Small molecule chemical scaffolds in plant growth regulators for the development of agrochemicals

Agrochemicals, especially plant growth regulators (PGRs), are extensively used to modulate endogenous phytohormone signals in small quantities, significantly influencing plant growth and development. Plant hormones typically exhibit diverse chemical structures, with common examples including indole rings, terpenoid frameworks, adenine motifs, cyclic lactones, cyclopentanones, and steroidal compounds, which are extensively employed in pesticides. This article explores the interactions and biological activities of small molecules on proteins, enzymes, and other reactive sites involved in the biosynthesis, metabolism, transport, and signal transduction pathways of various plant hormones. Additionally, it analyzes the structure-activity relationships (SARs) of pesticides incorporating these structural motifs to elucidate the relationship between active fragments, pharmacophores, and targets, highlighting the characteristics of potent small molecules and their derivatives. This comprehensive review aims to provide novel perspectives for the development and design of pesticides, offering valuable insights for researchers in the field.