ALBERT

Beschreibung: 〈h3〉Abstract〈/h3〉 〈span〉 〈h3〉Aims〈/h3〉 〈p〉Soil alkalization imposes severe ion toxicity, osmotic stress, and high pH stress to plants, inhibiting their growth and productivity. NaHCO〈sub〉3〈/sub〉 is a main component of alkaline soil. However, knowledge of the NaHCO〈sub〉3〈/sub〉-responsive proteomic pattern of alkaligrass is still lacking. Alkaligrass (〈em〉Puccinellia tenuiflora〈/em〉) is a monocotyledonous halophyte pasture widely distributed in the Songnen Plain in Northeastern China. This study aims to investigate the NaHCO〈sub〉3〈/sub〉-responsive molecular mechanisms in the alkaligrass plants.〈/p〉 〈/span〉 〈span〉 〈h3〉Methods〈/h3〉 〈p〉An integrative approach including photosynthetic and redox physiology, and comparative proteomics was used.〈/p〉 〈/span〉 〈span〉 〈h3〉Results〈/h3〉 〈p〉NaHCO〈sub〉3〈/sub〉 decreased photosynthesis, but increased nonphotochemical quenching, increased membrane electrolyte leakage of alkaligrass, and increased proline and glycine betaine concentrations in leaves. In addition, the NaHCO〈sub〉3〈/sub〉 stress increased Na〈sup〉+〈/sup〉 concentration and decreased K〈sup〉+〈/sup〉/Na〈sup〉+〈/sup〉 ratio in leaves, while Ca〈sup〉2+〈/sup〉 and Mg〈sup〉2+〈/sup〉 concentrations were maintained, contributing to signaling and homeostasis of ion and enzyme activity. Furthermore, O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 generation rate and H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 concentration were increased, and the activities of ten antioxidant enzymes and antioxidant concentrations were changed in response to the NaHCO〈sub〉3〈/sub〉 stress. Proteomics revealed 90 NaHCO〈sub〉3〈/sub〉-responsive proteins, 54% of which were localized in chloroplasts. They were mainly involved in signaling, photosynthesis, stress and defense, carbohydrate and energy metabolism, as well as protein synthesis, processing and turnover. Some protein abundances did not correlate well with their activities, implying that the enzyme activities were affected by NaHCO〈sub〉3〈/sub〉-induced post-translational modifications.〈/p〉 〈/span〉 〈span〉 〈h3〉Conclusions〈/h3〉 〈p〉To cope with the NaHCO〈sub〉3〈/sub〉 stress, alkaligrass deployed multiple strategies, including triggering phospholipase D (PLD)-mediated Ca〈sup〉2+〈/sup〉 signaling pathways, enhancing diverse reactive oxygen species (ROS) scavenging pathways, and regulating chloroplast protein synthesis and processing.〈/p〉 〈/span〉