Genomewide Analysis for Elemental Concentration and ION Toxicity Tolerance in Wheat (Triticum aestivum L.) UNDER Waterlogging Stress.

Waterlogging impacts up to 25% of the worldwide area planted to wheat, including the southeastern region of the United States. Poor root development and decreased plant biomass, which collectively reduce wheat yield, are consequences of the energy crisis caused by oxygen depletion in waterlogged soils. Resistance to element toxicity is known to be an important adaptive trait contributing to waterlogging tolerance, as many microelements become more available for plant uptake when soils are saturated. This study aimed to determine the impact of elemental toxicity on the yield of soft red winter wheat and to identify resistant germplasm and quantitative trait loci that can be utilized for genetic improvement. 

            A 21-day field waterlogging treatment reduced the mean yield of 28 adapted wheat varieties by 42%, including significant reductions in total biomass and kernel weight spike^-1. Shoot concentrations of Zn, Cu, K and Mg decreased by 8% to 30% in waterlogged plants compared to control, while P, Ca, S, Na, Fe, Mn, and B increased by 13% to 455%. Mg, S, Na and Fe were negatively correlated with total yield, indicating that changes in concentration of these elements may limit yield in waterlogged soils.    

            An association mapping approach was used to identify potential markers and genes associated with elemental concentration under waterlogging using a panel of 240 wheat genotypes screened with 9K single nucleotide polymorphism (SNP) markers.  Overall, significant genetic variation was observed within the panel for all elements with the exception of boron, indicating genetic diversity for elemental accumulation. Population structure analysis showed unclear stratification and association analysis showed significant SNP-element associations on chromosomes 1A,1B, 2B, 2D, 3A, 3B, 5B, 6A and 7B. Analysis of potential candidate genes and markers within detected regions is ongoing.