title: Plant fluid proteomics: Delving into the xylem sap, phloem sap and apoplastic fluid proteomes.
abstract: The phloem sap, xylem sap and apoplastic fluid play key roles in long and short distance transport of signals and nutrients, and act as a barrier against local and systemic pathogen infection. Among other components, these plant fluids contain proteins which are likely to be important players in their functionalities. However, detailed information about their proteomes is only starting to arise due to the difficulties inherent to the collection methods. This review compiles the proteomic information available to date in these three plant fluids, and compares the proteomes obtained in different plant species in order to shed light into conserved functions in each plant fluid. Inter-species comparisons indicate that all these fluids contain the protein machinery for self-maintenance and defense, including proteins related to cell wall metabolism, pathogen defense, proteolysis, and redox response. These analyses also revealed that proteins may play more relevant roles in signaling in the phloem sap and apoplastic fluid than in the xylem sap. A comparison of the proteomes of the three fluids indicates that although functional categories are somewhat similar, proteins involved are likely to be fluid-specific, except for a small group of proteins present in the three fluids, which may have a universal role, especially in cell wall maintenance and defense. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock.
authors.affiliation: University of East Anglia/John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
authors.forename: Jorge
authors.initials: J
authors.lastname: Rodríguez-Celma
authors.affiliation: Department of Plant Nutrition, Aula Dei Experimental Station, Consejo Superior de Investigaciones Científicas (CSIC), P.O. Box 13034, E-50080 Zaragoza, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Ceballos-Laita
authors.affiliation: USDA-ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Grusak
authors.affiliation: Department of Plant Nutrition, Aula Dei Experimental Station, Consejo Superior de Investigaciones Científicas (CSIC), P.O. Box 13034, E-50080 Zaragoza, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Abadía
authors.affiliation: Department of Plant Nutrition, Aula Dei Experimental Station, Consejo Superior de Investigaciones Científicas (CSIC), P.O. Box 13034, E-50080 Zaragoza, Spain; USDA-ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030, USA. Electronic address: lopezmil@bcm.edu.
authors.forename: Ana-Flor
authors.initials: AF
authors.lastname: López-Millán
mesh_terms: D052585:Phloem / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D052584:Xylem / Q000378:metabolism*
chemical_list: D010940:Plant Proteins
keywords: Apoplastic fluid; Phloem sap; Proteome; Xylem sap