Plant responses to changing environmental stress: Cyclobutyl pyrimidine dimer repair in soybean leaves

We have determined the capacity of soybean seedlings to repair DNA damage by UV doses that do not produce apparent injury in the plants. They remove cyclobutane pyrimidine dimers by both excision and photoreactivation. The rates and relative contributions of these repair processes were determined as a function of initial level of cyclobutyl pyrimidine dimers. Photoreactivation was detected in seedlings at all initial dimer levels. Although excision was not observed at the lowest dimer frequencies, at higher initial dimer levels it was quite effective in dimer removal. The rates of repair in soybean were substantially higher than in alfalfa seedlings at the same DNA damage levels.