The Role of Wall-Bound Hydroxyproline-Rich Protein in Cell Extension

Abstract

The influence of G.A. and LA.A. on the hydroxyproline content of cell walls was examined with reference to the concept of wall-bound protein as a cross-linking agent regulating wall extensibility. It appeared that the hydroxyproline-rich protein content of cell walls pf elongating cells from the stems of two pea varieties, Alaska and Rondo, differed remarkably. Inaccordance with Lamport's hypothesis, the dwarf variety (Rondo) had a much higher hydroxyproline content than the standard variety (Alaska). When G.A. was applied to the top of the slow growing dwarf variety, the growth rate increased until comparable to the standard variety and the hydroxyproline content of the cell walls decreased somewhat. However, no linear relationship between growth stimulation and decreased hydroxyproline content existed.Experiments performed with excised elongating pea stem segments, grown in a culture solution containing phosphate buffer, showed that the hydroxyproline content of the cell walls increased considerably during an incubation time of 24 hours. IAA strongly inhibited this increase while stimulating elongation. However, a solution containing IAA and sugar caused the greatest elongation but also the greatest formation of hydroxyproline. It was concluded that cell extension and the hydroxyproline content of cell walls are not necessarily inversely correlated.

Hydroxyproline‐induced Changes in Form, Apical Development, and Cell Wall Protein in the Liverwort Plagiochila Arctica

“…The essence of their hypothesis is that there is an inverse relationship between the amount of wall-bound hyp-protein and the capacity for cells to elongate. This hypothesis has been supported by Bailey and Kauss (1974), Fujii and Shimokoriyama (1976), Monro et al (1974), Ridge and Osborne (1970), Sadava et al (1973), Sadava andVaughan et al (1974), but has been questioned by Jotterand-Dolivo and Pilet (1975), Klis (1976), Lang (1976), and Winter et al (1971). Similarly, an inverse relationship between the accumulation of hyp-protein in cell walls and cell proliferation has been noted by Roberts and Northcote (1972) and by Steward et al (1974).…”