Progress in breeding for trace minerals in staple crops.

Staples are not considered an important source of minerals in the diet. However, because of high staple consumption, any increase in mineral concentration might well have a significant effect on human nutrition and health. The nutritional quality of staple crops (rice, cassava, wheat, maize and beans) can be improved by breeding. Studies have shown the potential to exploit the genetic variation in seed concentration of iron and other minerals without the general negative effect on yield of adding new traits. The relationship between yield and mineral concentration may be positive, particularly in mineral-deficient soil. Initial evaluations have shown that some crop varieties have high Fe, Zn and carotene in their edible portions. The next step for conventional breeding will be to study the genetics of trace mineral inheritance to determine the best selection technique. Initial investigations of the genetics for high iron in rice have indicated a complex mode of inheritance, demonstrating additive and dominant gene and environmental effects. Breeding strategies have been developed based on these genetic findings. The use of biotechnological tools, such as molecular marker-assisted selection, will significantly increase the pace and prospects of success for breeding to improve the nutritional value of staple food crops.