Stress-Responsive Metabolome Remodeling in Cynara cardunculus Calli
Cultivated cardoon ( Cynara cardunculus L. var. altilis ) is a Mediterranean food crop of the Asteraceae family that is well adapted to environmental stress. In this study, we aimed to uncover the features of biochemical adaptations by reducing plant complexity and employing cultivated cell cultures as a model system. We exposed cardoon calli to chilling and salinity. The results showed significant proline accumulation under both stress conditions, with upregulation of the Pyrroline-5-carboxylate synthase ( P5CS) and Pyrroline-5-carboxylate reductase ( P5CR) key genes, in proline biosynthesis. Oxidative damage was evident, as indicated by elevated H 2 O 2 levels, only at high doses and prolonged saline imposition. Enzymatic analysis of glucose-6-phosphate dehydrogenase (G6PDH) revealed metabolic reprogramming at the crossroads between primary and specialized metabolism in response to stress. GC-TOF-MS profiling identified 434 Differential Accumulated Metabolites (DAMs) upon stress, including organic acids, amino acids, sugars, alcohols, and polyphenols. A higher metabolic rearrangement was accompanied by increased levels of osmoprotectants such as organic acids (e.g., galactaric and galactonic acids) and amino acids (e.g., proline, phenylalanine, homoserine, and aspartate). Finally, we discuss our findings by focusing on how stress-induced metabolic reprogramming in cardoon calli, underpins the growth–defense trade-off and contributes to stress resilience.