Physicochemical quantification of abscisic acid levels in plant tissues with an added internal standard by ultra-performance liquid chromatography

The phytohormone abscisic acid (ABA) is critical for a range of plant responses to the environment, most importantly in closing the stomata of seed plants during drought (Mittelheuser and Van Steveninck 1969; Brodribb <i>et al.</i> 2014). The high precision quantification of this hormone by physicochemical methods is a relatively simple process, essential for studies that aim to investigate the role or action of this hormone in plants. Outlined here is a method for the extraction, purification and quantification of ABA levels in plant tissues. This method involves methanolic extraction of ABA from homogenised tissue. Purification of ABA is then undertaken by a simple etheric partitioning method. A focus is placed on determining ABA levels in leaves; however this method is suitable for all tissue types, including plant solutes such as xylem sap, seeds (both dry and green) and large samples of tissue such as root systems.