How proteomics contributes to our understanding of drought tolerance

Drought is a ubiquitous threat to plant performance, whether in crops or natural ecosystems. Acclimation responses to drought have been loosely categorised as escape, avoidance or tolerance, with a gradual reversal of these events once water is re-supplied. Many analytical disciplines have been brought to bear on plant organs and tissues experiencing water deficit, including biophysics, physiology and the various -omics technologies. One such technique, proteomics, is supported by an ever-expanding array of technologies that have evolved from two-dimensional gel electrophoresis and sequencing to various label and label-free techniques that yield progressively deeper insights into gene expression. These experiments reveal major changes in abundance of ABA-responsive proteins, heat shock proteins and proteins involved in defence against oxidative damage. More surprising is the commonly reported changes in proteins participating in energy metabolism and down-regulation of photosynthetic proteins. Such experiments have been greatly enabled by the exploitation of known genetic variation in ‘drought tolerance’ in cereals, with the acknowledgement that yet more drought resistance mechanisms are certain to exist in unrelated arid-zone species. The next step will be to interrogate large-scale data sets and construct gene networks (interactomes) for a more meaningful understanding of the drought phenotype.