Biochemical aspects of aluminum tolerance in triticale (× Triticosecale Wittmack)

Aluminum (Al) toxicity severely restricts root growth and crop productivity in acidic soils. Despite the agronomic relevance of triticale (× Triticosecale Wittmack) in Europe, the biochemical basis of Al tolerance remains incompletely understood. Here, we combined physiological screening with multi-platform metabolite profiling and multivariate modeling to characterize Al-stress responses in highly homozygous triticale lines contrasting in Al tolerance (tolerant, T; non-tolerant, NT) and seasonal type (spring, S; winter, W). Al exposure induced pronounced shifts in biochemical composition, particularly in cell wall-associated carbohydrates and phenolic metabolites. NT lines accumulated higher levels of monosaccharides, arabinoxylan-derived fractions (based on arabinose and xylose measurements), and non-starch polysaccharides, alongside altered phenolic acid profiles. FTIR-based analyses revealed treatment- and genotype-dependent variation in glutathione (GSH), S-adenosyl-L-methionine (SAM), fatty acids (FA), and spectral signals associated with esterified polygalacturonic acid (PGA), with stronger genotype × treatment interactions for GSH and pectic components. Elastic Net regression identified carbohydrate composition, particularly the arabinose-to-xylose ratio, as a correlative indicator of Al treatment, suggesting stress-associated remodeling of arabinoxylan structure rather than a causal mechanism. In contrast, FTIR-based models more effectively resolved seasonal differences than Al treatment or tolerance classes, underscoring the dominant influence of developmental background on spectral profiles. Mixed graphical models further indicated that Al treatment primarily structured metabolic associations, whereas seasonality shaped redox- and energy-related interaction networks. Overall, our results reveal coordinated, genotype-dependent biochemical reprogramming under Al stress, highlighting distinct contributions of cell wall carbohydrate remodeling and metabolic network reorganization in triticale responses.