Plant Nutrition for Human Nutrition: Hints from Rice Research and Future Perspectives

Both plants and humans require mineral elements for their healthy growth and development. Mineral elements in the soil are taken up by the plant roots and transported to the edible parts for human consumption through various different transporters. An ideal future crop for human health should be rich in essential mineral elements but with less toxic elements in the edible parts. However, due to the great difference in the numbers and amounts of mineral elements required between plants and humans, it is a challenge to balance plant growth and nutrient requirement for humans. In this article, we mainly focus on the transport system of mineral elements from soil to grain in rice, a staple food for half of the world's population, and discuss recent progress on the underlying genetic and physiological mechanisms. Examples are given for silicon, zinc, and iron essential/beneficial for both plants and humans, selenium and iodine only essential for humans, and toxic cadmium and arsenic for all organisms. Manipulation of some transporters for these elements, especially those localized in the node for allocation of mineral elements to the grain, has been successful in generating rice with higher density and bioavailability of essential elements but with less accumulation of toxic elements. We provide our perspectives toward breeding future crops for human health.