Effect of plastid transcription on genome integrity in Arabidopsis

Transcription can be an important natural source of genome instability. For instance, it may generate RNA:DNA hybrids as the nascent transcript hybridizes with the complementary DNA template. These hybrids, called R-loops, act as a major cause of replication fork stalling and DNA breaks. In this study, we used mutant lines known to be defective in plastid transcription to evaluate the effect of this process on the accumulation of DNA rearrangements in plastids of Arabidopsis thaliana. Additionally, we developed transgenic lines expressing a plastid-targeted RNAseH1 to study the impact of resolving R-loops on plastid genome stability.