Root cell death and systemic effects of Piriformospora indica: a study on mutualism.

The root systems of most terrestrial plants are confronted with a huge variety of invasive microorganisms that either can cause detrimental effects or in case of mutualistic symbiosis provide benefits for the host. In either case, establishment of the parasitic or mutualistic interaction is the result of a highly sophisticated cross-talk between the partners. Despite the ecological importance of mutualistic symbioses, the molecular events accompanied by this phenomenon are far from being understood. Piriformospora indica represents a recently discovered fungus that transfers considerable beneficial impact to its host plants. In this review, the current knowledge on this novel symbiosis is summarized by focusing on its biological effects in hosts and the role of programmed cell death in the establishment of the mutualistic interaction.