The Effect of Indoleacetic Acid on Cell Wall Extensibility inAvenaColeoptiles

Abstract

The extensibility of cell walls in segments of living Avena coleoptiles has been determined after treatment with IAA by the use of a microextensometer. It has been demonstrated that IAA has an effect both on the plastic and elastic extensibility, which is more marked if the segments are allowed to grow, except at temperatures nearing 0° C. The auxin-induced increase in extensibility is therefore not a direct effect on the wall and metabolic factors must be involved. The results are interpreted, along cunent lines of thought, as indicating effects on the linkage between protopectin or hemicellulose chains themselves and between these and the microfibrillar network of cellulose. The bearing of these interpretations on the normal growth process in cell walls is briefly discussed.