Selection and Validation of Stable Reference Genes for RT-qPCR Analyses of (Polygonaceae) Under Four Abiotic Stresses.

: (Polygonaceae), a perennial herbaceous species predominantly found in northern temperate regions, has been historically utilized in traditional Chinese medicine for its hematological regulatory properties, including blood cooling, hemostasis, and detoxification. Despite the pharmacological value of this species, unvalidated reference genes compromise precise gene expression profiling. : We initially selected eight candidate genes (, , , , , , , ) from transcriptomes and then assessed their transcriptional stability using RT-qPCR across root, stem, and leaf tissues under four abiotic stresses: cold, drought, salinity, and heavy metal exposure. : emerged as the most stable reference gene in three specific scenarios: root/leaf tissues under cold stress, stems during drought exposure, and roots subjected to salt treatment, revealing distinct tissue-stress response patterns. emerged as the most stable reference in cold- and salt-challenged stems, while exhibited superior stability in drought-affected roots/leaves, heavy-metal-stressed tissues, and salt-treated leaves. Validation via the drought-inducible MYB transcription factor confirmed reference gene reliability. : This work pioneers a standardized reference gene framework for under multi-stress conditions, offering essential methodological foundations for subsequent molecular research in this medicinal plant.