Jasmonic Acid Modulates Xylem Development by Controlling Expression of .

Jasmonic acid (JA) modulates plant development, growth, and responses to stress. Previously, we showed that in , JA promotes the formation of extra xylem in roots, and mutant plants unable to express () and formed extra xylem in the absence of exogenous JA. Those results suggested that JA modulates root xylem development by controlling PIN-mediated polar auxin transport. Consistent with this, treatment with an auxin transport inhibitor induced extra xylem formation. Here, we characterized the expression of and in JA-treated plants. expression was not altered in response to JA; by contrast, expression was reduced by JA, which suggested that is involved in JA-mediated xylem development. Indeed, overexpressing suppressed the formation of extra xylem in response to JA. Based on these results, we propose that JA mediates xylem development by controlling polar auxin transport with PIN7 critically involved in this process.