The blue light signaling inhibitor 3-bromo-7-nitroindazole affects gene translation at the initial reception of blue light in young seedlings.

Initial light reception after germination is a dramatic life event when a seedling starts proper morphogenesis. Blue light contains a range of light wavelengths that plants can perceive. A previous report suggested that the chemical compound 3-bromo-7-nitroindazole (3B7N) inhibits blue light-mediated suppression of hypocotyl elongation by physically interacting with the blue light receptor Cryptochrome 1 (CRY1). We previously examined changes of genome-wide gene expression in seedlings germinated in the dark and then exposed to blue light by RNA-seq and Ribo-seq analyses. The expression of ribosome-related genes was translationally upregulated in response to the initial blue light exposure, depending on signals from both the nucleus and chloroplasts. Here, we re-analyzed our previous data and examined the effect of 3B7N treatment on changes in gene expression upon blue light exposure. The results showed that 3B7N negatively affected translation of ribosome-related genes and, interestingly, the effects were similar to not only those in mutants but also plants under suppression of photosynthesis. We propose an apparent crosstalk between chloroplast function and blue light signaling.