How do some plants tolerate low levels of soil zinc? Mechanisms of zinc efficiency in crop plants.

Researchers are beginning to understand how some plant genotypes can maintain reasonable growth and yields under low soil Zn, a trait termed zinc efficiency (ZE). Several studies have shown no correlation between ZE and root Zn uptake, Zn translocation to shoot, or shoot Zn accumulation. Furthermore, it has not been possible to conclusively link differences in leaf subcellular Zn compartmentation with ZE. However, biochemical Zn utilization, including the ability to maintain the activity of Zn requiring enzymes in response to Zn deficiency may be a key component of ZE. The next logical step in investigations of this trait is research on the genetic and molecular basis for ZE, in order to better understand the relationship between Zn utilization and ZE, and to identify the gene(s) controlling ZE. Progress in this research area could provide the knowledge to facilitate the engineering of Zn-efficient plant varieties, which could help both crop production on marginal soils as well as possibly improve the micronutrient density of food crops to help address significant human nutrition problems related to micronutrient deficiency.