Orchestration of plant defense systems: genes to populations

•Plants integrate across all levels of defense and development.•Plants may detect and respond to sets of signals rather than to specific organisms.•Defense compounds are transported across cells and tissues, complicating the interpretation of cell autonomy.•Plant defense compounds may have regulatory influence on plant responses.

Research over the past decades has made immense progress in identifying some genes and mechanisms underlying plant defense against biotic organisms. The recent movement towards systems biology approaches has increased mechanistic knowledge, revealing a need for understanding how all the genes and mechanisms integrate to create a response to any given biotic interaction. This begins with evidence that diverse molecular patterns converge, suggesting that the plant perceives signals not the interacting species. These signals then coordinate across regulatory networks via molecular interactions and cause non-cell autonomous responses in neighboring and systemic cells. Finally, the identification of transporters is showing that plant defenses are harmonized across tissues and even show the potential for coordination across individuals within a population.