Mechanistic approaches for crosstalk between nanomaterials and plants: plant immunomodulation, defense mechanisms, stress resilience, toxicity, and perspectives

Abstract

Plants are challenged with unexpected and diverse environmental stresses in the era of climate changes. Plant development and metabolism are significantly hindered by both abiotic and biotic stresses, which lead to a reduction in the crop yield by 50–88% worldwide. Fortunately, plants have developed diverse defence mechanisms across multiple levels in response to environmental challenges. Plant defence mechanisms range from molecular-level modifications to morphological, physiological, anatomical, and biochemical characteristics. In addition, nanotechnology is a promising area of innovations in the field of plant sciences, and it is generating novel concepts for comprehending the optimal survival mechanism of stressed plants. Nanomaterials are considered regulatory molecules for plants owing to their ability to modulate an extensive array of physiological and biochemical processes, the plant immune system, stress-related gene expression, hormonal regulation, and the activation of anti-oxidative defence systems. However, the intricacies of interactions between nanomaterials and plants in terms of antioxidative and immunomodulatory effects are not yet fully explored. Thus, the present review elucidates the potential antioxidative and immunomodulatory regulation of nanomaterials in plants via an enhanced antioxidative system, reduced oxidative stress levels and reactive oxygen species (ROS) generation, upregulation of defense related gene expression, phytohormone regulation, and miRNA regulation. Further, the toxicity behaviour of nanomaterials in plants and developmental prospects are discussed to provide future directions in the area. Overall, this review provides new insights for the development of nanomaterials with potential immunomodulatory effects in plants for resistance against biotic and abiotic stresses.