Induction of jasmonic acid biosynthetic genes inhibits Arabidopsis growth in response to low boron

The essential micronutrient boron (B) has key roles in cell wall integrity and B deficiency inhibits plant growth. The role of jasmonic acid (JA) in plant growth inhibition under B deficiency remains unclear. Here, we report that low B elevates JA biosynthesis in Arabidopsis thaliana by inducing the expression of JA biosynthesis genes. Treatment with JA inhibited plant growth and, a JA biosynthesis inhibitor enhanced plant growth, indicating that the JA induced by B deficiency affects plant growth. Furthermore, examination of the JA signaling mutants jasmonate resistant1, coronatine insensitive1‐2, and myc2 showed that JA signaling negatively regulates plant growth under B deficiency. We identified a low‐B responsive transcription factor, ERF018, and used yeast one‐hybrid assays and transient activation assays in Nicotiana benthamiana leaf cells to demonstrate that ERF018 activates the expression of JA biosynthesis genes. ERF018 overexpression (OE) lines displayed stunted growth and up‐regulation of JA biosynthesis genes under normal B conditions, compared to Col‐0 and the difference between ERF018 OE lines and Col‐0 diminished under low B. These results suggest that ERF018 enhances JA biosynthesis and thus negatively regulates plant growth. Taken together, our results highlight the importance of JA in the effect of low B on plant growth. The boron‐responsive ethylene response factor ERF018 activates jasmonic acid (JA) biosynthetic genes under boron deficiency. The resulting increase in JA triggers JA signaling via production of JA‐isoleucine catalyzed by JASMONATE‐RESISTANT1 to negatively regulate primary root growth.