Synthesis, Translocation, and Biological Activity of an Artificial Glucosinolate with a Fipronil-Based Aglycone as a Vectorizing Agrochemical

The conversion of nonsystemic pesticides into systemic agents can enhance their efficacy, with plant transporters representing a promising strategy. Glucosinolate transporters (GTR1/GTR2) mediate glucosinolate uptake and transport but remain unexplored for pesticide uptake. In this study, we synthesized an artificial glucosinolate (FIP-GSL) with fipronil as the substituent group. Xenopus oocyte assays showed that GTR1/GTR2 mediated FIP-GSL uptake in a proton-dependent manner. Molecular docking revealed conserved salt-bridge interactions between the sulfate group of FIP-GSL and key residues (Lys79/Arg196 in GTR1; Lys61/Arg180 in GTR2), which were essential for proton-coupled transport. In Arabidopsis, FIP-GSL exhibited phloem-mediated translocation in wild-type plants, but this translocation was reduced in the gtr1, gtr2, and gtr1gtr2 mutants. Biological assays revealed that although the direct activity of FIP-GSL was lower than that of fipronil, its systemic efficacy was significantly enhanced. Moreover, FIP-GSL displayed substantially reduced toxicity to bees. These findings demonstrate that exploiting GTR1 and GTR2 to enhance pesticide uptake and translocation could offer a promising strategy for improving the systemic activity of agrochemicals.