Identification of proteins in response to terminal drought stress in sorghum (Sorghum bicolor (L.) Moench) using two-dimensional gel-electrophoresis and MALDI-TOF-TOF MS/MS

Abstract

Terminal drought responses in sorghum (Sorghum bicolor (L.) Moench) leaf tissue (Btx642) was investigated under post-flowering drought stress. Phenotypic data measurements and changes in protein abundance were compared between observed mean values of traits and protein spots of the well-watered (control) and drought stressed plants. Protein separation of the replicated tissue was conducted using two-dimensional gel electrophoresis. Gels were stained using Coomassie Brilliant Blue and then scanned by Molecular Imager PharosFX Plus System (BIO-RAD). Sixteen spots among 86 produced were selected based on intensity or abundance and resolution for protein identification using Matrix Assisted Laser Desorption/Ionisation—time of flight mass spectrometry (MALDI-TOF-TOF MS/MS). Nine proteins with 6 functional categories and 3 subcellular localization were identified based on MASCOT search engine of which 77.7% were significantly expressed. This study, show how plants induce intracellular signals to activate drought-response and defense pathways by up-regulating key proteins and also bypass stress condition by down regulating the rate limiting enzymes. The key metabolic pathways involved in the drought stress response were shown with 5 functional classes. The findings demonstrate novel functions of the proteins with central role in maintaining intact metabolic and photosynthetic pathways in sorghum under drought stress. Our work provides initial information as the basis for modern breeding to enhance drought tolerance and productivity in sorghum.