Defense on multiple fronts: how do plants cope with diverse enemies?

Plants have evolved an array of defense mechanisms to protect themselves against the wide variety of pathogens and pests with which they are confronted. Included in these defense mechanisms are inducible responses that are turned on systemically in the plant in response to attempted infection or predation. The two most studied inducible responses are systemic acquired resistance, which provides enhanced resistance to pathogen infection, and the wound response pathway, resulting in enhanced resistance to insect feeding. Recent research suggests that the two pathways are not completely independent, and the induction of one might affect the expression of the other. However, the evidence for cross-talk between different induced defense response pathways is somewhat confusing, and at times contradictory. Here, we review recent advances in our understanding of how the different pathways might interact.