Comparative Proteomic and Physiological Analyses Reveal the Protective Effect of Exogenous Polyamines in the Bermudagrass (<i>Cynodon dactylon</i>) 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.多胺（Polyamines）可增强多种植物的非生物胁迫耐受性。然而，多胺对目前应用最为广泛的暖季型草坪草——狗牙根（bermudagrass）的非生物胁迫效应及生理变化的调控作用仍不明晰。本研究中，外源多胺预处理可提升狗牙根的盐胁迫与干旱胁迫耐受性。为进一步探究多胺介导的胁迫应答机制，本研究开展了比较蛋白质组学分析，成功鉴定出36种至少受两类多胺共同调控的狗牙根蛋白，其中12种蛋白表达量上调、20种蛋白表达量下调，另有4种为特异性表达蛋白。其中，参与电子传递与能量通路的蛋白显著富集，核苷二磷酸激酶（NDPK）及三种抗氧化酶均受到多胺的广泛调控。对活性氧（reactive oxygen species, ROS）水平的分析表明，多胺诱导产生的过氧化氢（H₂O₂）在非生物胁迫条件下可能发挥双重作用。此外，外源多胺处理后还可观察到渗透调节物质的积累，这与蛋白质组学结果相符——多个参与碳固定通路的蛋白均受多胺预处理的共同调控。综上，本研究提出多胺可通过激活多条通路提升狗牙根对盐胁迫与干旱胁迫的适应性。该研究结果可应用于草坪草与作物的基因工程改造，以提升其胁迫耐受性。