To identify novel genes determining yield potential in an extended barley gene pool, Project 2 (Grain
yield) has introgressed the exotic wild barley accession ISR42-8 (Hordeum vulgare ssp spontaneum)
into the elite spring barley cultivar Scarlett (von Korff et al., 2006). Using marker-assisted selection,
multiple QTLs controlling grain yield and grain weight were mapped and verified in an advanced
backcross population and introgression lines (Schmalenbach et al., 2008; 2009). For the proposed
project, four introgression lines have been selected which show significant effects on grain yield and
grain weight. High resolution (HR) offspring populations have been developed for each introgression
line. In a first step, the HR offspring will be fine mapped, first with known SNP markers flanking the
original intro-gression and, second, with iSELECT SNP markers. Based on this genotyping,
recombination events leading to shorter introgressions will be selected among several thousand HR
lines. Informative recombinant HR lines will be used to phenotype grain yield and grain weight in
order to genetically fine map the SNP markers in close proximity to the QTL. The second step aims to
positionally clone verified QTLs, using available genome sequences from barley and other
graminaceous species to increase the chances of identifying all candidate gene sequences present
between the two closest flanking SNPs. In the final project phase, the exotic alleles of these
candidate genes will be amplified from the respective introgression lines and used for
complementation experiments through transformation of Scarlett as the recipient line. After
approval of a change of phenotype due to transformation, the cloned QTL will be available for new
research projects aiming at a detailed molecular and physiological characterization of the genetic
regulation of grain yield and grain weight in barley.