Genetic Diversity and Genome-Wide Association Study in Grain Minerals of Synthetic Hexaploid Wheat for Genetic Biofortificaiton.

Nearly 800 million people are chronically undernourished and over two billion people suffer from micronutrient deficiencies. Wheat (Triticum aestivum L.) is a staple food for more than one third of the world population and its potential to assist in reducing micronutrient deficiencies can be achieved through integration of highly micronutrient rich wheat cultivars (genetic biofortification). Synthetic hexaploid wheat (SHW) (Triticum turgidum x Aegilopes tauschii) are being used as a means of introducing novel genes/genetic variation into bread wheat and potential source for high grain mineral concentrations. The objectives of the present study were to evaluate the genetic diversity of grain minerals within SHW germplasms, identify genomic regions contributing to higher mineral concentration, and develop molecular markers to transfer the useful alleles into high-yielding modern wheat germplasm. Grain mineral concentrations (B, Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, S, Se, Zn) were measured using an Agilent 7500cx inductively coupled plasma mass spectrometer in 126 SHW lines grown under drought stress in Konya, Turkey. Several synthetic lines greatly varied from the mean for grain mineral concentrations, such as Ca (64 to 195 mg Kg^-1), Cu (4 to 11 mg Kg^-1), Fe (21 to 63 mg Kg^-1), K (2551 to 6256 mg Kg^-1), Mg (892 to 1978 mg Kg^-1), Se (0.02 to 0.15 mg Kg^-1), and Zn (11 to 38 mg Kg^-1). The most outstanding SHW was AISBERG/AE.SQUARROSA (511), which has higher amount of useful minerals such as Ca (132 mg Kg-1), Cu (11 mg Kg^-1), Fe (60 mg kg^-1), K (5206 mg Kg^-1), Mg (1871 mg Kg^-1), and Zn (35 mg kg^-1). The 126 lines were also genotyped using genotype by sequencing and 37,592 high quality SNPs well distributed across the genome were identified. A genome-wide association study was conducted with different models that accounted for either just the kinship (K), or population structure (PCA or Q), or both (K+PCA, K+Q). Significant SNP-trait associations were detected for Ca, Fe, K, Ni, Se, and Zn and the number of significant SNPs per trait ranged from 1 to 36. These SNPs will be validated in a different population and will be converted to KASP markers that can be used in wheat breeding programs. In summary, these SHW lines are valuable sources for genetic biofortification of elite wheat germplasm and may help in reducing micronutrient deficiency.

Keywords: Micronutirent deficiency, KASP, SNPs, Kinship, Population structure