Comparison of the protein system in early response to salinity stress of three rice varieties (Oryza sativa L.) with contrast phenotypes

Rice (Oryza sativa L.), a staple food for over 40 % of the global population, faces significant yield losses due to salinity stress, particularly at the germination stage. This study compared early proteomic responses to NaCl stress in three Vietnamese rice varieties with contrasting tolerance: OM 9577 (salt-tolerant), OC 10 (moderately tolerant) and Dai Thom 8 (salt-sensitive). Germinating seeds were subjected to NaCl treatment and proteins were extracted for analysis by Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) and Two-Dimensional gel Electrophoresis (2-DE) combined with LC-MS/MS. In total, 160 peptide fragments corresponding to 45 differentially abundant proteins were identified, spanning 13 functional categories, including metabolism, stress response, transcriptional regulation, signal transduction, cellular transportation, cell growth, cell division and protein modification. 2-DE profiles confirmed characteristic proteins in the tolerant and moderately tolerant varieties: OC 10 exhibited three proteins associated with cellular transportation, stress response, signal transduction and transcription, while OM 9577 exhibited eight proteins related to nucleotide metabolism, transport, signal transduction, stress response, cell growth, cell division and transcriptional regulation. These proteins likely underline enhanced salt tolerance and are proposed as candidate biomarkers for molecular screening and the improvement of salt-tolerant rice via conventional breeding and gene transfer.