Recent developments in the application of proteomics to the analysis of plant responses to heavy metals

Pollution of soils by heavy metals is an ever-growing problem throughout the world, and is the result of human activities as well as geochemical weathering of rocks and other environmental causes such as volcanic eruptions, acid rain and continental dusts. Plants everywhere are continuously exposed to metal-contaminated soils. The uptake of heavy metals not only constrains crop yields, but can also be a major hazard to the health of humans and to the entire ecosystem. Although analysis of gene expression at the mRNA level has enhanced our understanding of the response of plants to heavy metals, many questions regarding the functional translated portions of plant genomes under metal stress remain unanswered. Proteomics offers a new platform for studying complex biological functions involving large numbers and networks of proteins, and can serve as a key tool for revealing the molecular mechanisms that are involved in interactions between toxic metals and plant species. This review focuses on recent developments in the applications of proteomics to the analysis of the responses of plants to heavy metals; such studies provide a deeper understanding of protein responses and the interactions among the possible pathways that are involved in detoxification of toxic metals in plant cells. In addition, the challenges faced by proteomics in understanding the responses of plants to toxic metal are discussed, and some possible future strategies for meeting these challenges are proposed.