EARLY EFFECTS OF PLANT-CELL WALL FRAGMENTS ON PLANT-CELL GROWTH

Growth effects induced by base-solubilized cell wall fragments and by indolacetic acid (IAA) were investigated for both mung bean hypocotyls and wheat coleoptiles. Significant effects were noted: (a), wall-frag ment solution concentrations above 10(-5) mg ml-1 notably decreased th e growth rate, whereas high auxin concentrations had no inhibitory eff ects, (b) low concentrations (less-than-or-equal-to 10(-6) mg ml-1) of these fragments enhanced the growth rate but were less effective than auxin and the kinetics were different; the lag time being longer with wall fragments, (c) IAA induced a strong enhancement of all cell wall extensibility parameters, whereas wall fragments increased only plast icity and creep but not the elasticity, (d) at pH 5.8, an important bu t transient decrease in the pH of the incubation medium was induced by the wall fragments, whereas with auxin no significant H+ efflux could be noted. The biologically active components were most probably oligo saccharides. These data underline that active oligosaccharides and aux in stimulate growth via different mechanisms.