ABSTRACT
Heavy metal contamination in the soil has become a major threat to sustainable crop production. In recent era of urbanization, due to natural and anthropogenic activities, it has become a global concern as it directly affects the food chain. Plants with their intrinsic immobility are continuously exposed to various environmental stress factors along with heavy metal toxicity caused by industrial waste products, air and soil bourn chemicals, metal and metalloids which eventually induce cytotoxic and genotoxic stress to plants via the generation of reactive oxygen species (ROS) and their direct impact on genomic integrity. In response to this, plants need sophisticated adaptive mechanisms such as physiological, biochemical and molecular approaches to cope up with these environmental stress conditions without compromising their growth and development, reproductive success and eventually survival. These mechanisms require a complicated network to regulate gene expression at transcriptional and post-transcriptional levels including alteration of chromatin structure. Transcription factors (TFs) regulate the expression of various stress-responsive genes ensuring potential defence strategies in plants. TFs are often targeted by plant breeders for the development of stress-resistant transgenic plants. Transcription factor family like WRKY, basic leucine zipper (bZIP), basic helix loop helix (bHLH), MYB, ERFs are particularly involved in heavy metal homeostasis via regulating metal stress-responsive genes. Along with the transcriptional regulation, epigenetic modifications and their transgenerational segregation are also very crucial to maintain the plant genome stability and survival under such genotoxic stresses. In this present chapter, we have discussed our present understanding on the transcriptional and epigenetic regulations of plants in response to heavy metal toxicity and also emphasized the possible impact of the transgenerational stress response of epigenetic markers from parents to the next generation as one of the potential adaptive mechanism of survival under heavy metal stress in plants.
