Development and implementation of advanced methods for the identification of barley flowering time genes using next generation sequencing

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Variation in flowering time has always been a major target in breeding programs to adapt crops to a wide range of environments. Deciphering the genetic basis of flowering time variation is thus important for knowledge based breeding of new varieties. Temperate crops like barley and wheat are characterized by large genomes mostly comprising of repeats. Even though these complex genomes are an extreme challenge to all genetic attempts, new technologies allow accessing the gene spaces of these large genomes in a fast and cost-efficient way. Albeit the first reports on simultaneous genetic mapping and mutation identification by next generation sequencing found their way into scientific literature, the continuing bottleneck for high throughput identification of causal mutations remains the appropriate methods and genetic material. Like conventional map-based cloning efforts, such high-speed mapping methods require segregating populations as their primary material. Here we propose to establish two new strategies for mutant identification in barley, which carry the promise to tremendously speed up the generation of mapping populations. First, we propose generation of isogenic mapping populations through self-fertilization of heterozygous mutants as recently proposed for rice. As such mutant plants can be identified within the M2 families of the original screens, it does require one a single generation to establish the segregating population. Second, sequencing of allelic mutants carries the promise to reveal causative genes without any linkage-based analysis, as it is usually only one gene or a very small number of genes that feature severe changes within all allelic mutants. Using nine different allelic series with two to six alleles in each group will unravel the power of this approach. Once established, both of these methods will allow for exploiting the extensive genetic resources of barley mutant populations generated over the last decades.