DNA Events

Plant Pathogens Trigger DNA Recombination

Science's STKE  17 Jun 2003:
Vol. 2003, Issue 187, pp. tw230-TW230
DOI: 10.1126/stke.2003.187.tw230

In plants, DNA rearrangement can be stimulated by various environmental and pathogenic stresses. Kovalchuk et al. designed a luciferase reporter assay that depended on DNA recombination events to visualize stimulation of DNA rearrangement in virally infected tobacco plants. The recombination events occurred in leaves that did not yet contain detectable virus. Stimulation of DNA rearrangement preceded spread of the virus to uninfected leaves and could be transmitted to uninfected plants by grafting of uninfected leaves from plants exposed to virus on other leaves. These results indicated that the pathogen itself was not causing DNA rearrangement directly, but rather that the virus activated a signaling cascade that triggered the increased recombination rate. The results were confirmed by following recombination frequencies of an endogenous gene. Increased frequency of recombination in plants grown from seeds of plants grafted with leaves from infected plants was also noted. The authors propose that a mobile signal, the systemic recombination signal, is generated in response to viral infection that stimulates DNA rearrangement throughout the plant. This signal did not appear to be the same as that involved in systemic acquired resistance.

I. Kovalchuk, O. Kovalchuk, V. Kalck, V. Boyko, J. Filkowski, M. Heinlein, B. Hohn, Pathogen-induced systemic plant signal triggers DNA rearrangements. Nature 423, 760-762 (2003). [Online Journal]