Increasing temperatures and CO2 impact on primary and specialized metabolism of Brassica species

Rising atmospheric CO2 levels are driving climate change, increasing temperatures, and impacting plant metabolism. In this study, we analyzed the effect of high CO2 concentrations (eCO2) and elevated temperatures on primary and specialized metabolism in two Brassica oleracea genotypes: a wild-type accession (Winspit) and a commercial variety (Parthenon). Metabolic profiling revealed common patterns of changes in several primary metabolites, including amino acids (glutamate, aspartate) and organic acids (citrate, glycerate, ascorbate), under high temperature and/or eCO₂. Interestingly, these changes were organ-specific. In shoots, aspartate and glutamate decreased under elevated temperature when combined with eCO₂, while in roots, their levels increased. Citrate increased in roots of both genotypes under high temperatures, but decreased in shoots. However, ascorbate levels dropped in roots and rose in shoots under combined stress.Glucosinolate content and profiles also showed consistent yet organ-dependent responses. The increase in CO2 and temperature had a greater effect on total glucosinolate content in roots compared to shoots, particularly due to the increase in indolic glucosinolates, while aliphatic glucosinolates mainly increased in shoots. This led to a decreased aliphatic/indolic glucosinolates ratio in roots. As a consequence of alterations in primary and specialized metabolites, nitrogen and sulfur homeostasis were also disrupted. Our findings highlight that plant acclimation to eCO2 and temperatures is highly coordinated, involving primary and specialized metabolism at the whole-plant level, and that not only genotype or environmental specific changes but also organ specific patterns of response must be considered.