Integration of physiological and transcriptomic analyses unveils the drought resistance mechanism in Solanum tuberosum L.

Drought constitutes a significant limiting factor globally, impacting plant growth and development while constraining productivity, with its influence intensifying under global climate change. China’s primary potato-producing regions predominantly lie within arid and semi-arid zones, where frequent drought presents a core constraint on the potato industry. To clarify the differential mechanisms underlying drought responses, this study compared the physiological traits and transcriptomic profiles of drought-tolerant (‘LS10’) and a water-sensitive (‘Atlantic’) potato cultivars under drought stress. Physiological analysis identified marked cultivar-specific differences in malondialdehyde (MDA) and proline (Pro) contents, superoxide dismutase (SOD) and peroxidase (POD) activities, and relative leaf chlorophyll content (RLCC) under water deficit. Under drought, ‘LS10’ exhibited compensatory SOD and POD activation at 30 days, delayed membrane damage progression, sustained Pro accumulation, and maintained stable RLCC, whereas ‘Atlantic’ showed earlier MDA elevation, persistently weak antioxidant responses, and continuously declining RLCC. Transcriptome sequencing of ‘LS10’ leaves identified 3,077, 781, and 1158 differentially expressed genes (DEGs) at 15, 30, and 45 days of drought stress, respectively, which were primarily enriched in photosynthesis-related and metabolic pathways. RT-qPCR of DEGs in both cultivars further showed that six light-harvesting chlorophyll a/b -binding proteins (LHCP) genes were strongly induced in ‘LS10’ but remained near baseline in ‘Atlantic’, revealing their potential as key candidate genes for drought tolerance. The two cultivars displayed essential differences in drought protection efficiency. ‘LS10’ mitigated oxidative damage via enhanced antioxidant enzyme activity and osmoprotectant accumulation while preserving photosynthetic stability, whereas ‘Atlantic’ failed to mount effective antioxidant defenses and suffered progressive photosynthetic decline. These findings provide a theoretical basis for understanding cultivar-specific drought tolerance mechanisms and offer candidate genetic targets for improving potato drought resistance.