Advancing Zinc and Iron Biofortification in Wheat: Current Breeding Approaches and Future Prospects for Pakistan

Abstract

The micronutrient malnutrition is especially prevalent in Pakistan, of zinc (Zn) deficiency and iron (Fe) deficiency, as 97% of its population is dependent on wheat (Triticum aestivum L.) as calorie source. About 70 percent of soils in agriculture sector of Pakistan are low in plant available Zn. Soil micronutrient phytoavailability is significantly limited by highly calcareous and alkaline surface horizon of the Indus basin alluvium, enabling to directly pass on the soil micronutrient deficiencies to the food to be consumed by humans. By using landraces, wild relatives, and CIMMYT developed and supplied synthetic hexaploids and national partnerships, five biofortified cultivars have already been commercialized (Zincol-2016, Akbar-2019, Nawab-2021, Tarnab Rehbar, and Tarnab Gandum-I). Multiple markers assisted and genomic selection based introgression of micronutrient QTLs is possible without yield penalty, thanks to modern molecular frameworks to speed these fundamental improvements. At the same time, some new frontier biotechnologies like the overexpression of the NICOTIANAMINE SYNTHASE (NAS) gene or the suppression of phytic acid generation through a CRISPR/Cas9 approach provide solutions of major throw when the addressing plant nutrient bioavailability is concerned. The objective of high grain production and micronutrient density, as well as complicated genotype by environment (G × E) interactions driven by stress factors such as heat and drought, these are considerable challenges for the modern breeding. The use of saved seed from previous years is common. Overcoming these barriers will require speed breeding, high throughput phenotyping, and intensive testing in multiple environments to be integrated in a short time. Combining conventional, molecular, and biotechnological approaches to cultivate dual purpose crops capable of producing high biotic and abiotic stress tolerance contributes the most to managing systemic nutritional insecurity issues in Pakistan.

Full Text