Mangroves are one of the most threatened ecosystems in the world. Climate change is projected to result in not only a poleward range shift in mangroves, but also mortality from higher intensity and frequency of extreme weather events (e.g. cold spell). Thus, the physiological and molecular adaptation of mangrove species to chilling stress is crucial to understanding their response to climate change, form effective management strategies, and conserve their long-term evolutionary potential. Here, we present a series of cold treatments that assessed the chilling stress response in key Asian mangrove species, including Bruguiera gymnorhiza, Avicennia marina, Rhizophora apiculata, Kandelia obovata and Kandelia candel. We compared the photochemical efficiency, enzyme activity, foliar phosphorus fractions and gene expression profiles throughout the cold treatment to determine the intra- and inter-specific latitudinal differentiation in chilling tolerance and to identify adaptive strategies that may lead to chilling tolerance. Our findings indicated that (1) the distributional range limits of tropical versus subtropical species were associated with adaptive differences in the regulation of photosynthesis under chilling stress; (2) adaptation to different temperature brackets contributed to geographic divergence and potentially speciation in mangroves, and (3) several strategies were involved in chilling tolerance, including efficient foliar phosphorus allocation and photoprotection. Collectively, these findings point toward the interactive effects among macroclimate, regulation of photosynthesis, nutrient enrichment, and stress adaptation in marginal populations of coastal plants.
Adaptive chilling stress response in Asian mangroves at latitudinal range limits