Proteomic analysis of crop plants under abiotic stress conditions: where to focus our research?

Approximately 80% of human food is composed of crops, which are dominated by cereals that collectively make up 50% of global food production (Langridge and Fleury, 2011). Among cereal crops, rice, wheat, and maize provide approximately half of the calories consumed worldwide. Nevertheless, crop production is seriously hampered by influential abiotic stresses like drought, climate fluctuations, and salinity. It is estimated that up to 50–70% decline in crop productivity is attributed to abiotic stress (Mittler, 2006). Therefore, to ensure the security of global food production, it is essential to produce sustainable crop varieties that can adapt to climate variability, and to develop a broad spectrum of abiotic stress tolerant crops (Tester and Langridge, 2010). This has driven much research into the study of crop responses to abiotic stresses. Proteomics has been successfully used to study abiotic stress responses in a wide range of crops (Abreu et al., 2013; Barkla et al., 2013; Ngara and Ndimba, 2014), especially rice (Kim et al., 2014), wheat (Komatsu et al., 2014), and maize (Benesova et al., 2012; Gong et al., 2014). It is generally envisioned that at this stage, proteomic-based discoveries in rice are likely to be translated into improving other crop plants against ever-changing environmental factors (Kim et al., 2014). Despite the potential role of proteomics to advance the study of stress tolerance in crops, thus far little useful information has beenmade available for crop improvement and breeding, even with the numerous proteomics studies undertaken in recent years. In our opinion, crop stress proteomics should be better focused on the following aspects: dissecting cell specific stress response (especially initial stress responses), identification of stress proteins, and the analysis of post translational modifications (PTMs) of proteins (Figure 1).