Induction of abscisic acid in excised maize roots by osmotic and salt stress

Abstract

Moderate water stresses in the range 0 to 0.6 MPa applied with polyethylene glycol (PEG) 6000 to excised roots of Zea mays L. var. LG 11, induced increases of up to four-fold in the amount of free and bound abscisic acid (ABA) detected in the root after a 12 h period of xylem exudation. The ABA concentration in xylem exudate collected after a 2 h PEG-induced water stress to excised roots also increased by up to four-fold. Salt stresses, induced with NaCl solutions, resulted in similar increases in the free and bound ABA concentrations in root tissue and in the ABA concentration of the xylem exudate. The ABA concentrations in both root tissue and xylem exudate were highest 4 h after removal of the stress and then declined over the next 8 h. These results are interpreted as support for the concept that root-produced ABA may have a role in the fine control of the plant’s water balance.