Intrinsic and induced metabolic signatures underpin aluminum tolerance in bread wheat: a comparative metabolomics approach

Abstract

Aluminum (Al) toxicity is a major impediment to plant growth and yield in low pH soils. Exclusion and/or vacuolar sequestration of Al with organic acids and phenolic compounds is the primary tolerance mechanism utilized by plants to mitigate Al toxicity. However, little is known about the intrinsic and Al-induced metabolic differences underlying intraspecific variability in tolerance to Al toxicity. To fill this gap, we determined root metabolic profiles of Al-sensitive (Golia-99) and Al-tolerant (Demir-2000) bread wheat cultivars treated with 0, 10, and 30 mu M AlCl36H2O using nuclear magnetic resonance (NMR) spectroscopy. Our results showed that there were marked differences in the concentrations of numerous metabolites between Golia-99 and Demir-2000 roots under both control and Al stress conditions. In this regard, a number of metabolites from the amino acid and TCA groups, such as citrate, cysteine, glutamate, isocitrate, phenylalanine, and succinate, were found to be intrinsically higher levels in Demir-2000 than in Golia-99. In addition, Al toxicity led to the accumulation of asparagine, glutamine, putrescine, pyroglutamate, and soluble sugars in Demir-2000 roots. Furthermore, Al treatments significantly altered many metabolic pathways in both cultivar-specific and cultivar-independent manners. The major pathways contributing to the difference in Al toxicity tolerance between Demir-2000 and Golia-99 were arginine biosynthesis, glycolysis/gluconeogenesis, and the metabolisms of cysteine and methionine, glutathione, glycine, serine and threonine, pyruvate, sulfur, and tyrosine. Overall, our results suggest that the distinct patterns of Al-induced overrepresentation in amino acid, carbohydrate, and energy metabolism play an important role in explaining the differential tolerance capacities of Demir-2000 and Golia-99 to Al toxicity. The outcomes of this study may provide valuable insights into improving Al tolerance in wheat through breeding and genetic engineering.