Effects of cordycepin on IAA- and fusicoccin-stimulated cell enlargement, proton extrusion and potassium uptake in maize coleoptiles

In maize (Zea mays F, XL 640 A, DEKALB) coleoptiles, cordycepin (3′-deoxyadenosine) is very active in preventing the cell elongation. H⁺ extrusion and K⁺ uptake induced by IAA and, to a much lesser degree, the same phenomena induced by fusicoccin (FC). Cordycepin, while depressing uridine incorporation into RNA, does not decrease the ATP level or significantly influence the pyruvate level and leucine incorporation into proteins in this material. These results support the hypothesis that one or more proteins. whose synthesis is dependent upon short half-life mRNAs, are essential for a full response to IAA. while this requirement is only partial in FC-stimulation of growth. They also confirm the view that auxin- or FC-induced activation of H⁺/K⁺ exchange plays an important role in mediating the effects of these compounds on cell enlargement.