Morpho-physiological and proteomic responses to water stress in two contrasting tobacco varieties.

To gain insight into the molecular mechanisms underpinning tobacco (Nicotiana tabacum) tolerance to drought stress, we integrated anatomical, physiological, and proteomic analyses of drought-tolerant (Yuyan6, [Y6]) and -sensitive (Yunyan87 [Y87]) varieties. In comparison to Y87, Y6 exhibited higher water retention capability, improved photosynthetic performance, delayed leaf-senescence, stable leaf ultrastructure, a stronger antioxidant defense, and lesser ROS accumulation when subjected to water stress. Using an iTRAQ-based proteomics approach, 405 and 1,560 differentially accumulated proteins (DAPs) were identified from Y6 and Y87 plants, respectively, of which 114 were found to be present in both cultivars. A subsequent functional characterization analysis revealed that these DAPs were significantly enriched in eight biological processes, six molecular functions, and six cellular components and displayed differential expression patterns in Y6 and Y87 plants, suggesting that the response to water stress between both varieties differed at the proteomic level. Furthermore, we constructed protein coexpression networks and identified hub proteins regulating tobacco defenses to water stress. Additionally, qPCR analysis indicated that the majority of genes encoding selected proteins showed consistency between mRNA levels and their corresponding protein expression levels. Our results provide new insights into the genetic regulatory mechanisms associated with drought response in tobacco plants.