The Requirement for Calcium and Boron in Auxin Transport

Abstract

The requirement for Ca in auxin transport was first observed in sunflower hypocotyl tissue with Ca deficiency induced by chelation of tissue Ca. The longer the hypocotyl segments were incubated in EDTA solution, the more Ca was lost to the medium and the greater was the inhibition of auxin transport [4]. These results were confirmed with sunflower seedlings grown in Ca-deficient Hoagland solution [3]. Auxin transport was found to be linear with the log concentration of Ca in the root medium from 10⁻⁶ to 10⁻³ M. The most significant finding in these experiments, regardless of the method used to induce Ca deficiency, was that the inhibition of auxin transport can be reversed to the control, nondeficient level by the simple incubation of the hypocotyl segments in Ca solution, prior to the measurement of auxin transport [3, 4].