Adaptive Traits and Molecular Mechanisms of Rhododendron Species in Changbai Mountains' Alpine Tundra: A Phenotype-Transcriptome Study.

Alpine tundra's harsh conditions challenge plants, but Rhododendron's adaptive mechanisms remain unclear. This study explored phenotypic/transcriptomic adaptations of three Rhododendron species (R. aureum, R. lapponicum, R. redowskianum) in Changbai Mountains' tundra vs. timberline. Mature leaves were sampled for leaf length and leaf width measurement and RNA-seq. Results showed leaf width (not leaf length uniformly) reduced in tundra across all species. RNA-seq identified 2399-5716 DEGs per species; plant dwarfism DEGs (e.g., DELLA, EDS1) were up-regulated. Shared DEGs were enriched in carbon/nitrogen metabolism and stress response; IPUT1 (DUH022406.1) and PGT1 (DUH001929.1) were consistently down-regulated (linked to dwarfism). Species-specific responses included R. aureum's light adaptation, R. lapponicum's freezing/hypoxia response, and R. redowskianum's sugar/UV/microbial regulation. Rhododendron adapts to tundra via leaf width adjustment, metabolic optimization, and IPUT1/PGT1-mediated dwarfism, with conserved core mechanisms and species specialization, supporting climate change response predictions and conservation.