Genetics of proteome variation for QTL characterization: application to drought-stress responses in maize

The proteome is emerging as an important concept of the post-genome era. Powerful nucleic acid approaches (EST, DNA chips, etc.) are still limited because DNA sequences and mRNA levels are not sufficient to predict the structure, function, amount, and activity of the proteins in the cell, The proteome can now be subjected tb large-scale analysis, owing to spectacular progress in the techniques of identification of proteins excised from two-dimensional (2-D) gels. in addition, computer-based analysis of 2-D gels makes it possible to quantify the protein spot intensities, which are commonly genetically variable. The loci controlling these variations may be mapped on the genome (PQLs, Protein Quantity Loci), Beyond the interest for regulatory genetics and molecular biology, the PQL methodology can provide an additional tool for the difficult task of identifying QTLs (Quantitative Trait Loci), in the context of the candidate gene approach. The PQL methodology is presented with the example of the phosphoglycerate mutase Variations in maize, and the candidate gene/protein approach is illustrated for traits responsive to drought stress.