D’orenone Blocks Polarized Tip Growth Of Root Hairs By Interfering With The PIN2-Mediated Auxin Transport Network In The Root Apex

The study demonstrated that D’orenone, a C18 ketone, significantly inhibited the polarized tip growth of root hairs in Arabidopsis thaliana by interfering with the PIN2-mediated auxin transport network in the root apex. At nanomolar concentrations, D’orenone rapidly blocked root hair growth without affecting primary root growth, although it increased lateral root density at higher concentrations. D’orenone increased the abundance and expanded the expression domain of the PIN2 protein, enhancing auxin signaling and transport specifically in the transition zone. The inhibitory effect on root hair growth was reversible with exogenous auxin, indicating that D’orenone's action was closely related to auxin levels and signaling pathways. The study provided insights into the molecular mechanisms of root hair development and introduced D’orenone as a novel tool for dissecting auxin-related signaling networks. Additionally, D’orenone rescued the agravitropic phenotype in the agr1-2 mutant line but had no effect on the pin2 null mutant line (eir1-4), confirming PIN2 specificity. The findings suggested that D’orenone might act as a hormone-like signaling molecule, providing insights into auxin signaling and transport in root development.