IR of SR protein genes found in the top 1,000 light-regulated IR events. Quantitative RT-PCR analysis of IR level in samples grown under the dark (0-h light), 1-h, and 4-h of red (red-colored bars) and blue (blue-colored bar) light are shown. IR level of SR protein genes were tested in triplicate with primer sets designed for IR isoforms, total transcripts of the corresponding genes, and PpACT2 (see Additional file 7). Intron number (intNo) of the gene counted from 5′ of the genome is labeled after the gene name. Bc, constant blue light.