Identifizierung und funktionale Charakterisierung von Effektorkandidaten arbuskulärer Mycorrhizapilze
Mikrobielle Ökologie und Angewandte Mikrobiologie
Zell- und Entwicklungsbiologie der Pflanzen
Zusammenfassung der Projektergebnisse
The project based on the assumption that fungal secreted effector proteins play an important role during the AM symbiosis between plants and fungi of the genus Glomeromycota. Due to the broad compatibility range between plant and fungal AM symbionts, we would expect conservation of important effectors within the Glomeromycota. We successfully identified a list of genes encoding predicted effector proteins, conserved between R. clarus and R. rhizogenes. In our main approach we tried to directly investigate the role of putative effector proteins in AM symbiosis by expression downregulation in the fungus via host induced gene silencing (HIGS). For one candidate, RiTPS1, a trehalose synthase, we observed reduced root length colonization and smaller arbuscules in L. japonicus roots in one successful downregulation experiment. Subsequent HIGS approaches for this and a number of other genes failed for no apparent reason. However, it should be noted that despite numerous approaches by other groups, up to now only two successful HIGS approaches in Glomeromycota have been published. Although we did not achieve reproducible establishment of HIGS within this project, it is worthwhile to pursue this approach, because of its enormous potential for characterization of gene function in Glomeromycota. Functional analysis of the trehalose biosynthesis genes indicated that RiTPS1 most likely is not an effector protein, showing the limits of in silico prediction. However, our results indicate that in R. irregularis, RiTPS1 together with RiTLS2 and RiTPS2 fulfils very similar roles in trehalose metabolism as in other fungi, like S. cerevisiae. For another candidate effector, the PWWP domain-containing RcPdp, we were able to show in a transient tobacco leaf assay suppression of the plant hypersensitive response. We could also demonstrate an effect on nucleolus organisation, possibly by a change in chromatin organisation. The combination of phenotypical and cellular effects might indicate an involvement of this putative effector protein in the symbiotic interaction. Thus it is a prime candidate for further functional analysis in AM symbiosis. Overall, our list of predicted conserved effector candidates remains a valuable source for future discoveries.
Projektbezogene Publikationen (Auswahl)
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(2014) Identification of the arbuscular mycorrhizal fungi effector repertoire. 12th European Conference of Fungal Genetics (ECFG12), Seville
Sedzielewska K, Parniske M, Brachmann A
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(2014) Identification of the arbuscular mycorrhizal fungi effector repertoire. XVI International Congress on Molecular Plant-Microbe Interactions (IS-MPMI), Rhodes
Sedzielewska K, Parniske M, Brachmann A
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(2015) Conserved effectors in AM fungi. 2nd International Molecular Mycorrhiza Meeting (iMMM), Cambridge
Sedzielewska K, Hoffrichter A, Brachmann A
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(2015) Conserved effectors in AM fungi. 36th New Phytologist Symposium: Cell biology at the plant-microbe interface, Munich
Sedzielewska K, Hoffrichter A, Brachmann A
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(2015) Functional analysis of putative effectors in Rhizophagus irregularis by host induced gene silencing (HIGS). 2nd International Molecular Mycorrhiza Meeting (iMMM), Cambridge
Hoffrichter A, Sedzielewska K, Parniske M, Brachmann A
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(2016) The effector candidate repertoire of the arbuscular mycorrhizal fungus Rhizophagus clarus. BMC Genomics 17: 101
Sedzielewska Toro K, Brachmann A
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(2016) Trehalose biosynthesis in the arbuscular mycorrhizal fungus Rhizophagus irregularis. Gordon Research Conference: Cellular & Molecular Fungal Biology, Holderness, NH
Hoffrichter A, Sedzielewska Toro K, Brachmann A
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(2016) Trehalose biosynthesis in the arbuscular mycorrhizal fungus Rhizophagus irregularis. XVII International Congress on Molecular Plant-Microbe Interactions (IS-MPMI), Portland, OR
Hoffrichter A, Sedzielewska Toro K, Brachmann A
