Proteomic analysis of salt stress responses in foxtail millet ( Setaria italica L. cv. Prasad) seedlings

Abstract

Soil salinity is one of the major abiotic stresses limiting crop productivity and the geographical distribution of many important crops worldwide. To gain a better understanding of the salinity stress responses at molecular level in dry land small millet crop, foxtail millet ( Setaria italica L.), we carried out a comparative proteomic analysis. Foxtail millet seeds were surface sterilized and germinated in Petri plates lined with filter paper. Salt stress was imposed by serving the Hoagland half strength nutrient solution with 100, 150 and 200 mM NaCl (saline treatment) or without (control) and maintained in dark for 7 days. Salt treatment resulted in reduced seedling growth and dry mass. The temporal changes in total protein profile of foxtail millet seedlings under different salt stress regimes were studied using two-dimensional electrophoresis. Among ∼175 protein spots reproducibly detected on each gel, some were up-regulated and few others were down-regulated at least at one time point. Mass spectrometry analysis allowed the identification of 29 differentially expressed proteins including well-known salt responsive proteins. Several proteins showed up- and down-regulation during salt stress. MALDI-TOF/MS analysis and database searching of some of the identified proteins indicated that the proteins are known to be involved in several processes, i.e., of signal transduction, photosynthesis, cell wall biogenesis, stress related and several metabolisms like energy, lipid, nitrogen, carbohydrate and nucleotide metabolisms, where others are of unknown function. In conclusion, our study provides new insights into salt stress responses in foxtail millet and demonstrates the advantages of proteomic analysis.