title: Comparative proteomic analysis of labellum and inner lateral petals in Cymbidium ensifolium flowers.
abstract: The labellum in orchids shares homology with the inner lateral petals of the flower. The labellum is a modified petal and often distinguished from other petals and sepals due to its large size and irregular shape. Herein, we combined two-dimensional gel electrophoresis (2-DE) and matrix assisted laser desorption/ionization time of flight/time of flight (MALDI-TOF/TOF) approaches to identify the differentially expressed proteome between labellum and inner lateral petal in one of Orchid species (C. ensifolium). A total of 30 protein spots were identified, which showed more than a two-fold significant difference (p<0.05) in their expression. Compared with C. ensifolium transcriptome (sequenced in house), 21 proteins matched the translated nucleotide. The proteins identified were classified into 48 categories according to gene ontology (GO). Additionally, these proteins were involved in 18 pathways and 9 possible protein-protein interactions. Serine carboxypeptidase and beta-glucosidase were involved in the phenylpropanoid pathway, which could regulate biosynthesis of floral scent components. Malate dehydrogenase (maeB) and triosephosphate isomerase (TPI) in carbon fixation pathway could regulate the energy metabolism. Xyloglucan endotransglucosylase/hydrolase (XET/XTH) could promote cell wall formation and aid the petal's morphogenesis. The identification of such differentially expressed proteins provides new targets for future studies; these will assess the proteins' physiological roles and significance in labellum and inner lateral petals.
authors.affiliation: Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China. lixiaobai@mail.zaas.ac.cn.
authors.forename: Xiaobai
authors.initials: X
authors.lastname: Li
authors.affiliation: Cixi Agricultural Technology Extension Center, Cixi, Ningbo 315300, China. xuwei1364@sohu.com.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Xu
authors.affiliation: Department of Horticulture, Washington State University, Pullman, WA 99164, USA. Moytri.roychowdhury@wsu.edu.
authors.forename: Moytri Roy
authors.initials: MR
authors.lastname: Chowdhury
authors.affiliation: College of Life Sciences, Hubei University, Wuhan 430062, China. fengjin1989@yeah.net.
authors.forename: Feng
authors.initials: F
authors.lastname: Jin
mesh_terms: D030562:Databases, Protein; D015180:Electrophoresis, Gel, Two-Dimensional; D035264:Flowers / Q000378:metabolism; D058977:Molecular Sequence Annotation; D029595:Orchidaceae / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D025941:Protein Interaction Mapping; D020543:Proteome / Q000032:analysis*; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D059467:Transcriptome
chemical_list: D010940:Plant Proteins; D020543:Proteome