Global transcriptome analysis identifies shade avoidance-related genes regulated by BBX24 in Arabidopsis thaliana

In seedlings, the induction of shade avoidance syndrome (SAS) involves a rapid up-regulation for known shade marker genes and subsequently activates an interacting network of various hormones that will eventually lead to cell elongation. We found that the B-box protein AtBBX24 have positive effects on the SAS (positive regulators). Global expression analysis of col and bbx24 seedlings reveals that a large number of genes involved in hormonal signaling pathways are positively regulated by BBX24 in response to simulated shade. The microarray experiment consisted in a factorial design comprising two genotypes (col and bbx24-1) and two light treatments (white light and simulated shade). RNA material was extracted from 7-day-old seedlings. Two replicates per treatment were performed using Affymetrix Arabidopsis ATH1 GeneChips. RNA was prepared, labeled and hybridized in accordance with the manufacturer’s instructions. Data were normalized and genes with ‘absent’ calls and a signal of <50 units in all replicate experiments were filtered out. Significantly differentially expressed genes were identified by performing profile analysis using Significance Analysis of Microarrays (SAM; Tusher et al., 2001).