The fern Nephrolepis exaltata is largely unresponsive to climate change conditions at both physiological and metabolic levels.

Climate change is impacting the performance of plants worldwide. However, the impact on ferns, the second-most diverse lineage of vascular plants, has received little attention. Here, we investigated the effects of one of the most claimed scenarios of the climatic change: drought (D), high temperature (HT) and high CO2 concentration (HCO2) on a fern (Nephrolepis exaltata) and a commonly studied angiosperm (Brassica oleracea) at photosynthetic, anatomical, and metabolic levels. Leaf anatomy was slightly affected by stress conditions in both species. Multivariate analysis demonstrated that B. oleracea's physiological responses to HCO2 were greater than N. exaltata's. Lipids and primary metabolites levels differed in response to stress in B. oleracea. Notably, the combination of D, HT, and HCO2 exacerbated the changes in primary metabolites, reducing amino and organic acids levels. Interestingly, phosphatidylcholine and phosphatidylethanolamine levels showed varied responses, increasing under HT and decreasing under HCO2 or combined stress in B. oleracea. In contrast, the fern was mostly unresponsive to D, HT, HCO2, and the combination among them at the metabolic level. Beyond providing important information concerning the trade-off between carbon uptake and stress acclimation mechanisms, our study indicates minor fern responses to D, HT, HCO2, suggesting differential impacts of climate change on ferns and angiosperms.