Photoreversible Ultraviolet Enhancement of Infectivity in Agrobacterium tumefaciens

Heberlein, Gary T. (Northwestern University, Evanston, Ill.), and James A. Lippincott. Photoreversible ultraviolet enhancement of infectivity in Agrobacterium tumefaciens. J. Bacteriol. 89:1511-1514. 1965.-Irradiation of a virulent strain of Agrobacterium tumefaciens with short-wavelength ultraviolet light, which reduces viability 50 to 90%, increases its infectivity as measured by the number of tumors initiated per viable bacterial cell on primary pinto bean leaves. A dark treatment of 1.5 to 2 hr between irradiation and inoculation results in a further increase in specific infectivity of as much as fourfold. This increase in infectivity is inhibited by white fluorescent light and light of 402 mmu, but only slightly by 549- or 619-mmu light. These results imply that some change in the deoxyribonucleic acid of the bacterium is responsible for this effect.