Interactions Between the Transcription Factor BOL/DRNL/ESR2 and the Jasmonate Pathway.

BOL/DRNL/ESR2, an AP2/ERF transcription factor, regulates early organ development in Arabidopsis (Arabidopsis thaliana). Its loss of function causes flower organ defects, while its overexpression induces green callus formation in roots without the addition of hormones. Jasmonates, plant hormones known as major players in stress responses, also regulate some aspects of organ development (e.g., stamen development and plant and organ growth). Here, we studied the interaction between BOL and the JA pathway. We found that exogenous application of methyl jasmonate (MeJA) partially rescued the stamen phenotypes in bol-cr mutants, linking BOL and JA-mediated stamen development. Moreover, MeJA treatments in wild-type plants partially mimicked some bol-D mutant phenotypes like reduced rosette and root size, while JA inhibition restored wild-type leaf curvature, suggesting an alteration in JA homeostasis in the gain-of-function mutant. BOL overexpression caused increased JA levels, whereas bol loss-of-function plants had reduced levels. Furthermore, inducible BOL activity led to downregulation of a JA-responsive marker. Finally, JA biosynthesis inhibition affected BOL-induced root callus formation and led to an expansion of the BOL expression domain in roots. Our findings indicate that BOL modulates parts of the JA pathway and that feedback from the JA pathway appears to affect expression of the transcription factor.