Synthesis, Biological Activity and Mechanism of Action of Pyridine-Containing Arylthiourea Derivatives

A well-developed root system is a key factor in improving crop quality, as it can absorb water, nourish and resist stress. A series of arylthiourea derivatives were synthesized and their biological activities were evaluated in this study. The results indicate that compound A2 significantly promotes rice root growth, exhibiting effects more than twice those of the naphthylacetic acid (NAA). Additionally, A2 enhances dry matter accumulation and increases chlorophyll content, thereby improving the disease resistance of rice. Preliminary mechanistic studies suggest that compound A2 mimics auxin-like activity, similar to NAA, A2 interacts with SER438 and PHE82, demonstrating strong binding affinity to the auxin receptor TIR1. Moreover, compound A2 upregulates the auxin-responsive gene ARF, promoting cell elongation and accelerating lateral root development, leading to a larger root system in rice. Compound A2 may have application potential as an auxin receptor agonist, providing a molecular basis for the design of root growth regulators.