Heritability of stress-induced chromatin changes: a review
The role of epigenetics in general, and chromatin changes in particular, in how organisms respond to a variety of stresses is a subject of hot debate. Together with the recent discovery that some epigenetic changes can be stably inherited over generations, this has raised the possibility that some stress-induced epigenetic changes may be heritable. In this review article, Ales Pecinka and Ortrun Mittelsten-Scheid discuss the recent evidence on the heritability of stress-induced chromatin changes and conclude that to claim significant heritability a number of specific criteria need to be met.
Pecinka A, Mittelsten Scheid O (2012) Stress-induced chromatin changes: a critical view on their heritability. Plant Cell Physiol online: 28 March 2012.
The investigation of stress responses has been a focus of plant research, breeding, and biotechnology for a long time. The insight into stress perception, signalling, and genetic determinants of resistance, has recently been complemented by growing evidence for substantial stress-induced changes at the chromatin level. These affect specific sequences or occur genome-wide and are often correlated with transcriptional regulation. The majority of these changes only occur during stress exposure, and both expression and chromatin states typically revert to the pre-stress state shortly thereafter. Other changes result in the maintenance of new chromatin states and modified gene expression for a longer time after stress exposure, preparing an individual for developmental decisions or more effective defence. Beyond this, there are claims for stress-induced heritable chromatin modifications that are transmitted to progeny, thereby improving its characteristics. These effects resemble the concept of Lamarckian inheritance of acquired characters and represent a challenge to the uniqueness of DNA sequence-based inheritance. However, with the growing insight into epigenetic regulation and transmission of chromatin states, it is worth investigating these phenomena carefully. While genetic changes (mainly transposon mobility) in response to stress-induced interference with chromatin are well documented and heritable, in our view there is no unambiguous evidence for transmission of exclusively chromatin-controlled stress effects to progeny. We propose a set of criteria that should be applied to substantiate the data for stress-induced, chromatin-encoded new traits. Well-controlled stress treatments, thorough phenotyping, and application of refined genome-wide epigenetic analysis tools should be helpful in moving from interesting observations towards robust evidence.
16 April 2012