QTL mapping for grain zinc and iron concentrations and zinc efficiency in a tetraploid and hexaploid wheat mapping populations

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Official URL: http://dx.doi.org/10.1007/s11104-016-3025-8

Zinc (Zn) and iron (Fe) deficiencies are the most important forms of malnutrition globally, and caused mainly by low dietary intake. Wheat, a major staple food crop, is inherently low in these micronutrients. Identifying new QTLs for high grain Zn (GZn) and Fe (GFe) will contribute to improved micronutrient density in wheat grain. Using two recently developed RIL mapping populations derived from a wild progenitor of a tetraploid population "Saricanak98 x MM5/4" and an hexaploid population "Adana99 x 70,711", multi-locational field experiments were conducted over 2 years to identify genomic regions associated with high grain Zn (GZn) and grain Fe (GFe) concentrations. Additionally, a greenhouse experiment was conducted by growing the "Saricanak98 x MM5/4" population in a Zn-deficient calcareous soil to determine the markers involved in Zn efficiency (ZnEff) of the genotypes (expressed as the ratio of shoot dry weight under Zn deficiency to Zn fertilization) and its relation to GZn. The populations were genotyped by using DArT markers. Quantitative trait loci (QTL) for high GFe and GZn concentrations in wheat grains were mapped in the both RIL mapping populations. Two major QTLs for increasing GZn were stably detected on chromosomes 1B and 6B of the tetra- and hexaploid mapping populations, and a GZn QTL on chromosome 2B co-located with grain GFe, suggesting simultaneous improvement of GFe and GZn is possible. In the greenhouse experiment, the RILs exhibited substantial genotypic variation for Zn efficiency ratio, ranging from 31 % to 90 %. Two QTL for Zn efficiency were identified on chromosomes 6A and 6B. There was no association between Zn efficiency and grain Zn concentration among the genotypes. The results clearly show that Zn efficiency and Zn accumulation in grain are governed by different genetic mechanisms. Identification of some consistent genomic regions such as 1B and 6B across two different mapping populations suggest these genomic regions might be the useful regions for further marker development and use in biofortification breeding programs.