ARS | Publication request: Identification of salt-induced changes in leaf and root proteomes of the wild tomato solanum chilense

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 7, 2011
Publication Date: June 15, 2011
Citation: Zhou, S., Sauve, R., Liu, Z., Reddy, S., Bhatti, S., Hucko, S., Fish, T., Thannhauser, T.W. 2011. Identification of salt-induced changes in leaf and root proteomes of the wild tomato solanum chilense. Journal of the American Society for Horticultural Science. 136:288-302.

Interpretive Summary: Approximately 25% to 30% of the irrigated lands in the United States are negatively affected by high soil salinity levels. In tomato, repeated cultivation on the same land results in accumulation of residual fertilizers (salts) and contaminants from the irrigation water. For example, high salt concentration in the soil affects tomato fruit yield and quality, causing significant losses to many growers. Thus, in order to maintain tomato production at its current level without increasing costs, tomato cultivars tolerant to saline soil need to be developed. Some wild cultivars (e.g. Solanum chilense) are adapted to conditions of salt and/or drought stress. Here we carried out a study of protein expression using S. chilense as a model system to identify proteins whose expression was sensitive to elevated salt levels with a view towards identifying candidate genes to be used in future functional genomics studied and in the breeding of salt tolerant tomatoes. The set of proteins identified form the basis for a molecular level understanding of the mechanisms involved in salt tolerance.

Technical Abstract: This paper reports salt-induced changes in leaf and root proteomes after wild tomato (Solanum chilense) plants were treated with 200 mmol NaCl. In the leaf tissues, a total of 176 protein spots showed significant changes (P<0.05), of which 104 spots were induced and 72 spots suppressed. Salt induced proteins are associated with the following pathways: photosynthesis, carbohydrate metabolism, glyoxylate shunt, glycine cleavage system, branched-chain amino acid biosynthesis, protein folding, defense and cellular protection, signal transduction, ion transport, and antioxidant activities. Suppressed proteins belong to the following categories: oxidative phosphorylation pathway, photorespiration and protein translational machinery, oxidative stress, and ATPases. In the root, 106 protein spots changed significantly (P <0.05) after salt treatment, 63 spots were induced, and 43 suppressed by salt treatment. Salt induced proteins are associated with the following functional pathways: regeneration of S-adenosyl methionine, protein folding, selective ion transport, antioxidants and defense mechanism, signal transduction and gene expression regulation, and branched chain amino acid synthesis. Salt suppressed proteins are receptor kinase proteins, peroxidases and germin-like proteins, malate dehydrogenase, and glycine dehydrogenase. Based on the identified proteins, salt stress induced expression changes in different sets of proteins in leaf and root tissues. When compared in the context of metabolic pathways, branched-chain amino acid biosynthesis (ketol-acid reductoisomeras), glucose metabolism toward reducing glucose level, in addition to antioxidant, detoxification and selective ion uptake and transport, were induced in both root and leaves, which could be associated with salt tolerance of whole plant.