Auxin-Induced Downregulates to Inhibit Lateral Root Formation in Hance.

Lateral root (LR) formation promotes plant resistance, whereas high-level ethylene induced by abiotic stress will inhibit LR emergence. Considering that local auxin accumulation is a precondition for LR generation, auxin-induced genes inhibiting ethylene synthesis may thus be important for LR development. Here, we found that auxin response factor 4 () in Hance could be induced by auxin. The overexpression of decreased the LR number and reduced the vessel diameters. Meanwhile, the auxin distribution mode was altered in the root tips and expression was also decreased in the overexpressed lines compared with the wild-type (WT) plants. The overexpression of could reduce ethylene synthesis, and thus, the repression of ethylene production decreased the LR number of WT and reduced expression in the roots. Furthermore, the quantitative real-time PCR, chromatin immunoprecipitation sequencing, yeast one-hybrid, and dual-luciferase assay results showed that could bind the promoter of 1-aminocyclopropane-1-carboxylate oxidase 4 (), associated with ethylene biosynthesis, and could downregulate its expression. Therefore, we concluded that induced by auxin can inhibit ethylene biosynthesis by repressing expression, and this process may affect auxin transport to delay LR development.