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 <b>A2</b> significantly promotes rice root growth, exhibiting effects more than twice those of the naphthylacetic acid (NAA). Additionally, <b>A2</b> enhances dry matter accumulation and increases chlorophyll content, thereby improving the disease resistance of rice. Preliminary mechanistic studies suggest that compound <b>A2</b> mimics auxin-like activity, similar to NAA, <b>A2</b> interacts with SER438 and PHE82, demonstrating strong binding affinity to the auxin receptor TIR1. Moreover, compound <b>A2</b> upregulates the auxin-responsive gene ARF, promoting cell elongation and accelerating lateral root development, leading to a larger root system in rice. Compound <b>A2</b> may have application potential as an auxin receptor agonist, providing a molecular basis for the design of root growth regulators.