Transcriptome Analysis Reveals the Genetic Basis of Phenotypic Traits of Vaccinium uliginosum L. at Different Elevations in the Changbai Mountains

The morphological traits of Vaccinium uliginosum L., including plant height, leaf area, and fruit weight, have changed significantly across an elevational gradient in the Changbai Mountains. To elucidate the molecular mechanisms underlying these morphological variations, RNA-Seq technology was employed to identify differentially expressed genes (DEGs), key metabolic pathways, and associated biological functions of V. uliginosum at seven elevations in the Changbai Mountains. A total of 1190 DEGs significantly associated with morphological variations were identified. These genes are mainly involved in lipid synthesis, carbohydrate metabolism, energy metabolism, and signal transduction. Redundancy analysis (RDA) revealed that fatty acyl-ACP thioesterase B (FATB) and ribulose-bisphosphate carboxylase small subunit (cbbS) exhibited a significant association with morphological variation. Integrated analysis indicated that high-altitude plants likely enhance lipid synthesis and cell wall stability while also inhibiting photosynthesis and carbohydrate metabolism. The regulatory mechanisms underlying hormone signal transduction may be relatively complex, as evidenced by the enhanced activity of gibberellin and reduced biological effects of auxin, abscisic acid, and ethylene. This study is the first to provide transcriptomic evidence elucidating the genetic basis of altitudinal morphological adaptation in V. uliginosum, integrating phenotypic traits with gene expression profiles across an elevational gradient.