Investigation of transitive and systemic RNA silencing in plants
German Research Foundation (DFG), duration 02/16-01/19
After RNAi-mediated cleavage the RNAs are usually completely degraded. However, in plants occasionally some of the target transcripts are transcribed into so-called secondary dsRNAs by RDRs (Wassenegger and Krczal, 2006). Similar to primary dsRNA, secondary RNAs are processed by DCLs leading to the production of secondary siRNAs. This process propagating in the 5 'and 3' direction from the primary target region is called transitivity or transitive silencing. The mechanistic details of transitivity are largely unknown. In addition to transitivity, so-called systemic silencing is found in plants. Signals traveling over long distances can be produced in cells in which local silencing has been activated. In cells receiving such signals, systemic silencing of homologous transcripts can be induced. Interestingly, for unknown reasons, transcripts of transgenes are generally much more susceptible to transitivity and systemic silencing than endogenous transcripts (Dadami et al., 2013, Dadami et al., 2014).
We are currently investigating whether the introduction of a putative RNAi trigger is sufficient to initiate systemic silencing. Moreover, we are investigating how transitivity and systemic silencing of transgenic versus endogenous target transcripts are initiated. The use of synthetic siRNAs allows for the first time to study the nature of RNAi triggers accurately (Dalakouras et al., 2016).
Genes and mutants affecting virus infection in rapeseed (GAMAVIR)
Federal Ministry of Education and Research (BMBF), Transnational Plant (genome) Research (Plant-KBBE), Project number: 031A324, Running time: 04/2014-03/2018
The project is continued by in-house funding.
The goal of GAMAVIR was to unravel the role of small RNAs (sRNAs) in the fine–tuning of gene expression during virus infection in Rapeseed (Brassica napus). Genes that are targeted by sRNAs during infection may represent useful targets for the breeders. Such genes were to be identified and subsequently mutated to confirm their function during infection in this crop.