Environmental factors can impact the secondary metabolites in plants under climate change: a focus on UV-B stress

Different environmental stressors, including ultraviolet (UV) stress, can lead to significant changes in gene expression, metabolism, secondary metabolites, plant height, growth and development, as well as overall plant yield. UV radiation, which ranges from 100 nm to 400 nm, does not participate in photosynthesis and is divided into three categories: UV-A (315–400 nm), UV-B (280–315 nm), and UV-C (100–280 nm). Among these, UV-A is the least harmful to living organisms due to its lower energy and capability to penetrate the ozone layer. In contrast, UV-C is highly damaging but is fortunately absorbed by the atmosphere. UV-B, however, can be harmful to all forms of life at high concentrations. To combat UV stress, plants employ various defense strategies, including thickening their leaves, boosting flavonoid production, and regulating antioxidant levels. UV-B stress also alters the fatty acid profiles in oilseed plants, increasing the levels of palmitic and oleic acids. Exposure to intense UV-B can result in abnormal growth patterns and significant reductions in plant yield. The harmful impacts of UV-B exposure include the suppression of photosystem II (PSII), disruption of electron transport mechanisms, decreased photosynthesis rates, and damage to nucleic acids, membrane lipids, proteins, and photosynthetic pigments. These adverse effects culminate in reduced biomass accumulation, altered nutrient allocation, hindered cell development, and ultimately diminished crop yields.