Pseudomonas sp. UW4 enhances drought tolerance in garlic via lipid-protein association network and repairing tissue structure

Background Plant growth-promoting bacteria effectively alleviate crop drought stress, yet the underlying lipid and protein regulatory associations remain poorly understood. ‘Ledu Purple Garlic’ was used as experimental material to elucidate the regulatory mechanism of Pseudomonas sp. UW4 in improving garlic drought tolerance. Methods Integrative analyses of root and leaf microstructural and ultrastructural observations, lipidomics, and proteomics were performed in this study. Results Microscopic results demonstrated that drought stress caused severe morphological and structural damage to tissues and organelles in garlic roots and leaves, whereas inoculation with strain UW4 substantially repaired injured cells and preserved the structural integrity of stomata, vascular bundles, and intracellular organelles. Lipidomic profiling revealed that drought stress drastically repressed triacylglycerol (TAG) accumulation and reshaped global lipid metabolic profiles, while inoculation with strain UW4 reversed the stress-induced metabolic disorder of TAGs, membrane lipids, and signaling lipids, thereby restoring lipid metabolic homeostasis. Proteomic analysis identified a large set of drought-responsive differentially expressed proteins, among which key proteins including CESA5, CALS9, WRKY14, and HSP70-14 were all significantly upregulated by strain UW4. These functional proteins modulate cell wall biosynthesis, stress signal transduction, and protein stability, sustaining basal cellular metabolism and redox balance and ultimately mitigating drought-triggered oxidative damage. Multi-omics integration further validated that strain UW4 is associated with remodeling of a lipid-protein association network with TAGs and HSP70-14 as highly connected nodes, and that WRKY14 may be involved in lipid metabolic signaling. Conclusion Collectively, strain UW4 confers enhanced drought tolerance in garlic through structural damage repair, lipid metabolic homeostasis reconstruction, and lipid-protein synergistic modulation. This work elucidates the molecular mechanism underlying plant growth-promoting bacteria-mediated stress tolerance in Allium crops and provides solid theoretical support for the application of microbial inoculants in arid agricultural ecosystems.