StNCED2 confers drought tolerance via enhanced ABA synthesis

• Twelve CCD family members identified in potato. • StNCED2 transgenic plants have higher survival rates under drought stress. • Overexpression of StNCED2 significantly enhances ABA biosynthesis in transgenic plants. • Overexpression of StNCED2 increases the sensitivity of transgenic plants to ABA. Carotenoid cleavage dioxygenases (CCDs), crucial non-heme pigment oxygenases regulating plant stress responses, remain poorly characterized functionally in potato despite extensive research on this gene family. In this study, genome-wide analysis identified 12 StCCD family genes in potato, which were classified into five subfamilies. Gene structure and conserved motif analyses revealed significant intra-subfamily conservation, the gene promoter region is rich in abiotic stress and hormone response elements. Transcriptome analysis demonstrated that StNCED2 expression level was dramatically up-regulated under drought stress. Further functional characterization revealed that StNCED2 overexpression in Arabidopsis significantly enhanced drought tolerance. Transgenic lines exhibited reduced malondialdehyde (MDA) accumulation and reactive oxygen species (ROS) levels, along with elevated proline (Pro) content and enhanced antioxidant enzyme activities compared to wild-type (WT) plants. Furthermore, qRT-PCR analysis demonstrated that multiple stress response and ABA synthesis related genes were markedly up-regulated in transgenic plants under drought conditions. Additionally, StNCED2 overexpression increased ABA sensitivity, as evidenced by shorter root lengths and delayed germination in the presence of exogenous ABA. High performance liquid chromatography (HPLC) analysis revealed that under drought stress, ABA levels in transgenic lines increased significantly by 26.5% (OE9), 20.7% (OE11), and 69.2% (OE14) compared to WT plants ( p < 0.01). Collectively, these findings demonstrate that StNCED2 positively regulates drought tolerance in Arabidopsis through enhanced ABA biosynthesis.