Induction of Plant Defense Machinery Against Nanomaterials Exposure

Nanotechnology has the capability to play a crucial role in growth and crop production. Recently, the application of engineered nanoparticles has increased in the field of medical, consumer products, industrial, and agricultural activities. The application of nanostructured materials, designed for sustainable crop production, reduces nutrient losses, suppresses disease, and enhances yields. The literature indicates that the impact of nanomaterials (NMs) on plant growth, cell structure, and physiological and biochemical functions. NMs with a particle size < 100 nm influence key life events of plants, including seed germination, seedling vigor, root initiation, growth, and photosynthesis to flowering. Uptake, translocation, and accumulation of NMs by plants depend upon the features of NMs as well as the anatomy of the host plant. Additionally, NMs have been implicated in the protection of plants against oxidative stress as they mimic the role of antioxidative enzymes, such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX). However, besides their beneficial effects on plants, applications of NMs have been proven to be phytotoxic too as they enhance the generation of reactive oxygen species (ROS). The elevated level of ROS may damage the cellular membranes, proteins and nucleic acids. Therefore, with such a conflicting and ambiguous nature of NMs in plants, it is necessary to decipher the mechanism of cellular, biochemical, and molecular protection rendered by NMs under stressful environmental conditions. In this chapter, we discuss the induction of plant defense machinery against NMs. This review systematically summarizes and evaluates the current literature on nanoscale nutrients (metals, metal oxides, carbon) to enhance defense systems, growth, and yield in plants. Notably, this enhanced defense system may not only be directly linked to the reduced toxicity, but also to the potential nutritional value of the NPs themselves, especially for the essential micronutrients necessary for host defense. We also posit that these positive effects are likely a result of the greater availability of the nutrients in the “Nano” form. Last, we offer comments on the current regulatory perspective for such applications.