From paddy soil to dining table: biological biofortification of rice with zinc.

One-third of paddy soils are globally deficient in zinc (Zn) and 40% of Zn loss in the procession from brown rice to polished rice, which results in the global issue of hidden hunger, e.g., the micronutrient deficiencies in the rice-based population of developing countries. In the recent decades, biofortification of cereal food crops with Zn has emerged as a promising solution. Herein, we comprehensively reviewed the entire process of Zn in paddy soil to human diet, including the regulatory mechanism underlying Zn absorption, transport, distribution, and accumulation in rice grain. Moreover, biofortification approaches of Zn have been summarized in conventional breeding, genetic engineering, agronomic management, and seed priming. Meanwhile, entire process and key nodes from paddy soil to human diet consumption were highlighted. Finally, future directions and challenges of Zn biofortification in rice were proposed. These comprehensive results show the great promise for addressing Zn deficiency and promoting the human nutrition.