Metabolomic changes in Arabidopsis thaliana exposed to extracellular self- and nonself-DNA: A reversible effect

Untargeted metabolomics analysis was used to assess at molecular level the plant reactions to extracellular DNA (exDNA) exposure. Thus, the effects on the metabolites profile of A. thaliana after exposure to self-and nonselfDNA have been investigated by NMR, LC-MS and chemometrics analyses. Results confirmed that self-DNA significantly induces the accumulation of different RNA constituents along with their cyclic analogues, in form of cyclic dimers, as well as methylated forms, increasing only in the self-DNA treatment. In addition, a deeper investigation of these samples showed the increase of several metabolites belonging to the classes of indoles, flavonoids, thiazoles and isothiocyanates. All these metabolites are known to be involved in plant growth and defence. Among these, isothiocyanates are known to affect the A. thaliana cell cycle with accumulation of cells in S-phase which is consistent with observations of self-DNA inhibition in other model organisms. Noteworthy, the early metabolomic changes induced by self-DNA were shown to be reversible when followed by a second exposure to extracellular nonself-DNA. These results highlight the relevance of the environmental balance between self-and nonself-DNA in the regulation of plant metabolism.