Comparative Proteomic and Physiological Analyses Reveal the Protective Effect of Exogenous Polyamines in the Bermudagrass (Cynodon dactylon) Response to Salt and Drought Stresses

Polyamines conferred enhanced abiotic stress tolerance in multiple plant species. However, the effect of polyamines on abiotic stress and physiological change in bermudagrass, the most widely used warm-season turfgrasses, are unknown. In this study, pretreatment of exogenous polyamine conferred increased salt and drought tolerances in bermudagrass. Comparative proteomic analysis was performed to further investigate polyamines mediated responses, and 36 commonly regulated proteins by at least two types of polyamines in bermudagrass were successfully identified, including 12 proteins with increased level, 20 proteins with decreased level and other 4 specifically expressed proteins. Among them, proteins involved in electron transport and energy pathways were largely enriched, and nucleoside diphosphate kinase (NDPK) and three antioxidant enzymes were extensively regulated by polyamines. Dissection of reactive oxygen species (ROS) levels indicated that polyamine-derived H2O2 production might play dual roles under abiotic stress conditions. Moreover, accumulation of osmolytes was also observed after application of exogenous polyamines, which is consistent with proteomics results that several proteins involved in carbon fixation pathway were mediated commonly by polyamines pretreatment. Taken together, we proposed that polyamines could activate multiple pathways that enhance bermudagrass adaption to salt and drought stresses. These findings might be applicable for genetically engineering of grasses and crops to improve stress tolerance.