Technologies for barley improvement in the post-marker era

Molecular markers linked to genes of commercial value have greatly accelerated the development of improved crop varieties and this technology has been widely applied to barley. The technology continues to improve. The number of traits with linked markers has increased, the strength of the association between marker and trait has been improved and the cost and ease of maker analysis improves continually. The ultimate limit of these approaches will be reached when traits are analysed in very high through-put at very low cost by analysis of the plant DNA sequence responsible for the trait rather than a linked marker. This stage is being approached more rapidly in species such as rice for which a complete genome sequence is available. The analysis of very large numbers of DNA sequences in a plant sample is now possible for relatively low cost. We now employ several levels of technology for analysis at different levels of through-put. Real-time PCR and automated mass spectroscopy proved screening tools for sequence differences identified using several different DNA sequencing platforms. Size separation (di deoxy sequencing), biochemical reactions (pyrosequencing) and analysis of the mass of DNA fragments are key techniques for DNA sequence analysis. Data on the sequences of barley genes is growing rapidly. Allele specific analysis of the key genes in barley will provide a robust approach to rapid delivery of new genotypes for commercial production.