Project description:Alkali-salinity is a major abiotic stress that limits plant growth and productivity. Studying mechanisms of alkali-salinity tolerance in halophytic plants will provide valuable information for underlying plant alkali-salinity tolerance. Puccinellia tenuiflora is considered as an ideal model plant for studying the alkali-salinity tolerant mechanisms in plants. In this study, the NaHCO3-responsive molecular mechanisms in P. tenuiflora leaves were investigated using a combined physiological and proteomic approaches. Our results implied some specific NaHCO3-responsive mechanisms in leaves from P. tenuiflora. They are (1) reduction of photosynthesis attributed to the decrease of the abundance of Calvin cycle enzymes, (2) accumulation of Na+ and K+ caused ion-specific stress, (3) accumulation of proline, soluble sugar and betaine enhanced the ability of osmotic regulation, (4) diverse reactive oxygen species (ROS) scavenging mechanisms under different NaHCO3 concentrations, and (5) alternative protein synthesis and processing strategies in chloroplast and cytoplasm. All these provide important evidence for understanding NaHCO3-responsive mechanisms in P. tenuiflora.
Project description:Puccinellia tenuiflora is a monocotyledonous halophyte species belonging to the Gramineae. It has strong ability for surviving in the extreme saline-alkali soil (pH range of 9-10). In the present study, proteins from leaves under various Na2CO3 treatments were separated and visualized on Coomassie Brilliant Blue-stained two-dimensional gel electrophoresis (2-DE) gels. After gel image analysis on the base of the calculated average vol% values of each protein spot, 174 protein spots were detected as abundance changed protein spots (1.5-fold changes, p < 0.05). Among them, 104 protein spots were identified using MALDI-TOF MS/MS and Mascot database searching. Thus the 104 protein identities represented 80 unique proteins were taken as Na2CO3-responsive proteins in leaves. After integrative analysis by BLAST alignment, Kyoto Encyclopedia of Genes and Genomes, and referring information from related literature, they were classified into 10 functional categories, including photosynthesis, carbohydrate and energy metabolism, other metabolisms, stress and defense, membrane and transport, signaling, protein synthesis, folding, and turnover, cell wall mechanism, cell cycle, and miscellaneous or unknown.
Project description:Alkali-salinity exerts severe osmotic, ionic, and high-pH stresses to plants. Photosynthetic machinery is especially sensitive to saline-alkali stress. In addition, reversible protein phosphorylation also play crucial roles in plant salt resistance. While our knowledge on protein phosphorylation events in salt stress response is very limited. Few studies have been published involving photosynthetic protein phosphorylation modulation to improve salt resistance. In the present study, we investigated the Na2CO3-responsive characteristics in Puccinellia tenuiflora chloroplasts using stable isotope dimethyl labeled phosphoproteomic approach. A total of 161 unique phosphopeptides were identified, and 137 phosphopeptides were quantified by dimethyl labeling. Among them, 50 proteins were quantified as Na2CO3-responsive proteins with 57 phosphosites, including 33 increased and 14 decreased. Importantly, 26 phosphosites were newly identified as Na2CO3-responsive phosphoproteins in plants, which were supposed to be crucial for regulating photosynthesis, membrane and transporting, signaling, stress response, and protein synthesis and turnover. Among them, seven light harvesting proteins, six PSII proteins, five PSI proteins, three electron transfer chain proteins, and two Calvin cycle-related proteins were increased, but five ATP synthase subunits and sucrose-phosphate synthase were decreased at phosphorylation level. Besides, Na+/H+ antiporter, villin-2, and two thylakoid organization related proteins were increased at phosphorylation level. Two signaling related proteins and most protein species in charge of gene expression and protein turnover were enhanced at phosphorylation level at 24h after Na2CO3 treatment.