A Chemical Genetics Method to Uncover Small Molecules for Dissecting the Mechanism of ABA Responses in Arabidopsis Seed Germination

Functional redundancy widely exists in genes encoding receptors and signaling components of plant hormones, particularly the stress hormone abscisic acid (ABA). The redundancy hinders the use of conventional genetic approach to dissecting molecular mechanisms for ABA signal perception and transduction. Chemical genetics approach, in which bioactive small molecules are used to perturb the function of gene products encoded by functionally redundant genes, provides an excellent alternative strategy to investigate ABA signaling. This approach led to the discovery of ABA receptor family, PYR/PYL/RCAR (Zhao et al., Nat Chem Biol 3:716–721, 2007; Park et al., Science 324:1068–1071, 2009). A forward chemical genetics screen uncovered an ABA agonist, pyrabactin, which provides a critical small-molecule probe to the identification of the ABA receptor family and the dissection of its downstream signaling.