Proteomics approach to understanding salt stress response in halophytic wild rice species

Abstract:

Interest in halophytic wild rice relatives as genetic resources for salt tolerance has grown sharply over the past decade, yet the proteomic basis of their salt-adaptive mechanisms remains poorly mapped. This research used two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) coupled with MALDI-TOF/TOF mass spectrometry to identify differentially expressed proteins in the halophytic species Oryza coarctata under 150 mM NaCl stress for 72 hours, compared with the salt-sensitive cultivar IR29. Experiments were conducted at the Plant Biotechnology Laboratory, Siberian Agricultural College, Omsk, from January to August 2023. Leaf and root proteomes were analysed separately. A total of 87 differentially expressed protein spots (≥ 2-fold change, p<0.05) were detected in O. coarctata, of which 52 were successfully identified by mass spectrometry. These proteins grouped into five functional categories: antioxidant defence (23.1%), signal transduction (19.2%), ion transport (17.3%), osmotic adjustment (21.2%), and structural maintenance (19.2%). Key salt-responsive proteins included superoxide dismutase (SOD, 4.7-fold up), vacuolar H⁺-ATPase (3.8-fold), and late embryogenesis abundant (LEA) protein (5.1-fold). The cultivated line IR29 showed fewer differentially expressed spots (41) and lower fold changes. These findings highlight candidate proteins for marker-assisted introgression of salt tolerance from O. coarctata into cultivated rice.