Proteome analysis of Indian seabuckthorn and detection of antifreeze proteins to understand the physiological adaptations under cold / freezing stress at different altitudes

Abstract

Since the last decade, our laboratory is trying to analyse and understand the stress modulatory path-ways in seabuckthorn deploying proteomics as a research approach. Initially, we deciphered the cold/freeze-modulated proteome in response to low temperature stress in laboratory grown seedlings by 1D and 2D gel-based LC/MS analysis. Currently, we are deciphering cold tolerance traits in naturally growing populations in the Himalayan range. A custom-built Proteome database was developed using label-free (nano LC-MS/MS) approach for annotation of proteins. We identified 4870 proteins, clustered into 1035 protein groups with expression of proteins associated with metabolic, regulatory, stress-responsive signaling path-ways in the Trans-Himalayan and Sikkim germplasm growing at different elevation. A comparative study utilizing both gel-free and gel-based proteomic approaches was conducted to analyze differential stress acclimation strategies in response to cold/freeze stress in both high-altitude Trans-Himalayan (H. rhamnoides, H. tibetana) and lower-altitude acclimated Sikkim (H. salicifolia) populations. These findings indicated differential regulation of antifreeze activity, metabolic path-ways, defense mechanisms, signal transduction, redox homeostasis, protein remodeling and secondary metabolite signatures. Further, metabolic profiling confirmed the proteome plasticity that confers distinct stress acclimation strategies. The Trans-Himalayan populations constrained their primary physiological attributes and allocated resources to endure harsh climatic conditions. While the Sikkim populations invested in growth-promoting path-ways. To the best of our knowledge, this is the first proteome study of naturally grown Indian seabuckthorn populations, indicating differential cold tolerance strategies at varied altitudes.