Inhibition of Auxin-Induced Cell Elongation of Maize Coleoptiles by Antibodies Specific for Cell Wall Glucanases

Abstract

Polyclonal antibodies were raised in rabbits in response to the administration of purified exo- and endoglucanases extracted from cell walls of maize (Zea mays L. B37 x Mo17) coleoptiles. Since the antibodies formed specific conjugates when challenged with the glucanase antigens in immunoblot assays they were employed to evaluate the participation of glucanases in tissue growth. Indole-3-acetic acid induced cell elongation of abraded coleoptile segments was inhibited when the antibodies were supplied as a short term pretreatment (25-200 microgram/milliliter of serum protein). The extent of inhibition of IAA induced cell elongation was additive when endo- and exoglucanase antibodies were applied together. The results suggest that both enzymes have a role in mediating IAA-induced cell elongation. Pretreatment with exo- and endoglucanases antibodies also inhibited IAA induced degradation of noncellulosic beta-d-glucans and the increased level of cellulosic polymers in maize coleoptiles. Antibodies also inhibited the expression of the autohydrolytic degradation of glucans in isolated cell walls. The extent of inhibition was dependent on the antibody concentration applied. The results support the contention that enzymatic processes mediated by exo- and endoglucanases are responsible for cell wall autolytic reactions and that these reactions are linked to the mechanism for expressing auxin induced cell elongation in maize coleoptiles.