Application of nanoparticles for enhanced UV-B stress tolerance in plants

abstract: Ultraviolet-B radiation (UV-B) received at the Earth's surface has enhanced because of the declining level of ozone in the upper atmosphere. World-wide decline in crop yield is projected because of the harmful effect of UV-B. High UV-B level affects the growth of the plants by enhancing the concentration of reactive oxygen species (ROS), altering antioxidant enzyme activity, reducing photosynhetic rate, damaging DNA and cell membranes, and disrupting microtubule structure. Plants employ different mechanisms to resist UV-B stress, however these mechanisms collapse under high stress levels. Therefore, mitigation strategies are required to reduce the negative impacts of UV-B on plants. Nanotechnology, an emergent field of science, focusing on engineering of nanomaterial with approximately 1–100 nm size has application in different areas including enhancement of plant stress tolerance. Recent research on TiO2, Ag and Si nanoparticles (NPs) revealed that they can reduce UV-B stress in plants. NPs significantly alleviate UV-B stress by boosting photosynthesis, enhancing the accumulation of flavonoid, reducing oxidative stress by mimicking antioxidants or improving antioxidant enzyme activities and preventing the microtubule depolymerisation in plant cells. It was also found that effect of NPs was influenced by their physicochemical characteristics, concentration, exposure method, and level and duration of UV-B exposure. In this review, we present an up-to-date compilation of research on the impact of UV-B stress and its mitigation using NPs in plants. We have also discussed recent developments, existing research gaps and future prospects of NPs utilization for UV-B stress mitigation in plants.