Endogenous ABA in Growing Maize Roots: Light Effects.

The growth of intact maize (Zea mays L.) roots and the abscisic acid (ABA) content (measured by gas chromatography-mass spectrometry of the root tip were analyzed after a white-light treatment. The decrease of the elongation rate due to the illumination corresponded to a concomitant increase in the ABA found in the root. When selecting roots, on the basis of their growth rate, it was possible to show that the relation between growth and ABA content, previously reported in darkness was conserved after light treatments. Therefore, light decreased the root growth rate while it simultaneously increased the ABA content in the roots. This increase was higher than expected, demonstrating the complexity of the involvement of ABA on root growth.