DELLA targets in proliferating leaf tissue

Transcriptome changes 1h or 4h following DELLA stabilisation in microdissected fully proliferating Arabidopsis leaves 35S::gai-GR plants (Claeys et al., 2012) were grown on meshes overlaying 1/2 MS medium for 9 days, and were then transferred to plates containing 5 µM dexamethasone or DMSO (mock). Samples were obtained from three independent experiments and from multiple plates within the experiment. Whole seedlings were harvested rapidly in an excess of RNAlater® solution (Ambion) and, after overnight storage at 4°C, the third leaf was dissected from 128 plants under a binocular microscope on a cooling plate with precision microscissors. Dissected leaves were transferred to a new tube, frozen in liquid nitrogen, and ground with a Retsch machine and 3-mm metal balls. RNA was extracted with TriZol (Invitrogen) and further purified with the RNeasy Mini Kit (Qiagen). DNA digestion was done on columns with RNase-free DNase I (Roche). One µg of pure RNA samples were hybridized to Affymetrix ATH1 arrays at the VIB Microarray Facility (Leuven, Belgium).