Proteomics: State of the art to study Mediterranean woody species under stress

Mediterranean woody species are vulnerable to multiple stresses that negatively affect plant survival and productivity. Drought and heat are increasing threats to the agricultural and forestry systems, making it urgently necessary to determine the mechanisms of plant adaptation and survival. Proteomics allows for the characterisation of a large number of proteins in a given tissue/organ, providing an integrated picture of the molecular events involved in stress responses. In this paper, we have evaluated the contribution of proteomics for the identification of stress-responsive proteins and tolerance/adaptation mechanisms in woody plants of agronomic importance in the Mediterranean basin. A systematic review was performed (Web of Knowledge, 5th March 2013) on the relevant genera for this region: Quercus sp., Pinus sp., Eucalyptus sp., Vitis sp., Olive sp., and Citrus sp. The term Rosaceae was also included in the search due to the relevance of fruit tree crops of this family in the Mediterranean region. This systematic review highlighted the lack of extensive and comprehensive proteomic analyses for Mediterranean plants under stress. The approach retrieved 19 and 38 papers concerning the assessment of abiotic and biotic stresses, respectively, at the proteome level, and 20 and 46 papers, respectively, concerning analyses at the transcriptomics level. With regard to abiotic stress, gel-based proteomic methodologies (15 papers) enabled the identification and quantification of 395 stress-responsive proteins. These results revealed metabolic adjustments to stress, with major alterations in carbon, nitrogen, and amino acid metabolisms. The most consistently represented stress-responsive proteins were RuBisCO, RuBisCO activase, heat shock proteins, chlorophyll a/. b binding protein, and proteins from the oxygen-evolving complex. We concluded that gel-based proteomics revealed key proteins and metabolic pathways important for the ability of plants to adjustment to environmental fluctuations. The integration of this information with physiological, agronomic, and technological performance (e.g. survival, productivity, and food and technological quality) is essential for the sustainable development of the Mediterranean regions.