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Dietrich Werner
antimicrobial factors concentrated around plant roots. Several multidrug
efflux pumps have been identified, e.g., in Rhizobium etli (González-Pasayo
and Martinez-Romero 2000).
Every specific symbiotic interaction has also to take a look to other strategies
of the symbiotic communication. There is increasing evidence that the
genetic requirements in the symbiotic interaction, e.g., between different Rhizobium
species, pathogens and arbuscular mycorrhiza fungi species with
their respective host plants, partially overlap (Parniske 2000). Different symbiotic
and pathogenic interactions finally branch to very specific functions
and nutrient exchanges. Common pathways and different aspects of symbiosis
and defense developments are fascinating aspects of future research
(Werner et al. 2002).
Acknowledgements. I thank the European Union for support in the INCO-DEV Project
ICA-CT-2001–10057, the JSPS, Japan, and Mrs Lucette Claudet for the excellent work for
this article.
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