Genetic variation for resistance to herbivores and plant pathogens: hypotheses, mechanisms and evolutionary implications

The interactions between plants and enemies employ a variety of mechanisms, which in turn affect the long-term evolutionary histories of the interacting species. Different patterns of interactions determine not only the selective forces acting on individual genes, but also the flexibility and rapidity of evolution in response to new threats. New genomic techniques allowing large-scale comparisons within and between species demonstrate that defence genes are highly variable and experience very different selective patterns even in recently diverged species. Similar and even shared pathways for defence against diverse taxa of enemies reveal the variability and flexibility of plant defence.