Transcriptomic analysis of Hyperphyllin-treated Arabidopsis seedlings [ATH1 array]

ALTERED MERISTEM PROGRAM1 (AMP1) is a member of the M28 family of carboxypeptidases with a pivotal role in plant development and stress adaptation. Its most prominent mutant defect is a unique hypertrophic shoot phenotype combining a strongly increased organ formation rate with enhanced meristem size and the formation of ectopic meristem poles. However, so far the role of AMP1 in shoot development could not be assigned to a specific molecular pathway nor is its biochemical function resolved. We used a chemical genetic approach to identify the drug hyperphyllin (HP), which specifically mimics the shoot defects of amp1, including plastochron reduction and enlargement and multiplication of the shoot meristem. To further assess whether hyperphyllin acts in an AMP1-dependent manner we compared the transcriptonal responses of hyperphyllin-treated wild-type Arabidopsis seedlings with those of untreated amp1 mutant seedlings. Wild-type Arabidopsis seedlings were germinated and grown for 10 d in liquid medium in the presence of either DMSO (solvent) or 30 µM hyperphyllin, whereas amp1-13 seedlings were grown under the same conditions in medium containing only DMSO (solvent). For each treatment three biological replicates were used for RNA extraction and subsequent hybridization on Affymetrix microarrays.