title: A comparative proteomic analysis of tomato leaves in response to waterlogging stress.
abstract: A comparative proteomic approach has been adopted in combination with physiological and biochemical analysis of tomato leaves responding to waterlogging stress. Waterlogging resulted in increases of relative ion leakage, lipid peroxidation and in vivo H2O2 content, whereas the chlorophyll content was decreased. Histocytochemical investigations with 3,3'-diaminobenzidine to localize H2O2 and Evans blue to detect dead cells suggested that oxidative stress has a significant role to leaf senescence. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), the most abundant leaf protein, was successfully reduced from the samples by a fractionation method based on 15% polyethylene glycol (PEG). Elimination of Rubisco was further confirmed by Western blot analysis. To elucidate the temporal changes of the protein patterns in tomato leaves, the total soluble and the PEG-fractionated proteins were separated by two-dimensional electrophoresis (2-DE) and visualized by Coomassie Brilliant Blue staining. A total of 52 protein spots were differentially expressed, wherein 33 spots were identified by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry or electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis. The identified proteins are involved in several processes, i.e. photosynthesis, disease resistance, stress and defense mechanisms, energy and metabolism and protein biosynthesis. Results from 2-DE analysis, combined with immunoblotting clearly showed that the fragments of Rubisco large subunit were significantly degraded. This could result from a higher production of reactive oxygen species in leaves under waterlogging stress. Furthermore, four differentially accumulated proteins were analyzed at the mRNA level, confirming the differential gene expression levels and revealing that transcription levels are not always concomitant to the translation level. A number of novel proteins were differentially expressed or appeared only in the PEG-fractionated protein samples, indicating that PEG fractionation system can be used as a versatile protein fractionation technique in proteomic analysis to identify novel or low-abundant proteins from all kinds of plant species.
authors.affiliation: Division of Applied Life Sciences (BK21 and EB-NCRC), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea.
authors.forename: Nagib
authors.initials: N
authors.lastname: Ahsan
authors.forename: Dong-Gi
authors.initials: DG
authors.lastname: Lee
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Kyu Young
authors.initials: KY
authors.lastname: Kang
authors.forename: Jeong Dong
authors.initials: JD
authors.lastname: Bahk
authors.forename: Myung Suk
authors.initials: MS
authors.lastname: Choi
authors.forename: In-Jung
authors.initials: IJ
authors.lastname: Lee
authors.forename: Jenny
authors.initials: J
authors.lastname: Renaut
authors.forename: Byung-Hyun
authors.initials: BH
authors.lastname: Lee
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D004573:Electrolytes / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics*; D020543:Proteome; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D014867:Water / Q000502:physiology*
chemical_list: D004573:Electrolytes; D010940:Plant Proteins; D020543:Proteome; D014867:Water; D002734:Chlorophyll; D006861:Hydrogen Peroxide; D012273:Ribulose-Bisphosphate Carboxylase