Basipetal Auxin transport in lettuce and its possible involvement in acropetal calcium transport and incidence of tipburn

Abstract

Abstract The relationship between polar basipetal indoleacetic acid (IAA) transport and acropetal calcium transport and the incidence of tipburn was studied in lettuce (Lactuca sativa). In lettuce plants treated with triiodo‐benzoic acid (TIBA), an auxin transport inhibitor, incidence of tipburn was increased. In young leaves, calcium concentrations were lowered by TIBA treatment, while the concentrations of potassium and magnesium were unaffected. In short‐term experiments with isolated shoot tips of lettuce it could be demonstrated in TIBA‐treated plants that both basipetal transport of IAA and acropetal transport of calcium ( Ca) to the growing tip were inhibited. The results support the view that a system for polar basipetal auxin transport exists in low transpiring vegetative tissue, which is associated with an acropetal calcium transport independent of transpiration.