Abstract

Uncontrolled increase in population and pathogen resistance underscores the need to develop nutraceutical-rich plants that can serve as food and medicine. Heavy metal contamination remains a major impediment in achieving this goal. It was hypothesized that lysine could influence the metabolism of bitter melon (Momordica charantia L.) to enhance stress tolerance and nutraceutical quality. A pot experiment was conducted, where seeds of bitter melon were primed for 24 h with lysine (0, 0.01, 0.1 and 1 mM) and grown under cadmium (Cd) stress (control, 2 and 5 mg CdCl2/kg soil). Morphological traits, primary metabolites, antioxidants and antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa were analyzed. The fruit was evaluated for biomass, nutritional content and phenolic profile. Bitter melon showed inherent potential to inhibit both species. Stress reduced growth, chlorophyll, sugars and proteins contents, while phytate, hydrogen peroxide and malondialdehyde contents were increased. Lysine positively influenced all these attributes. Antibacterial activity against S. aureus was further improved in primed plants, with a positive correlation to nutritional parameters, peroxidase activity and the contents of flavonoids, p-coumaric acid, gallic acid, chlorogenic acid, quercetin, kaempferol and hydroxybenzoic acid. Therefore, lysine priming can be recommended as a safe and effective strategy to enhance the daily diet and improve production in Cd stress.