title: Proteomic response of rice seedling leaves to elevated CO2 levels.
abstract: Previous investigations of plant responses to higher CO 2 levels were mostly based on physiological measurements and biochemical assays. In this study, a proteomic approach was employed to investigate plant response to higher CO 2 levels using rice as a model. Ten-day-old seedlings were progressively exposed to 760 ppm, 1140 ppm, and 1520 ppm CO 2 concentrations for 24 h each. The net photosynthesis rate ( P n), stomatal conductance ( G s), transpiration rate ( E), and intercellular to ambient CO 2 concentration ratio ( C i/ C a) were measured. P n, G s, and E showed a maximum increase at 1140 ppm CO 2, but further exposure to 1520 ppm for 24 h resulted in down regulation of these. Proteins extracted from leaves were subjected to 2-DE analysis, and 57 spots showing differential expression patterns, as detected by profile analysis, were identified by MALDI-TOF/TOF-MS. Most of the proteins belonged to photosynthesis, carbon metabolism, and energy pathways. Several molecular chaperones and ascorbate peroxidase were also found to respond to higher CO 2 levels. Concomitant with the down regulation of P n and G s, the levels of enzymes of the regeneration phase of the Calvin cycle were decreased. Correlations between the protein profiles and the photosynthetic measurements at the three CO 2 levels were explored.
authors.affiliation: Laboratory of Molecular Biology and Protein Science Laboratory of the Ministry of Education, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China.
authors.forename: Saleem A
authors.initials: SA
authors.lastname: Bokhari
authors.forename: Xiang-Yuan
authors.initials: XY
authors.lastname: Wan
authors.forename: Yi-Wei
authors.initials: YW
authors.lastname: Yang
authors.forename: Lu
authors.initials: L
authors.lastname: Zhou
authors.forename: Wan-Li
authors.initials: WL
authors.lastname: Tang
authors.forename: Jin-Yuan
authors.initials: JY
authors.lastname: Liu
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism / Q000502:physiology*; D015180:Electrophoresis, Gel, Two-Dimensional; D012275:Oryza / Q000254:growth & development / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism*; D010940:Plant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000502:physiology; D020543:Proteome / Q000502:physiology*; D036226:Seedlings / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D020543:Proteome; D002245:Carbon Dioxide