1′-OH of ABA and its analogs is a crucial functional group correspondence to seed germination and development of plants.

• The key role for bioactivity retention of the 1'-OH group of ABA was clarified. • 1'-OMe analogs showed selective bioactivity to different physiological processes. • PYL5 is a selective receptor closely responded to plant growth process. • The hydrogen bond network between PYL5 and 1'-OMe analogs was destructed. Abscisic acid (ABA) is an essential phytohormone involved in many physiological processes, including plant growth inhibition and abiotic stress responses. Its signal transduction pathway is mediated by a genetically redundant family of ABA receptors (PYLs). In this work, 1′-O methyl ethers of ABA and its analogs were designed for chemically probing PYLs. The results suggested that 1′-OH is a crucial functional group correspondence to seed germination and development of plants, but has little relation on the stomatal movement and the response to drought stress regulated by ABA and its analogs. The methylation of 1′-OH significantly reduced their binding ability to monomer receptor PYL5 and slightly enhanced their binding to dimer receptor PYL2. The decrease of inhibition activities of 2a-2c was most probably assigned to the decrease of binding affinity with PYL5, which was due to the destruction of hydrogen bond network. This indicated that PYL5 was a selective receptor closely responded to plant growth process. [ABSTRACT FROM AUTHOR]