decreased by Borate Ester Cross-Linking of the Pectic Polysaccharide Rhamnogalacturonan II

“…Nevertheless, using the same method, differences can be demonstrated in the wall pore size of different plant tissues and plant cells in different physiological states (Carpita et al, 1979;Carpita, 1982;Woehlecke and Ehwald 1995;Titel et al, 1997). The method used to determine wall pore size in this study has also been used to show that the walls of C. album cells have a higher pore size in the growth phase than in the stationary phase (Titel et al, 1997), and that the wall pore size of growing B-deficient cells is higher than that of cells growing in the presence of 100 m B (Fleischer et al, 1998).…”

“…The cells were rehydrated and the excess water removed by gentle suction. The cells were then incubated for 30 min in a polydisperse dextran solution and the size dependence of dextran partitioning was determined by size-exclusion chromatography (SEC) as previously described (Woehlecke and Ehwald, 1995;Titel et al, 1997;Fleischer et al, 1998).…”

The changes in cell wall architecture during lignification of bamboo, Phyllostachys aurea Carr.

“…13.1 nm, which is similar to those in the suspension-cultured cells of A. cepa and P. alba. Titel et al (1998aTitel et al ( , 1998b) measured pore size by using dextran permeation as an index of pore size, and compared the size among various suspension-cultured cells. The pores in suspension-cultured cells of Triticum aestivum (wheat) were smaller than in those of two dicot species (Medicago sativa and Dioscorea deltoidea).…”