Integrated physiological and comparative proteomics analysis of contrasting genotypes of pearl millet reveals underlying salt‐responsive mechanisms

Abstract

Salinity stress poses a significant risk to plant development and agricultural yield. Therefore, elucidation of stress‐response mechanisms has become essential to identify salt‐tolerance genes in plants. In the present study, two genotypes of pearl millet (Pennisetum glaucum L.) with contrasting tolerance for salinity exhibited differential morpho‐physiological and proteomic responses under 150 mM NaCl. The genotype IC 325825 was shown to withstand the stress better than IP 17224. The salt‐tolerance potential of IC 325825 was associated with its ability to maintain intracellular osmotic, ionic, and redox homeostasis and membrane integrity under stress. The IC 325825 genotype exhibited a higher abundance of C4 photosynthesis enzymes, efficient enzymatic and non‐enzymatic antioxidant system, and lower Na+/K+ ratio compared with IP 17224. Comparative proteomics analysis revealed greater metabolic perturbation in IP 17224 under salinity, in contrast to IC 325825 that harbored pro‐active stress‐responsive machinery, allowing its survival and better adaptability under salt stress. The differentially abundant proteins were in silico characterized for their functions, subcellular‐localization, associated pathways, and protein–protein interaction. These proteins were mainly involved in photosynthesis/response to light stimulus, carbohydrate and energy metabolism, and stress responses. Proteomics data were validated through expression profiling of the selected genes, revealing a poor correlation between protein abundance and their relative transcript levels. This study has provided novel insights into salt adaptive mechanisms in P. glaucum, demonstrating the power of proteomics‐based approaches. The critical proteins identified in the present study could be further explored as potential objects for engineering stress tolerance in salt‐sensitive major crops.

Molecular insights into the salt stress response of Pearl millet (Pennisetum glaucum): Pathways, differentially expressed genes and transcription factors

“…Its genome encodes a vast array of genes and pathways that control diverse aspects of plant growth, development and environmental cue response. When exposed to excessive levels of salt in the soil, Pearl millet activates multiple stress‐response and physiological maintenance pathways (Jha et al, 2022). The physiological function that is maintained through the upregulation or downregulation of multiple genes involved in essential pathways.…”

Deciphering trait associated morpho-physiological responses in pearlmillet hybrids and inbred lines under salt stress

“…Recently, putative WRKY protein factors have been identified in pearl millet in response to both dehydration and salinity stress involved in tolerance mechanisms (Chanwala et al, 2020). Upregulation of salt-induced proteins impart salt tolerance in tolerant pearl millet accessions with reduced expression in the sensitive accessions (Jha et al, 2022). Further, the sugars get accumulated under abiotic stress conditions due to decreased rate of respiration as well as down regulation of glycolysis (Nguyen et al, 2010).With increasing salinity stress, protective soluble proteins are synthesized de novo or may be present inheritably (Soni et al, 2020).…”

Salt stress proteins in plants: An overview

“…This specific network of metabolic pathways can be used as salt stress imprints (Cheng et al, 2014). Such changes in metabolism are due to salt stress sensor proteins and metabolic biosynthesis enzymes directly involved in the acquisition of salinity tolerance (Hey et al, 2009;Barajas-Lopez et al, 2018;Yang et al, 2019;Jha et al, 2022).…”