Improving Rice Zinc Biofortification Success Rates Through Genetic and Crop Management Approaches in a Changing Environment

Abstract

Though rice is the predominant source of energy and micronutrients for more than half of the world population, it does not provide enough zinc (Zn) to match human nutritional requirements. Moreover, climate change, particularly rising atmospheric carbon dioxide concentration, reduces the grain Zn concentration. Therefore, rice biofortification has been recognized as a key target to increase the grain Zn concentration to address global Zn malnutrition. Major bottlenecks for Zn biofortification in rice are identified as low Zn uptake, transport and loading into the grain; however, environmental and genetic contributions to grain Zn accumulation in rice have not been fully explored. In this review, we critically analyze the key genetic, physiological and environmental factors that determine Zn uptake, transport and utilization in rice. We also explore the genetic diversity of rice germplasm to develop new genetic tools for Zn biofortification. Lastly, we discuss the strategic use of Zn fertilizer for developing biofortified rice.

Keywords: biofortification; endosperm; germplasm screening; physiological mechanisms; rice; zinc deficiency.

FIGURE 1

Mass flow of Zn - uptake and transport to loading into the rice grain. Different Zn transporters are involved in long distance transport and this flow differently regulated by Zn availability in soil and status in plants.

FIGURE 2

Different approaches to overcome dietary Zn deficiency: genetic biofortification through conventional breeding appeared to be sustainable and economically viable approach to overcome dietary Zn deficiency in global population. Blue color is used to indicate the authors’ preferred priorities for further biofortification work.