Last database update for these data: 2008-10-14 - Data extracted on 2009-04-14 from the database.
| No | Title | Participants | Period | Description | Crops | Viruses | Host plants | Funding | URL |
|---|---|---|---|---|---|---|---|---|---|
| 1 | RNA-directed DNA methylation (RdDM) | Michael Wassenegger (Leader) Kajohn Boonrod Mirko Moser Nora Schwind Michèle Zwiebel Athanasios Dalakouras |
2004 - 2009 | In plants, RNA-directed DNA methylation (RdDM) represents one of the mechanisms that leads to establishment of de novo methylation patterns. Interestingly, not only RdDM but also transcriptional (TGS) and post-transcriptional gene silencing (PTGS) are initiated by double stranded RNA (dsRNA). Gene imprinting and X-chromosome inactivation in mammals seem to be correlated with production of sense/antisense RNA and with occurrence of de novo DNA methylation. Thus, it is reasonable to assume that RdDM also exists in mammals and that it is involved in epigenetic processes. In order to find evidence for this hypothesis, RdDM which is still barely characterised should be investigated in a plant system. With the expected data it could be possible to analyse whether de novo methylation can be directed by RNA in mammals. | Tobacco | Potato spindle tuber viroid | Nicotiana tabacum Nicotiana benthamiana |
EU STREP, Function of small RNAs across kingdoms (FOSRAK) http://www.fosrak.org/ (terminated 12/31/2007) EU IP, Silencing RNAs: organisers and coordinators of complexity in eukaryotic organisms (SIROCCO) http://www.sirocco-project.eu/ |
Specific Web page |
| 2 | RNA-directed RNA polymerases (RDRs) | Michael Wassenegger (Leader) Kajohn Boonrod Mirko Moser Nora Schwind Michèle Zwiebel Athanasios Dalakouras |
2004 - 2009 | In plants, four RDR homologues are presumably expressed. RDR1 seems to be directly involved in a virus defense mechanism. RDR2 is associated with nuclear processes (nuclear RNAi) and is essential for RNA-directed DNA methylation (RdDM). RDR6 is one of the key enzymes of post-transcriptional gene silencing (PTGS) and is mainly active in the cytoplasm. So far, no data have been published on the biological function of the RDR3a-3c homologues. To gain further information about the functionality of these enzymes all RDR cDNA sequences were isolated from N. tabacum. They will now be specifically inactivated in tobacco plants to analyze possible effects on PTGS, to examine variations in virus accumulation and to characterize the establishment of de novo DNA methylation patterns. In addition, tagged RDRs will be expressed in tobacco to identify RNA or protein components that associate with RDRs. Characterization of the components should help to extend our current knowledge on PTGS and RdDM. | Tobacco | Potato spindle tuber viroid | Nicotiana tabacum Nicotiana benthamiana |
EU STREP, Function of small RNAs across kingdoms (FOSRAK) http://www.fosrak.org/ (terminated 12/31/2007) EU IP, Silencing RNAs: organisers and coordinators of complexity in eukaryotic organisms (SIROCCO) http://www.sirocco-project.eu/ |
Specific Web page |
| 3 | Viroid Research | Michael Wassenegger (Leader) Nora Schwind Michèle Zwiebel |
2004 - 2006 | Viroids are the smallest known pathogens. They are circularly closed RNA molecules, exclusively infect plants and in Europe, they are detectable in grape vine, hop and citruses. However, they are also found in ornamental plants, e.g. Chrysanthemum and Coleus. Two viroids, the potato spindle tuber viroid (PSTVd) and the chrysanthemum stunt viroid (CSVd) are classified as quarantine pathogens. This classification caused major problems for ornamental plant breeders as they must guarantee that only viroid-free Chrysanthemum plants are brought on the market. In contrast to that the coleus blumei viroid (CbVd) is not registered. Interestingly, we could show that all Coleus plants on the Euopean market that we analyzed were heavily infected with CbVd. | Coleus blumei viroid 1 Coleus blumei viroid 2 Coleus blumei viroid 3 Chrysanthemum stunt viroid |
in house funding | |||
| 4 | Viroid Resistance | Michael Wassenegger (Leader) Nora Schwind Michèle Zwiebel |
2006 - 2009 | Because of their highly ordered structure, mature viroid RNA molecules were assumed to be resistant to degradation by RNA interference (RNAi). Here we report that a transgenic tomato plant line expressing a hairpin construct derived from Potato spindle tuber viroid (PSTVd) sequences exhibited resistance to PSTVd infection. This was correlated with the high level accumulation of hairpin-derived short interfering RNAs (siRNAs) in the plant. Thus, in contrast to small RNAs produced in PSTVd-infected non-transgenic plants (srPSTVds), these hairpin-derived siRNAs (hp-siRNAs) appeared to efficiently target the mature viroid RNA. Genomic mapping of the hp-siRNAs revealed an unequal distribution of 21 and 24 nt siRNAs of both (+)- and (-)-strand polarities along the PSTVd genome. These data suggest that RNAi can be employed to engineer plants for viroid resistance, as has been well established for viruses. | Potato spindle tuber viroid | Lycopersicon esculentum | in house funding | ||
| 5 | Viroid Monitoring | Michael Wassenegger (Leader) Nora Schwind |
