Responses of Sour Jujube Seedlings from Different Germplasm Sources to Drought Stress During the Seedling Stage and Transcriptome Analysis

Background: Global climate change has intensified the frequency and severity of drought events, posing a serious threat to agricultural and ecosystem stability. sour jujube is an important ecological and economic tree species in China's northwest region, exhibits strong drought resistance potential, yet its systemic drought tolerance mechanisms remain unclear. Results:This study utilized sour jujube seedlings from six provenances—Jiaxian, Shenmu, Ganquan, and Yancuan in Shaanxi; Zaozhuang in Shandong; and Tangshan in Hebei—to comprehensively evaluate their growth, physiological, photosynthetic, and molecular responses under continuous drought stress. Results indicate that drought stress significantly suppressed seedling growth, induced enhanced antioxidant enzyme activity and accumulation of osmotic regulatory substances, while decreasing photosynthetic efficiency. Among the sources, Shenmu exhibited optimal performance across most indicators and demonstrated the strongest drought resistance. Transcriptome analysis revealed 128,456 unigenes, from which 3,629 differentially expressed genes (DEGs) were identified—2,015 up-regulated and 1,614 down-regulated. These DEGs were primarily enriched in pathways including secondary metabolite synthesis, phenylpropanoid biosynthesis, and starch and sucrose metabolism. A total of 57 transcription factor families were identified, including key regulators such as bHLH, NAC, and WRKY. Conclusions: This study reveals the multi-level regulatory network of sour jujube in response to drought, providing theoretical basis and candidate gene resources for drought-resistant germplasm breeding and gene function analysis.