Markers and Strategies for Biofortification Breeding in Wheat.

Markers and strategies for biofortification breeding in wheat Govindan Velu*, Ravi P. Singh and Yuanfeng Hao International Maize and Wheat Improvement Center (CIMMYT), Apdo Postal 6-641, Mexico DF 06600, Mexico *Email: velu@cgiar.org The world faces an unprecedented challenge of food and nutrition insecurity due to climate change and rapid population growth. About one-third of the world's population, especially women and children, mainly in developing countries suffer from deficiencies of essential micronutrients such as zinc (Zn) and iron (Fe). Breeding bread wheat varieties with increased levels of Zn and Fe in an adapted genetic background has the potential to alleviate micronutrient malnutrition of the world's most disadvantaged people where wheat serves as a major source of dietary energy. Germplasm screening of CIMMYT gene bank accessions revealed substantial genetic variation for grain Fe and Zn concentrations in the wheat progenitors such as Triticum dicoccoides, T. dicoccum, Aegilops tauschii and landraces originated from Iran were among the most promising sources of high Zn and Fe concentration. A targeted breeding program was initiated at ICIMMYT to develop wheat varieties with at least 8-12 mg/kg increased Zn over the popular varieties (25 mg/kg) with competitive yields and resistant to emerging strains of rusts including Ug99 races of stem rust. There has been continuous progress in terms of identifying competitive high-Zn candidate varieties in the target countries with the involvement of public and private sector partners. The proof-of-concept results from the performance of competitive biofortified high Zn wheat lines derived from these wide-crosses identified some of the landmark varieties which are being adapted by farmers in South Asia. Applying modern genomic tools and high throughput screening techniques would accelerate breeding efficiency to develop nutrient-rich wheat varieties. Two large effect QTLs were stably detected in chromosomes 2Bc (centromeric region) and 3AL for increasing grain Zn content in a RIL population derived from a cross ‘PBW343 x Kenya Swara’. The 2Bc QTL from PBW343 had pleiotropic effect; it significantly increased the thousand-kernel weight (TKW) and grain Zn. These promising QTLs are being validated in other mapping populations and in a diverse set of Association mapping panel. The 320 entries Association Mapping panel was phenotyped at multi-environments for grain Zn and Fe, and genotyped for 90K SNP using illumina platform. Interestingly, correlation between observed and genome-wide predicted values were greater than 0.50 for grain Zn and Fe in most of the environments indicates potential opportunity to apply genomic selection techniques to enhance grain Zn and Fe concentration in wheat.