Verification of a novel type of resistance genes conferring resistance to barley leaf scald caused by Rhynchosporium secalis
(DFG RO 1055/10-1; 2011-2014)
The goal of the proposed research is the functional verification of the Rrs2 gene rendering resistance against the fungal pathogen Rhynchosporium secalis in barley. In previous research the fine mapping of Rrs2 provided a genomic region cosegregating with Rrs2, which contained several predicted pectinesterase inhibitor genes and a number of other genes (Hanemann et al. 2009). We will establish a virus induced gene silencing system (VIGS) to test the cosegregating candidate genes functionally for their ability to break down Rhynchosporium resistance by RNAi. Additionally, the candidate genes for Rrs2 will be stably over-expressed in the Rhynchosporium-susceptible barley variety ‘Golden Promise’ in collaboration with the research group ‘Plant Reproductive Biology’ and the transgenic lines will be analysed for their resistance. This research will lead to the functional characterization and verification of the Rrs2 gene, which potentially constitutes a novel type of resistance gene. After verification of the Rrs2 gene the expression pattern upon Rhynchosporium infection will be studied in detail.
Map-based cloning and functional validation of a QTL for grain size in wheat
(DFG RO 1055/11-1; 2012-2015)
QTL Q.Tgw.ipk-7D increases grain size in wheat and also has positive effects on total grain mass and harvest index. By genetic methods, it was shown that a Mendelian gene inherited in recessive fashion is causing these effects (Röder et al. 2008). Our aim is the molecular identification and functional verification of the wheat gene underlying the QTL Q.Tgw.ipk-7D affecting grain size. The QTL interval was genetically delimited by fine mapping and synteny studies with rice and Brachypodium distachyon revealed a good synteny for the investigated region. The area of interest harbours 36 and 42 genes in rice and Brachypodium, respectively. Among them is a possible candidate gene for QTL Q.Tgw.ipk-7D encoding an AP2 domain containing protein. Further fine mapping is expected to narrow down the list of possible candidate genes for QTL Q.Tgw.ipk-7D. Therefore, the ongoing map based cloning approach is to be continued and obtained candidates are to be tested for their functionality in stably transformed wheat lines in collaboration with the research group ‘Plant Reproductive Biology’.
The molecular identification of QTL Q.Tgw.ipk-7D will provide novel insight in the heritable regulators of grain size in wheat and would constitute the first cloned QTL reported in wheat.
VALID: Validation and identification of important marker/trait associations for traits of agronomic importance towards the development of improved wheat varieties
In a consortium with industrial partners marker trait associations will be validated for their use in variety development. In a panel of winter wheat varieties association genetics studies will be performed for yield, yield parameters, drought stress tolerance and resistance towards some fungal pathogens. For the validation of marker trait associations bi-parental mapping populations will be developed and evaluated. Genotyping will be performed using SSR as well as genic SNP markers. The genotypic marker data and the phenotypic trait data will be combined and analyzed in statistical analysis.
Marker trait associations with importance for breeding found in this project have the potential to be used for the development of better yielding wheat varieties. However, the best strategy still has to be determined. Therefore specific population development will support strategies to use specific marker trait associations for variety development.
SELECT: Selection and identification of molecular markers in specific genomic regions of agronomic importance and for general mapping in allopolyploid wheat for accelerated breeding
In a consortium with industrial partners novel methods for the enrichment and identification of SNPs in targeted genes will be tested and optimized for the development of molecular markers for breeding of polyploid crop species and the study of genetic variability in specific chromosomal regions.
We will use the techniques ‘sequence capture’ and ‘next generation sequencing’ for identification of SNPs in the hexaploid crop species wheat. Several genomic regions carrying QTLs or associations of agronomic importance will be specifically enriched with molecular markers. Additionally, we will develop a saturated genetic map for chromosomes of group 6 in wheat in collaboration with the physical mapping project of wheat chromosome 6A called ‘Tritex’.
The project will deliver experiences for marker development of targeted regions in a polyploid large-genome crop species.