Omics-Based Study of Salt-Alkali Stress Mechanisms in Mountain Peach (Prunus davidiana Carr.) in Northwest China

Long-term field evidence shows that peach trees grafted onto mountain peach ( Prunus davidiana Carr.) rootstocks exhibit superior salt tolerance in Northwest China’s saline-alkali soils compared to those on hairy peach ( Prunus persica L.) rootstocks, yet the mechanism is unclear. This study compared physiological and transcriptomic providing a theoretical basis for breeding.responses of ‘Longmi 9’ peach grafted onto both rootstocks under gradient salt stress. Mountain peach effectively restricted leaf Na⁺ accumulation (up to 36.36% reduction) and Cl⁻ influx, maintained a higher K⁺/Na⁺ ratio, and showed only half the reduction in stomatal aperture under high stress, thereby preserving photosynthesis. In contrast, hairy peach exhibited sensitive ion accumulation. Transcriptomics revealed a more targeted response in mountain peach, with 256 differentially expressed genes (DEGs) across three stress levels versus 1,196 in hairy peach. Both varieties activated phenylpropanoid and α-linolenic acid metabolism pathways. Notably, mountain peach uniquely coordinated glutathione, nitrogen, and pyruvate metabolism into a synergistic network, whereas hairy peach relied more on flavonoid biosynthesis. Quantitative real-time PCR (qRT-PCR) validation of six co-enriched DEGs, such as PRX44 , OPR2 and CCR2 , confirmed expression trends consistent with the transcriptome data, thereby verifying its reliability. This work elucidates the multilevel, coordinated regulatory mechanism conferring salt tolerance in mountain peach, providing robust theoretical foundations for the development of salt-tolerant peach cultivars.