2006 and after | In Europe, United States and Australia, PSTVd is classified as a quarantine pathogen. Infection of potato and tomato plants can lead to massive crop losses. Since late 2006, an epidemic outbreak of PSTVd in ornamental plants Solanum jasminoides, S. rantonnetii and Brugmansia spp. has been reported in at least the Netherlands, Germany and Italy. In contrast to tomato and potato, these ornamental plants do not develop visible disease symptoms with PSTVd infection. Unfortunately, infected plants were already widely distributed throughout Europe before viroid detection. Since transmission to crop plants is always a potential threat and PSTVd-resistant tomato and potato plants are not available, the production and distribution of ornamental PSTVd host plant species have been restricted. The restriction has severe economic impact on European plant producers, arguing for the availability of PSTVd-resistant crop plants. | Ornamental plants | Potato spindle tuber viroid Chrysanthemum stunt viroid Citrus exocortis viroid Columnea latent viroid Iresine viroid 1 Mexican papita viroid Tomato apical stunt viroid Tomato chlorotic dwarf viroid Tomato planta macho viroid |
Solanum laxum Lycianthes rantonnei Brugmansia |
in house funding | |
| 6 | HC-Pro silencing suppressor | Michael Wassenegger (Leader) Marc Füllgrabe |
2007 - 2009 | It is important to understand the mechanisms of symptom development in response to virus infection to design new strategies to produce virus resistant plants. In general, symptoms induced by potyviruses are based on the cellular effects of one of their proteins, the helper-component proteinase (HC-Pro). In plants, the HC-Pro interferes with small RNA metabolism and function, and such interference is associated with anomalous plant development. The central region in the HC-Pro is associated with suppressor activity and RNA binding. A mutation within a highly conserved amino acid (FRNK) motif of the zucchini yellow mosaic virus (ZYMV) HC-Pro dramatically changes the severe wild type strain to an asymptomatic strain, but does not affect its accumulation in squash plants and suppressor activity is maintained. The ability of this mutation to uncouple symptoms from virus accumulation creates a unique opportunity to study the etiology of symptoms. In other potyviridae such a mutation in the HC-Pro always resulted in loss of infectivity. Our goal is to determine how this and other mutations in this conserved ZYMV HC-Pro motif affect host responses to potyvirus infection in cucurbit plants. In particular, we will focus on the effect of HC-Pro on small RNA accumulation. | Zucchini yellow mosaic virus | Nicotiana benthamiana | Germany Research Foundation (DFG) | Specific Web page | |
| 7 | Production of recombinant proteins in plants | Michael Wassenegger (Leader) Katharina Klut Michèle Zwiebel Nora Schwind |
2007 - 2009 | In order to promote health protection, the subsidy of tobacco production will be discontinued, step by step. To safeguard the future income of the producers, Brussels is currently looking at alternatives. It mainly favours the conversion of tobacco production to other crops. It is, however, questionable whether the production of alternative crops to tobacco can completely compensate for the loss of subsidies. A complete conversion of tobacco production in Rhineland-Palatinate may therefore not be expendient. For this reason, our work aims at utilising tobacco plants for other purpose than the production of cigarettes. Our aim is to develop an innovative strategy which allows a high production rate of economically interesting recombinant pharmaceutical proteins of in tobacco ("bioreactor"). For this purpose, a plant defence mechanism targeting the expression of foreign genes, which has until now severely limited the profitability of plants as bioreactors, shall be inhibited (For further details about the project see AlPlanta-FNR-Tobacco as Bioreactor. |
Nicotiana tabacum | Specific Web page | |||
| 8 | Identification of enzyme complexes involved in de novo DNA-methylation in living plant cells using Spectrally Assigned Localization Microscopy (SALM) | Michael Wassenegger (Leader) Mario Braun |
2008 - 2009 | In eukaryotic organisms, RNA-mediated heterochromatin formation is a powerful mechanism regulating many developmental processes and acting as a defence mechanism against foreign nucleic acids. At least in plants, heterochromatin formation is essentially initiated by DNA hypermethylation which in turn involves a sequence-specific de novo methylation process termed RNA-directed DNA methylation (RdDM). Only in plants, the function of most of the components associated with RdDM is well described rendering plants ideal model systems to study de novo DNA methylation. It is of broad interest to understand how DNA methylases are guided to their target sequences. However, to elucidate these dynamic processes it is essential to investigate living cells. We therefore aim at applying the 'Spectrally Assigned Localization Microscopy' (SALM) to monitor for the first time the in vivo formation of enzyme complexes involved in RdDM and their targeting. We wish to show the direction interaction of these complexes with the genomic DNA. At present, however, we do not know if the SALM technology will allow us to detect single enzyme complexes interacting with target regions along the chromosomes. | Nicotiana tabacum Nicotiana benthamiana |
University of Heidelberg, Frontier Project | |||
| 9 | Functional analysis of the P1 of Rice Yellow Mottle Virus | Michael Wassenegger (Leader) Isabel Weinheimer |
2008 - 2009 | Rice yellow mottle virus | Nicotiana benthamiana Arabidopsis thaliana |
in house funding |