The Journey of Arsenic from Soil to Grain in Rice

Arsenic (As) is a non-essential toxic metalloid whose elevated concentration in rice grains is a serious issue both for rice yield and quality, and for human health. The rice-As interactions, hence, have been studied extensively in past few decades. A deep understanding of factors influencing As uptake and transport from soil to grains can be helpful to tackle this issue so as to minimize grain As levels. As uptake at the root surface by rice plants depends on factors like iron plaque and radial oxygen loss. There is involvement of a number of transporters viz., phosphate transporters and aquaglyceroporins in the uptake and transport of different As species and in the movement to subcellular compartments. These processes are also affected by sulfur availability and consequently on the level of thiol (-SH)-containing As binding peptides viz., glutathione (GSH) and phytochelatins (PCs). Further, the role of phloem in As movement to the grains is also suggested. This review presents a detailed map of journey of As from soil to the grains. The implications for the utilization of available knowledge in minimizing As in rice grains are presented

Biotechnological strategies for remediation of arsenic-contaminated soils to improve soil health and sustainable agriculture

Soil health is the foundation of sustainable agriculture, and its preservation is paramount in global arsenic (As) contamination challenges. Soil As contamination is a critical issue for environmental and agricultural sustainability. Rapid global urbanization and agricultural and industrial expansion release toxic metal (loid)s including As into the soil. Arsenic contamination disrupts the rhizosphere ecosystem, affecting plant health, microbial communities, and overall soil functionality. Ensuring soil health in the face of As contamination is imperative for human well-being and for developing a resilient, sustainable environment. This review signifies the need for comprehensive strategies to revitalize soil ecosystems, promoting resilience and long-term ecological balance. Advanced biotechnological approaches, particularly bioremediation including phytoremediation, microbial remediation, mycoremediation, nano-remediation, and other integrative strategies, are highlighted for their effectiveness in addressing As contamination and promoting soil health. Conventional physico-chemical techniques make soil unsuitable for agriculture by disrupting the microenvironment. Consequently, the urgent need for remediation of As-contaminated soil demands the adoption of eco-friendly and sustainable approaches, such as bioremediation, phytoremediation, and rhizoremediation, to enhance soil health.Development of transgenic lines and genetically modified organisms are effective tools in reducing the As burden. Bacteria including Sphingomonas desiccabilis, Bacillus subtilis and Bacillus idriensis expressing the arsM gene all show promising results to reduce the As burden. Transgenic rice, incorporating the arsM gene from Rhodopseudomonas palustris, demonstrated 10 times more volatile arsenicals and reduced As accumulation in the grain. Additionally, the use of As-hyperaccumulating plants and conventional methods, like chemical-assisted phytoextraction, show potential for decontaminating As- contaminated soil. Future research should explore the contributions of novel biotechnological strategies to enhance soil health in regions affected by As contamination