Recent studies of the brassinosteroid-deficient mutants have revealed that brassinosteroid plays essential roles to control plant growth and development, such as cell elongation, division and photomorphogenesis. However, its regulatory mechanisms and signal transduction pathway are still under unclear. We used DNA microarray (Gene Chip, Affymetfix) to analyze BR-regulated genes comprehensively. BL inhibited the expression of the gene for phytochrome-.interacting factor 3, indicating that BRs modulate the light signaling pathway rather than function as signaling molecules downstream of light. After a lag period, BL also increased the expression of early auxin-inducible genes, suggesting that BR signaling overlaps with the auxin signaling pathway to controlcellular processes.
