title: Protein Dynamics in the Plant Extracellular Space.
abstract: The extracellular space (ECS or apoplast) is the plant cell compartment external to the plasma membrane, which includes the cell walls, the intercellular space and the apoplastic fluid (APF). The present review is focused on APF proteomics papers and intends to draw information on the metabolic processes occurring in the ECS under abiotic and biotic stresses, as well as under non-challenged conditions. The large majority of the proteins detected are involved in "cell wall organization and biogenesis", "response to stimulus" and "protein metabolism". It becomes apparent that some proteins are always detected, irrespective of the experimental conditions, although with different relative contribution. This fact suggests that non-challenged plants have intrinsic constitutive metabolic processes of stress/defense in the ECS. In addition to the multiple functions ascribed to the ECS proteins, should be considered the interactions established between themselves and with the plasma membrane and its components. These interactions are crucial in connecting exterior and interior of the cell, and even simple protein actions in the ECS can have profound effects on plant performance. The proteins of the ECS are permanently contributing to the high dynamic nature of this plant compartment, which seems fundamental to plant development and adaptation to the environmental conditions.
authors.affiliation: Centro de Investigação das Ferrugens do Cafeeiro (CIFC), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (UL), Quinta do Marquês, 2784-505 Oeiras, Portugal. leonorguimaraes@isa.ulisboa.pt.|Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa (UL), 1349-017 Lisboa, Portugal. leonorguimaraes@isa.ulisboa.pt.
authors.forename: Leonor
authors.initials: L
authors.lastname: Guerra-Guimarães
authors.affiliation: Instituto de Tecnologia Química e Biológica (ITQB), Universidade NOVA de Lisboa (UNL), 2780-157 Oeiras, Portugal. cm.pinheiro@fct.unl.pt.|Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa (UNL), 2829-516 Caparica, Portugal. cm.pinheiro@fct.unl.pt.
authors.forename: Carla
authors.initials: C
authors.lastname: Pinheiro
authors.affiliation: Instituto de Tecnologia Química e Biológica (ITQB), Universidade NOVA de Lisboa (UNL), 2780-157 Oeiras, Portugal. ichaves@itqb.unl.pt.|Instituto de Biologia Experimental e Tecnológica (IBET), 2780-157 Oeiras, Portugal. ichaves@itqb.unl.pt.
authors.forename: Inês
authors.initials: I
authors.lastname: Chaves
authors.affiliation: Departamento de Fitossanidade, Faculdade de Agronomia Eliseu Maciel (FAEM), Universidade Federal de Pelotas (UFPEL), 96010-610 Pelotas-RS, Brazil. danrbarros@hotmail.com.
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Barros
authors.affiliation: Instituto de Tecnologia Química e Biológica (ITQB), Universidade NOVA de Lisboa (UNL), 2780-157 Oeiras, Portugal. ricardo@itqb.unl.pt.
authors.forename: Cândido P
authors.initials: CP
authors.lastname: Ricardo
keywords: apoplastic fluid; biological processes; cell wall; dicot plants; intercellular space; proteomic analysis