Abstract
TMV-RNA inactivated by irradiation at wavelengths in the region of 300 m[mu] exhibits an increased photoreactivable sector with respect to that observed following 253.7 m[mu] irradiation. The amount of the photoreactivable lesion similar to that formed by 253.7 m[mu] irradiation is increased by the near UV irradiation, and the formation of a new type of repairable lesion is inferred from the dark-holding effect and the variation in apparent infectivity on assay plants grown under high- and low-intensity illumination.