Analysis of gene expression controlled by light and brassinosteroids. Arabidopsis thaliana

Plant photomorphogenesis and skotomorphogenesis depend on interplay of various plant hormones. Brassinosteroids (BRs) play crucial roles during hypocotyl establishment both in the light and darkness. Arabidopsis brassinosteroid insensitive1 (bri1-5) is a partial loss-of-function mutant, and the short-hypocotyl phenotype of bri1-5 is greatly suppressed by a long-hypocotyl mutant phytochrome B (pbyB-77) at the double mutant for the two in the light conditions to display additive phenotypes of both. To identify the genes responsible for this genetic interaction, we employed microarray analysis with the RNAs prepared from wild type, bri1-5, phyB-77, and bri1-5 phyB-77 double mutant. Microarray analysis supported the notion that PHYB acts upstream of BRs. Overall design: Total RNAs were isolated from four different genotypes: wild type, bri1-5, gul2-1/phyB-77, bri1-5 gul2-1 double mutant, and the RNAs were subjected to microarray analysis using Affymetrix GenChip arrays. Three biological replicates for each genotype resulted in 12 experiments.