Chapter 35 - Transgenerational genome instability in plants

Abstract

DNA replication is a faithful duplication of genetic material that ensures the inheritance of the exact genetic code upon somatic and meiotic cell divisions. This is critically important for the survival of an organism in the stable environment. In contrast, the survival under stressful conditions requires drastic measures, and genetic mechanisms may not be able to provide a quick and efficient response. That is where epigenetics comes into play. Several recent reports suggest that the progeny of plants exposed to stress exhibit changes in stress tolerance, DNA methylation, mRNA and noncoding RNA transcriptome as well as in genome stability. It is hypothesized that such response is caused either by presence of certain stress-induced molecules in the germline or by the establishment or erasure of certain epigenetic marks. Whereas the former one could result in so-called intergenerational response to stress, and is unlikely to last beyond one-two generations, the latter one causes true transgenerational response that may last for several generations or lead to rather permanent epimutations. Many of the mechanisms of transgenerational responses are epigenetic in nature, and the increased genome instability in the progeny of stressed plants may be one of the mechanisms of acquiring new traits in unstable environments. Here, we describe changes that occur in response to stress at the level of genome stability and epigenome regulation and discuss the role of transgenerational responses to stress in plants in the regulation of genome stability.