Table 1.

Chemical structures, design strategies, and functions of ABA signaling modulators.

Category	Designation	Chemical Structure	Design Strategy	Function	References
ABA analogs	2′,3′-iso-PhABA		The introduction of a benzo ring at the 2′, 3′ position alters the molecular conformation.	Inhibitory effects on lettuce (Lactuca sativa) and Arabidopsis seed germination, wheat germination, and rice seedling elongation.	[175]
	(+)-BP2A		The diene on the side chain of ABA is replaced by a phenylacetic acid group.	ABA-like activity that inhibits the germination of tomato, lettuce, and rice seeds.	[177]
	9′,9′-difluoro-ABA		Chemical modifications to stabilize the cyclohexanone ring.	In radish seedlings and rice seedlings, the deactivation rate of ABA analogs is slower than that of ABA.	[180]
	(+)-tetralone ABA		Fusion of a cyclohexenone ring with a benzene ring.	More effectively complements the growth retardation of ABA-deficient Arabidopsis mutants than natural ABA.	[178]
ABA agonists	Quinabactin		Hydrogen bonds or halogen bonds form hydrophobic interactions with amino acid residues of the ABA receptor.	An inhibitory effect on seed germination.	[181]
	Opabactin		Structure-based design and molecular docking screening.	Inhibits seed germination and seedling growth in Arabidopsis and rice.	[182]
	JFA		Cell-free drug screening system for wheat.	Activation of PYR1 and PYL1 inhibits seed germination and cotyledon greening in seedlings.	[183]
ABA antagonists	(+)-PAT		Conformational constraint method.	Inhibits ABA-induced seed germination in Arabidopsis.	[184]
	AAT1		Chemical Genetics Screening	Broad-spectrum Arabidopsis ABA receptor antagonist.	[185]
	Aantabatin		Click chemistry for creating a derivative library.	Accelerates seed germination in Arabidopsis, tomato, and barley.	[186]