Opabactin is an agonist for abscisic acid (ABA) receptor, which regulates the water use of plants by mimicking the effects of ABA with an IC 50 of 7 nM. Opabactin inhibits the seed germination of Arabidopsis with an IC 50 of 62 nM. Opabactin induces anti-transpiration response in plant tissue, and improves crop drought tolerance.