Barley Proteomics

The present chapter summarizes the current status of proteome research on barley. The importance of barley as a model for cereals and as a major crop is reflected by a large number of publications using proteomics as an approach to address fundamental or applied research questions. Progress through technological developments in mass spectrometry, the central analytical technique in proteomics, forms the background methodology applied for protein or peptide separation and protein identification as outlined in the first section. The grain is of central relevance for the use of barley as a crop and seed biology is a central topic in plant science. Hence, a large number of studies focus on the grain proteome as well as the changes in proteome composition during grain maturation and germination. Separate sections cover research on abiotic and biotic stress defence responses. The next section is dedicated to subcellular proteomics, isolation of organelles or subcellular fractions being a powerful strategy to cope with the complexity of the plant proteome. Typical current analytical tools can cover only a small fraction of the complete proteome. With regard to the number of genes, any proteome is increased in complexity by a high number of post-translational modifications and many potential splicing variants. In addition, the dynamic range of the individual protein abundance covers many orders of magnitude exceeding the limits of current detection methods. Although this complexity of the proteome is demanding for in-depth protein analysis, information on, e.g. post-translational modifications cannot be derived from other approaches such as transcriptomics. These aspects and potential developments are addressed in the final section of our contribution.