REVIEW: Biofortification of Durum Wheat with Zinc and Iron

Abstract

Micronutrient malnutrition affects over 2 billion people in the developing world. Iron (Fe) deficiency alone affects >47% of all preschool aged children globally, often leading to impaired physical growth, mental development, and learning capacity. Zinc (Zn) deficiency, like iron, is thought to affect billions of people, hampering growth and development, and destroying immune systems. In many micronutrient‐deficient regions, wheat is the dominant staple food making up >50% of the diet. Biofortification, or harnessing the powers of plant breeding to improve the nutritional quality of foods, is a new approach being used to improve the nutrient content of a variety of staple crops. Durum wheat in particular has been quite responsive to breeding for nutritional quality by making full use of the genetic diversity of Fe and Zn concentrations in wild and synthetic parents. Micronutrient concentration and genetic diversity has been well explored under the HarvestPlus biofortification research program, and very positive associations have been confirmed between grain concentrations of protein, Zn, and Fe. Yet some work remains to adequately explain genetic control and molecular mechanisms affecting the accumulation of Zn and Fe in grain. Further, evidence suggests that nitrogen (N) nutritional status of plants can have a positive impact on root uptake and the deposition of micronutrients in seed. Extensive research has been completed on the role of Zn fertilizers in increasing the Zn density of grain, suggesting that where fertilizers are available, making full use of Zn fertilizers can provide an immediate and effective option to increase grain Zn concentration, and productivity in particular, under soil conditions with severe Zn deficiency.

Hydrolysed wool: a novel soil amendment for zinc and iron biofortification of wheat

“…In our study, WH application resulted in a higher grain protein concentration, which correlated positively with Zn and Fe grain concentration. As in the study of Cakmak et al (2010), grain proteins could represent a sink for Zn and Fe. A further benefit of the high grain protein concentrations is that it could contribute to higher bioavailability of micronutrients in the diet, as shown by House et al (1996) and Lo¨nnerdal (2000).…”

“…Nitrogen application and N availability also positively affects wheat grain protein concentration (Dupont et al 2006). Cakmak et al (2010) found that grain Zn and Fe concentrations were strongly correlated with grain protein. Very low levels of grain protein have been suggested as a major reason for low concentrations of Zn and Fe in grains.…”

Nutritionally Enhanced Staple Food Crops

“…In addition to the physiological mechanisms involved in the uptake, distribution, and accumulation of Fe and Zn in seed (Borg et al 2009;Cakmak et al 2010), the use of genes (L€ onnerdal 2003;Vasconcelos et al 2003;Ghandilyan et al 2006;Brinch-Pedersen et al 2007;Waters et al 2009;Sperotto et al 2010), and chelating agents such as EDTA (Nowack et al 2008) have been reported to enhance efflux of nutrients including Fe and Zn from the vegetative tissues to seed of crops.…”

Strategies to increase zinc deficiency tolerance and homeostasis in plants

“…Some enzymes, such as alcohol dehydrogenase, Cu-Zn superoxide dismutase, and carbonic anhydrase, have zinc in their structure. Other enzymes, such as aldolases, enolase, isomerases, peptidases, transfosforylases and RNA and DNA polymerases, require zinc for enzymatic activity (Welch and Grahan, 2004;Cakmak et al, 2010). According to the World Health Organization (2003), zinc deficiency in humans can result in several undesirable consequences, including diminished learning ability, impaired immune response, dysfunction of reproductive system, and reduced growth rates on infants.…”