Transcriptome for: MYB42 inhibits hypocotyl cell elongation by coordinating brassinosteroid homeostasis and signaling in Arabidopsis

The precise control of brassinosteroids (BRs) homeostasis and signaling is a prerequisite for hypocotyl cell elongation in plants. Little is known, however, of such regulators of BR homeostasis and signaling. Here, we have demonstrated that MYB42 negatively regulates hypocotyl elongation through partial inhibition of BRASSINAZOLE-RESISTANT 1 (BZR1) signaling and promotion of BR inactivation. Transgenic Arabidopsis plants repressing the expression of MYB42 and its paralog MYB85 (MYB85 RNAi;myb42) exhibited longer hypocotyls than wild-type (WT) plants in darkness, while MYB42 or MYB85 overexpression inhibits hypocotyl elongation. Hypocotyl length of MYB85 RNAi;myb42 plants can be resorted into WT level by MYB42 overexpression. MYB42 inhibits hypocotyl elongation by mediating BR signaling, because MYB42 expression is repressed with BR treatment and in the dominant BR mutant bzr1-1D, and mutation of both MYB42 and MYB85 enhances the dwarf phenotype of the BR receptor mutant bri1-5. BZR1 dir...