Understanding the relationship between stress response and epigenetic regulation in plants: the long and winding road

Evolution of organisms relays on the selection of the genotypes that are better adapted to a specific environment. The laws of genetics irrefutably support this scientific evidence famously proposed by Charles Darwin in 1859 and which, probably, changed the relationship of humans with the world. In many texts regarding epigenetics it is often mentioned the visionary perspectives of Lamarckian theories on soft inheritance as primordial observations of epigenetic inheritance. Lamarck theories proposed that the environment can directly alter the phenotype and that these changes are heritable. It is tempting in the era of genome-wide sequencing to speculate that not all our genetic information is contained within the genome. Although there are examples of epigenetic regulation in humans, plants offer remarkable cases of epigenetic regulation of traits and are great model systems to study the influence of this type of regulation in different aspects.

During their life cycle, plants face environmental factors that determine the extent of their geographical distribution and impact their growth and their reproductive capacity. In agricultural plants, these factors are considered stresses that enormously affect yield potentials and by hence human health. Plants lack a specialized immune system to cope with biotic and abiotic stress. Instead, plants have complex regulatory networks that determine the appropriate distribution of resources between the developmental and the defense programs. Like other eukaryotic organisms, plants have different layers of epigenetic regulation whose main role is to control the expression of transposable elements (TEs) and, occasionally, genes. Epigenetics adds plasticity to gene expression allowing their regulation without altering their DNA sequence. The epigenetic status of some of those genes can be influenced by environmental conditions, Indeed, epigenetic regulation of repeats and gene expression has evolved as an important player in the transcriptional regulation of stress-related genes.

In my docent lecture, I will review the current knowledge on how different stresses interact with different levels of epigenetic control of the genome. Research in my group indicates that different biotic stresses cause alterations at different levels of the epigenetic regulatory pathways and influence the expression of different sets of genomic entities. Although yet to be understood completely, the interplay between epigenetics and stress resistance seems to be a relevant and dynamic player of the interaction of plants with their environments. This interaction which offers exciting new opportunities to understand the flexibility of genomes, the evolution of this elasticity and the potential of plant genomes to build resilience against stress.