Phenotypic analysis of Arabidopsis mutants: gibberellin/abscisic acid/paclobutrazol hormone response

INTRODUCTIONSeed germination requires breaking the dormancy that is maintained by abscisic acid (ABA) and involves the activation of gibberellin (GA) biosynthesis and signaling. Mutants with low germination rates may be defective in GA biosynthesis and/or signaling and often require exogenous GAs for efficient germination. Conversely, mutants with either increased GA signaling or reduced signaling by the GA antagonist ABA are resistant to GA-biosynthesis inhibitors or ABA, respectively. Mutants with enhanced GA signaling or decreased ABA content are also more resistant to inhibition of germination by Paclobutrazol (PAC), a GA biosynthesis inhibitor. This protocol describes the measurement of the germination rate of Arabidopsis seeds in the presence of GA, ABA, or PAC.