Transcriptomic responses of Antarctic plants to in situ warming: uncovering molecular mechanisms behind physiological adjustments.

Abstract

Background and aims: Previous studies using open-topped chambers to simulate warming in Antarctic field conditions have shown distinct physiological responses between the two Antarctic vascular plants Colobanthus quitensis and Deschampsia antarctica. Colobanthus quitensis exhibited significantly increased photosynthetic capacity and growth during in situ warming conditions, whereas D. antarctica showed no differences in these parameters. To understand the differences in ecological strategies of these plants in response to climate change, it is important to elucidate the molecular mechanisms underlying physiological responses.

Methods: Transcriptome profiling was performed on plants from open-topped chambers and a control open area on King George Island, after three growing seasons. Differential gene expression was analysed using RNA sequencing, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses to identify key biological processes affected by in situ warming.

Key results: Colobanthus quitensis exhibited significant upregulation of photosynthesis-related genes, including aquaporins, carbonic anhydrases and Rubisco activase, enhancing CO2 diffusion and assimilation. Conversely, D. antarctica showed downregulation of photosynthetic pathways but upregulation of genes related to flowering, including flowering-promoting factor and phytochrome-regulatory proteins. Both species showed molecular signatures suggesting reduced freezing tolerance in warming conditions, potentially increasing their susceptibility to frost damage.

Conclusions: The results indicate distinct ecological strategies between the two plants in response to in situ warming. Colobanthus quitensis enhances its photosynthetic efficiency, whereas D. antarctica appears to accelerate its reproductive phase rather than focusing on growth. These findings contribute to our understanding of how Antarctic plants might respond to ongoing climate changes, with potential implications for their future resilience to extreme environmental conditions.