Plant Regulation Functions of Novel Phthalimide Compounds Based on AtPYL2.

Novel agents contain the structure of phthalimide, which has antibacterial, insecticidal, and herbicidal activities. Recently, studies reported that these compounds can bind to plant hormone receptors and play important regulatory roles. In this study, the functions of agents were studied with and assays. The abscisic acid (ABA) receptor pyrabactin resistant-like 2 (PYL2) protein in was expressed, purified, and crystallized; the analysis results of the crystal structure showed three AtPYL2 subunits in each asymmetric unit. The affinity of compounds - to the AtPYL2 protein was tested by microscale thermophoresis (MST) and then verified by isothermal titration calorimetry (ITC). Furthermore, the binding pockets were found using molecular docking to verify the target relationships. Relevant assays for seed germination and a root growth assay were conducted, with the plant samples being treated with target compounds. The results show that the compounds , , and target AtPYL2 and that the dissociation constants for binding by MST were 3.59, 3.54, and 3.97 μmol/L, respectively, among them, and the molecular docking results showed that compounds , , and formed hydrophobic interactions with amino acid residues through hydrogen or halogen bonding. This highlights their potential as an ABA receptor protein agonist. On the other hand, , compounds , , and had different inhibitory effects on seed germination, with compound inhibiting the root growth of and compound affecting root growth. In conclusion, these compounds could regulate plant growth and could be further developed as new plant-regulating agents.