Analysis of viral and bacterial pathogenesis has revealed common theme
s in the ways in which plants and animals respond to pathogenic agents
, Pathogenic bacteria use macromolecule delivery systems (types III an
d IV) to deliver microbial avirulence proteins and transfer DNA-protei
n complexes directly into plant cells, The molecular events that const
itute critical steps of plant-pathogen interactions seem to involve li
gand-receptor mechanisms for pathogen recognition and the induction of
signal transduction pathways in the plant that lead to defense respon
ses. Unraveling the molecular basis of disease resistance pathways has
laid a foundation for the rational design of crop protection strategi
es.