Tomato (Solanum lycopersicum) is an important horticultural crop worldwide. UV-B signaling is extensively investigated in the model plant Arabidopsis thaliana, however, much less is explored in crops. We investigate UV-B signaling in tomato in our laboratory. We generated a series of tomato mutants including uvr8, cop1, cop1-homolog, spa3 and hy5 with CRISPR/CAS9 approach. With these major mutant lines, we compared UV-B signaling in Arabidopsis and tomato. We found both commonanity and specificity of UV-B signaling in these two plant species. I will present our recent data of UV-B signaling in tomato plant development and metabolism.