Genome-wide analysis of the BR response in msg2 and axr2

Although a wide range of interactions between BRs and auxin have been recognized, knowledge about the direct molecular mechanism of interaction between them in specific physiological processes is very limited. In this study we found that auxin resisitent mutant msg2/iaa19 and arf7 were also resisitant to the BR effect on morphogenensis of dark-grown Arabidosis seedlings. Moreover, BR signaling transcription factor BZR1 can directly bind to promoter regions of IAA19 and ARF7. Microarray analysis revealed that a number of gene transcripts showed reduced BR response in msg2 and the control mutant axr2, suggesting the crucial role of IAA19 in mediating BR effects. Taken together, our results suggested that BRs regulate morphogenesis of dark-grown seedling by employing auxin signaling components IAA19 and ARF7. Four-day-old seedlings of WT, msg2 and axr2 grown on MS medium in the absence or presence of 24-eBL (100 nM) were used. Total RNA extraction and ATH1 microarray(Affymetrix) experiments were performend according to manufacturer’s protocols. Raw data were normalized by MAS 5.0 algorithm, Gene Spring Software 11.0. All experiments including two biological replicates and the Pearson correlation coefficient was analyzed to check the replicate quality.