Figure 1.

Dexamethasone-Inducible HD-ZIPIII Activity Leads to Leaf Adaxialization and Upregulation of a Family of Small Leucine Zipper Proteins.

(A) Diagram of the dexamethasone-inducible REV fusion protein. Transcription is driven by the widely expressed CaMV35S promoter. GR, glucocorticoid binding domain; HD, homeodomain; LZ, leucine zipper domain; START, domain with similarity to steroid binding domain; PAS, similar to PAS domain; MTS*, mutant microRNA target sequence.

(B) and (C) Two views of a seedling treated briefly (5 min) with dexamethasone (50 μM) 1 week after germination.

(B) Two leaves developed a trumpet shape with adaxial characters on the outside of the trumpet bell.

(C) Leaves that developed subsequently developed with normal ad/abaxial polarity. rlf, radial leaf; lf, normal leaf.

(D) Real-time RT-PCR shows increase in transcript levels of four ZPR genes following dexamethasone induction of 35S:GR-REVd transgenic plants. Seedlings were treated with dexamethasone for 2 h before tissue was harvested. Bars indicate se for at least three measurements (technical replicates). The experiment was repeated three times with similar results (data not shown).

(E) Real-time RT-PCR detection of ZPR3 mRNA in shoots from three self progeny (biological replicates) with strong abaxialized phenotypes from parents of the genotype phv; phb; rev/+. Bars indicate se for at least three measurements (technical replicates).

(F) Real-time RT-PCR of phb-d mutants (shoots from three pooled homozygotes) and phv-d mutants (shoots from two individuals [biological replicates]). Bars indicate se for at least three measurements (technical replicates).