Root architecture is crucial for plants to absorb water and nutrients. We previously reported edtl （edtlD） mutant with altered root architecture that contributes significantly to drought resistance. However, the underlying molecular mechanisms are not well understood. Here we report one of the mechanisms underlying EDT1/HDGll- conferred altered root architecture. Root transcriptome comparison between the wild type and edtlD revealed that the upregulated genes involved in jasmonate biosynthesis and signaling pathway were enriched in edtlD root, which were confirmed by quantitative RT-PCR. Further analysis showed that EDT1/HDG11, as a transcription factor, bound directly to the HD binding sites in the promoters of AOS, AOC3, OPR3, and OPCL1, which encode four key enzymes in JA biosynthesis. We found that the jasmonic acid level was significantly elevated in edtlD root compared with that in the wild type subsequently. In addition, more auxin accumulation was observed in thelateral root primordium of edtlD compared with that of wild type. Genetic analysis of edtlD opcl1 double mutant also showed that HDGll was partially dependent on JA in regulating LR formation. Taken together, overexpression of EDT1/HDGll increases JA level in the root of edtlD by directly upregulating the expressions of several genes encoding JA biosynthesis enzymes to activate auxin signaling and promote lateral root formation.
