A devil's bargain with transposable elements in plant pathogens

Transposable elements (TEs) spread in genomes through self-copying mechanisms and are a major cause of genome expansions. Plant pathogens have finely tuned the expression of virulence factors to rely on epigenetic control targeted at nearby TEs. Stress experienced during the plant infection process leads to derepression of TEs and concurrently allows the expression of virulence factors. We argue that the derepression of TEs elements causes an evolutionary conflict by favoring TEs that can be reactivated. Active TEs and recent genome size expansions indicate that plant pathogens could face long-term consequences from the short-term benefit of fine-tuning the infection process. Hence, encoding key virulence factors close to TEs under epigenetic control constitutes a devil’s bargain for pathogens.