Epigenetics and the evolution of virulence

• Pathogens must evolve rapidly in response to host or environmental challenges.
• Clonal and invasive species adapt quickly despite a lack of genetic diversity.
• Evasion of host immunity can result from silencing of relevant effectors.
• Epigenetic reprogramming of gene expression can aid in pathogen adaptation.

A feature of pathogenic and invasive organisms is their adaptability when confronted with host and environmental challenges. Recent studies have demonstrated that plant pathogens rely on epigenetic processes for this purpose. Epiallelic variation of effector genes that results in evasion of host immunity is one emerging phenomenon. Another is the epigenetically induced reprogramming and diversification of transcriptional patterns by de-repression of transposable elements. These observations indicate that epigenetic control of gene expression provides a versatile means of generating phenotypic diversity that is adaptable and heritable across generations.