Table 3: Metabolites and hormones involved in plant responses to stress.

Stress Reference Abscisic acid, jasmonic acid, salicylic acid, polyamines, and others Drought, salinity, cold [3, 58, 65–67] Proline, glycine-betaine, and other compatible osmolytes Environmental stresses: drought, salinity, osmotic [62–64] Phytoalexins Microbial pathogens [89] Terpenes Toxins and pathogens [89] Phenolic compounds (coumarin, lignin, flavonoids, tannins, isoflavonoids) Pathogens, oxidative stress, UV light [89, 90] Alkaloids Pathogens (predators) [87] Unsaturated fatty acids Environmental stresses [73] ROS, malondialdehyde Biotic and abiotic stresses [3, 58, 68] Phytochelatins and metallothioneins Heavy metal intoxication [76, 77]