CELL WALL SYNTHESIS AND CELL ELONGATION IN OAT COLEOPTILE TISSUE

Ray , Peter M. (U. Michigan, Ann Arbor.) Cell wall synthesis and cell elongation in oat coleoptile tissue. Amer. Jour. Bot. 49(9): 928–939. Illus. 1962.—Cell wall synthesis in oat coleoptile cylinders tends to run parallel with but not usually proportional to cell elongation both under promotion by auxin and sugar and under inhibition by supraoptimal auxin or sugar, or by a variety of other inhibitors. Inhibitors of elongation fall into 2 classes with respect to their effects on wall synthesis: (1) those which inhibit the 2 processes approximately equally (galactose, mannose, mannitol, azide, iodoacetate, dinitrophenol, low temperature, supraoptimal auxin) and (2) those which inhibit elongation percentagewise much more strongly than wall synthesis, so that as complete inhibition of elongation is approached, substantial wall synthesis continues (Ca^{+ +}, fluoride, arsenite, mercurials). When coleoptile cylinders elongate in the absence of sugar, the cell walls appear to become markedly thinner, and in some experiments negligible increase in total wall material apparently occurs. However, the amount of α-cellulose does rise. Increase in cell wall material occurs during elongation of cylinders at 2 C. The results are interpreted as indicating that during elongation the bulk of new cell wall material is added by apposition, but a certain proportion of the new material is probably introduced within the existing wall structure and induces its expansion.