Mineral nutrient acquisition, antioxidative defense, and metabolomic responses in divergent genotypes of Arachis hypogaea L. (peanut) for salinity resilience at early seedling stage.

Salinity is a major environmental stress affecting crop production, and understanding the molecular mechanisms of salinity tolerance is essential for improving crop resilience. The present study evaluates the salt resilience of two contrasting Arachis hypogaea (peanut) genotypes (GG7: fast growing and tall, TG26: slow growing and semi-dwarf) during the early seedling stage. The study focuses on mineral nutrient acquisition, antioxidative defense, and metabolomic responses. A comprehensive analysis involving two divergent genotypes (GG7 and TG26) of A. hypogaea subjected to three levels of salinity (50, 100, and 150 mM) revealed significant differences in their response to salt stress, highlighting the complex interplay between ion homeostasis, oxidative stress management, and metabolic adjustments. Salinity exposure led to altered ion profiles, with the tolerant genotype (TG26) demonstrating enhanced capacity for maintaining Na/K homeostasis and accumulating osmoprotectants, such as proline and sugars, to mitigate osmotic stress. The antioxidative defense system in TG26 genotype was more robust, showing increased activities of enzymes like superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX), which contributed to the scavenging of reactive oxygen species (ROS). The consistent level of malondialdehyde (MDA) under high salinity suggests that the TG26 seedlings are effectively protected against ROS due to the increased activity of antioxidant enzymes. Metabolomic profiling revealed differential accumulation of metabolites, including amino acids, organic acids, sugars and sugar alcohols, and phytohormones, which are critical for maintaining cellular integrity under salt stress. TG26 genotype exhibited higher accumulation of compatible solutes, such as sugars (pinitol, maltose, mannose, rhamnose, sucrose, glycerol, and xylitol) and amino acids (proline, alanine, cysteine, methionine, tyrosine, glycine, serine, leucine, valine, and phenylalanine). This increased accumulation may provide greater osmoprotection to TG26 compared to GG7 under high salinity conditions. Furthermore, the elevated levels of indole acetic acid (IAA), gibberellins (GA3), abscisic acid (ABA), and salicylic acid (SA) in TG26 genotype suggest their involvement in signaling pathways associated with salt adaptation and enhanced salinity tolerance. The findings underscore the importance of mineral nutrient acquisition and antioxidant mechanisms in conferring salinity tolerance in peanut. Additionally, the study emphasizes the potential for translational research to enhance salinity resilience in other crop plants by leveraging insights into the physiological and biochemical responses of A. hypogaea under saline conditions.