ABSTRACT
Plants produce numerous secondary metabolites in response to various stimuli. Humans have used plants to develop active ingredients of medicines, nutraceutical products, insecticides, herbicide, or dyes, among other products. Most of the environmental factors, such as dryland or pollution, may produce stress in plants inducing the production of reactive oxygen species and, in response, the plant triggers a protective effect that promotes the biosynthesis of secondary metabolites. The amount and type of secondary metabolites synthesized by plants depends on the genetic variability and plasticity of the phenotypes; however, this can vary drastically depending on the species, organ, tissue, stage of development, and environmental conditions. During the past few decades, anthropocentric activity has caused a considerable increase in pollution, among the most characterized are pesticides and heavy metals in the air, soil, or water; therefore, contamination by persistent pollutants allows plants to be exposed for long periods of time and increases the probability that these compounds will be assimilated by plants and bioaccumulate in different plant structures, affecting the quality of secondary metabolites produced.
