From apex to base: Uncovering spatial metabolic adaptation in Antarctic mosses

Abstract Antarctic mosses dominate the ice‐free terrestrial habitats of Antarctica, where survival requires tolerance to extreme environmental stress. While apical growth is active during short summer periods, the metabolic mechanisms supporting long‐term survival across vertically differentiated shoot zones remain poorly understood. Here, we examined the functional specialization of apical (zone 1), intermediate (zone 2), and basal (zone 3) tissues of Antarctic moss shoots using metabolomics. Shoots from three species ( Chorisodontium aciphyllum , Polytrichastrum alpinum , and Sanionia uncinata ) were sectioned into three zones and analyzed by ultra‐high performance liquid chromatography coupled with high‐resolution mass spectrometry. Fifteen biomarkers were quantified, including four targeted compounds: citric acid, zeaxanthin, violaxanthin, and adenosine monophosphate, selected for their roles in central energy metabolism and photoprotection. Lipid metabolism, antioxidant pathways, carbohydrate and galactose metabolism, and xanthophyll cycle pigments showed strong zone‐specific variations. Apical tissues were enriched in photoprotection and growth‐related metabolites; zone 2 accumulated stress signaling compounds; and zone 3, despite appearing biologically inactive, stored long‐term energy reserves and osmoprotective compounds critical for dormancy. These results demonstrate that Antarctic moss shoots are metabolically organized along the shoot axis, with long‐term persistence requiring the coordinated functioning of all three zones. In the absence of a vascular transport system, this spatial metabolic integration likely enables internal resource redistribution and coordinated stress protection, representing a key survival strategy for bryophytes enduring extreme polar environments.