Cell biology of fungal and oomycete infection of plants

In order to infect host plants, fungal and oomycete plant pathogens must overcome highly effective, constitutive physical and chemical barriers to pathogen ingress. They must avoid inducing additional host defences, and they must deploy mechanisms for obtaining from the plant the nutrients they need for growth and reproduction. Successful pathogens employ a range of infection strategies most of which include the key steps of adhesion to the plant surface, location of optimal penetration sites, penetration of the plant surface and acquisition of nutrients from the plant cells. Recent studies have greatly increased our understanding of the cellular and molecular mechanisms that underlie the infection process and we now have more information on the nature of pathogen adhesives, on the role of the cytoskeleton in hyphal growth and differentiation and on signalling molecules that regulate the development and function of a variety of specialised infection structures. Advances in technologies that allow broad scale gene discovery and determination of gene function are also bringing with them an explosion in our knowledge of genes and proteins involved in plant infection. In this chapter, these new data are reviewed in the context of our understanding of the cell biology of the infection process, from the arrival of fungal and oomycete pathogen spores at the plant surface, through to the establishment of feeding structures within the plant tissues