Dissecting Salt Stress-Induced Proteomic Changes in Pigeonpea (Cajanus cajan L. Millspaugh) Leaves: A Detailed Analysis of Stress-Responsive Protein Dynamics

Salinity is a major abiotic stress that poses significant challenges to global agriculture by reducing crop productivity and soil fertility. In pigeonpea (Cajanus cajan L. Millspaugh), comprehensive studies investigating proteomic responses to salt stress are limited. This study aims to establish a detailed proteomic profile for two pigeonpea varieties: ICPL 87119 (salt-tolerant) and ICPL 85063 (salt-sensitive) under NaCl-induced salt stress. The study evaluated the effects of different NaCl concentrations (0, 50 mM, 100 mM, 150 mM and 200 mM) on seedling growth including parameters such as plant height, fresh weight and leaf necrosis. Leaf protein profiles were analyzed using two-dimensional gel electrophoresis (2-DGE) to identify differentially expressed proteins under salt stress. Proteins from plants subjected to 150 mM NaCl stress were identified and characterized using MALDI-TOF-MS with a focus on proteins related to photosynthesis, ion transport and stress response mechanisms. Protein spots that exhibited differential expression were analyzed using PDQuest software. The results showed that salt stress significantly reduced plant growth and increased leaf necrosis, particularly at higher NaCl concentrations. Key proteins involved in photosynthesis such as the RuBisCO Large Subunit-Binding Protein Subunit Beta and ATP Synthase Subunit Beta, were differentially expressed. Proteins associated with ion transport, including the Glutamine Synthetase Leaf Isozyme and stress response proteins, such as Heat Shock Protein 7, also showed significant changes in expression. These findings highlight the critical roles of these proteins in the adaptive response of pigeonpea to salt stress. This study provides essential insights into the proteomic dynamics of pigeonpea under salinity, revealing key proteins and pathways involved in salt tolerance. The identified proteins represent potential targets for future research and biotechnological interventions to improve crop performance under adverse conditions.