Genomics Of Arsenic Stress Response In Plants

Heavy metal stress severely affects plant growth, development and reduces crop yield and productivity. Among different heavy metals, arsenic (As) is a toxic metalloid and a potent carcinogen. It not only hampers plant development but also causes severe health hazards to mankind once entered into the food chain. Infact, As contamination in the groundwater has turned out to be an epidemic in many regions of South and Southeast Asia. Naturally, As is present in trace amounts in the environment, however, geogenic sources and anthropogenic activities have tremendously increased the level of As in the soil. Epidemiological studies have reported that As poses severe health risk in humans. In plants, As affects several physiological and molecular processes, therefore, it is prerequisite to understand As uptake, translocation, accumulation and detoxification. As a part of detoxification mechanism, As undergoes chemical modifications including reduction, methylation, and glutathione conjugation. Alleviation of As phytotoxicity is important and attempts are being made in exploring the molecular components associated with As detoxification and tolerance in plants. In this context, it is important to understand the genetic control of As uptake and accumulation, which might help in protecting the food crops from contamination. In the past decade, significant knowledge has been generated at the level of "omics" which includes genomics, proteomics and metabolomics. Studies have demonstrated that plants' response to stress is associated with profound changes at the level of transcriptome. Modulation in the expression of genes involved in plants' stress response significantly assists in unravelling the pathways and networks providing tolerance towards stress. The information available through transcriptome studies led to the functional characterization of genes and development of plant varieties resistant to As stress. This chapter summarizes the current knowledge on As contamination, transcriptional regulation and biotechnological advances in the functional genomics of As uptake, transport, accumulation and detoxification in plants.