The Effect of Ploidy on the Concentration of Soluble Sugars in Wheat Seeds– Exploring the Metabolome of Afghan Wheat Landraces

Background: Cultivated wheat exists in two ploidies: allotetraploid pasta wheat and allohexaploid bread wheat. Ploidy is known to modify plant metabolism, yet studies comparing metabolomic profiles of allotetraploid and allohexaploid wheat are scarce. Objective: To characterize the ploidy and metabolomic profiles of selected Afghan wheat landraces collected in the 1960’s and preserved in Japan and elite wheat cultivars. Methods: Ploidy was determined in cell nuclei of wheat seedlings using flow cytometry. Metabolic profiles of polar compounds were obtained with 1H NMR. Metabolite identification was performed with 2D NMR and comparison against databases. Results: We identified allotetraploid and allohexaploid variants of wheat landraces collected in Afghanistan half a century ago. 1H NMR metabolomics discovered a separation between the allotetraploid and allohexaploid metabolic profiles. 2D NMR based compound identification showed that the most variable metabolites were low molecular weight sugars, compounds that were more abundant in seeds of allotetraploid wheats. Conclusion: We discovered a correlation between ploidy and metabolomic profiles with higher concentrations of soluble sugars in allotetraploid wheat. Keywords: Flow cytometry, NMR, landrace, metabolomics, ploidy, wheat.