Transcriptome analysis unveils the intricate dynamics of senescence responses in Himalayan treeline species, Betula...

High-altitude ecosystems in the Himalayas exhibit extreme seasonal variations in their vegetation, with summer and winter presenting the most pronounced environmental contrasts. As winter progresses, temperatures drop, and deciduous plant species undergo senescence. This study unravels the transcriptomic dynamics driving leaf senescence in Himalayan treeline species, Betula utilis, during seasonal variations. Using the RNA-sequence technology, leaf samples collected under fresh and senescent stages were analysed to deduce expression profiles at different stages. A total of 6505 differentially expressed transcripts were identified, with functional annotations revealing key senescence pathways such as phytohormonal regulation, chlorophyll degradation, and nutrient remobilisation. The upregulation of senescence-associated genes (SAGs), alongside alterations in transcription factors like WRKY and hormonal pathways, highlights the molecular interplay driving seasonal adaptation. Additionally, chlorophyll catabolism, modulated by NYC1 and PAO, was observed as a pivotal response to winter conditions. The findings of the study provide insights into the importance of carbohydrate metabolism, hormonal signalling, and stress adaptation-related pathways in nutrient conservation and plant fitness under environmental stress. This study offers a comprehensive understanding of the genetic mechanisms that allow B. utilis to withstand the harsh Himalayan climate, adding invaluable information to the fields of plant senescence, stress physiology, and climate resilience.