Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
Metallomics. 2019 Mar 20;11(3):519-532. doi: 10.1039/c8mt00320c.
Arsenic (As), classified as a "metalloid" element, is well known for its carcinogenicity and other toxic effects to humans. Arsenic exposure in plants results in the alteration of the physiochemical and biological properties and consequently, loss of crop yield. Being a staple food for half of the world's population, the consumption of As-contaminated rice grain by humans may pose serious health issues and risks for food security. In this study, we have described the principal understanding of the molecular basis of arsenic toxicity and accumulation in plant parts. We described the measures for decreasing As accumulation in rice and understanding the mechanism and transport of As uptake, its transport from root to shoot to rice grain, its metabolism, detoxification, as well as the mechanisms lying behind its accumulation in rice grains. There are various checkpoints, such as the tuning of AsV/Pi specific Pi transporters, arsenate reductase, transporters that are involved in the efflux of As to either the vacuole or outside the cell, xylem loading, loading and unloading to the phloem, and transporters involved in the loading of As to grain, that can be targeted to reduce As accumulation in rice grain. Genes/proteins involved in As detoxification, particularly the glutathione (GSH) biosynthesis pathway, phytochelatin (PC) synthesis, and arsenic methyltransferase, also provide a great pool of pathways that can also be castellated for the low As in rice grains. Paddy rice is also used as fodder for animals, enhancing vacuolar sequestration and using constitutive promoters, which may be of concern for animal health. Therefore, using a root-specific promoter and/or converting inorganic arsenic into volatile organic arsenic might be a better strategy for low As in grain. Furthermore, in this review, the other specific approaches, such as bio-remediation, bio-augmentation practices, and molecular breeding, which have great potential to reduce As uptake from soil to rice grains, have also been highlighted.
砷（As）被归类为“类金属”元素，其致癌性和对人类的其他毒性作用是众所周知的。植物暴露于砷会改变其理化和生物学特性，从而导致作物产量下降。作为全球一半人口的主食，人类食用含砷的大米可能会对健康造成严重问题和食品安全风险。在本研究中，我们描述了砷对植物部分毒性和积累的分子基础的主要理解。我们描述了减少大米中砷积累的措施，以及理解砷吸收的机制和运输、砷从根部到茎部再到米粒的运输、代谢、解毒以及砷在米粒中积累的机制。存在各种检查点，例如调节 AsV/Pi 特异性 Pi 转运体、砷酸盐还原酶、参与将 As 排出液泡或细胞外的转运体、木质部装载、装载和卸载到韧皮部、以及参与将 As 装载到米粒的转运体，这些都可以作为靶点来减少大米中砷的积累。涉及砷解毒的基因/蛋白质，特别是谷胱甘肽（GSH）生物合成途径、植物螯合肽（PC）合成和砷甲基转移酶，也为降低大米中砷提供了很大的途径。水稻还被用作动物的饲料，增强液泡隔离和使用组成型启动子，这可能会对动物健康产生影响。因此，使用根特异性启动子和/或将无机砷转化为挥发性有机砷可能是降低谷物中砷的更好策略。此外，在本综述中，还强调了其他特定方法，如生物修复、生物增强实践和分子育种，这些方法具有很大的潜力，可以减少土壤到稻米中砷的吸收。
