Deciphering Cold Adaptation Mechanisms in Kobressia pygmaea: An Integrative Study Combining Multi-Temporal Physiological Profiling and Transcriptomic Analysis

Kobresia pygmaea is the dominant species in the alpine grasslands of the Qinghai-Tibet Plateau, playing a vital role in ecosystem stability due to its strong cold tolerance. However, the molecular mechanisms underlying its response to extreme low temperatures are still unclear.In this study, we systematically monitored the physiological responses of K. pygmaea under different temperatures (16 deg C, 4 deg C, 0 deg C, and -4 deg C) and time points (0-48 h), combined with transcriptome sequencing and weighted gene co-expression network analysis (WGCNA) to explore its cold stress regulatory network.The results showed that low temperature stress significantly increased the accumulation of proline and soluble sugars, enhanced antioxidant enzyme (SOD) activity, and raised malondialdehyde (MDA) content, indicating that K. pygmaea mitigates cold-induced damage through osmotic adjustment and antioxidant systems.Transcriptome analysis identified 4,174 differentially expressed genes (DEGs), with the greatest number of continuously responsive genes at -4 deg C, suggesting that extreme cold is the main driver of transcriptional changes.WGCNA revealed a core gene module (1,896 genes) sensitive to low temperature, enriched in pathways related to transcriptional regulation, DNA repair, protein processing, energy metabolism, and signal transduction. Further network and Venn analyses identified GGCT (FCM35_KLT17619) as a key gene consistently upregulated during cold stress, and qRT-PCR validated its expression trends.In summary, this study systematically reveals the physiological and molecular adaptation mechanisms of K. pygmaea to extreme cold temperatures, providing theoretical support and gene resources for molecular breeding and alpine ecosystem restoration.