Attenuated STM expression in drn and drnl mutants. (A-D) Patterns of pSTM::STM-Venus (green) in transverse sections through the vegetative shoot apex of 28-day-old wild-type Col-0 (A), drn-1 (B), drnl-2 (C) and drn-1 drnl-1 (D) plants. Plants are stained with propidium iodide (PI, red). The STM expression level is decreased in the mutants compared with wild type. (E-H) Patterns of pSTM::STM-Venus expression in P12 leaf axils in wild-type Col-0 (E), drn-1 (F), drnl-2 (G) and drn-1 drnl-1 (H). STM expression levels are lower in mature leaves in the mutants than in wild type. (I,J) STM-Venus expression levels in rev-6 in young (I) and mature (J) leaves. Arrows indicate leaf axils; numbers in A-J indicate leaf stages. (K) RT-qPCR analysis indicates that STM expression is significantly reduced in drn-1, drnl-2 and drn-1 drnl-1 mutant plants. Vegetative shoots with the leaves removed were analyzed. Error bars indicate s.d. *P<0.01 (Student's t-test). Scale bars: 100 μm.