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

Background And Aims: Previous studies using open-top chambers to simulate warming in Antarctic field conditions have shown distinct physiological responses between the two Antarctic vascular plants Colobanthus quitensis and Deschampsia antarctica. While C. quitensis exhibited significantly increased photosynthetic capacity and growth under in situ warming conditions, 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-top chambers and control open area on King George Island, after three growing seasons. Differential gene expression was analyzed using RNA sequencing, followed by Gene Ontology and KEGG pathway enrichment analyses to identify key biological processes affected by in situ warming.

Key Results: C. 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 photosynthesis 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 under warming conditions, potentially increasing their susceptibility to frost damage.

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