Biology Reference
In-Depth Information
Chapter 28
Xylem Sap Proteomics
Thomas Dugé de Bernonville , Cécile Albenne , Matthieu Arlat ,
Laurent Hoffmann , Emmanuelle Lauber , and Elisabeth Jamet
Abstract
Proteomic analysis of xylem sap has recently become a major fi eld of interest to understand several biological
questions related to plant development and responses to environmental clues. The xylem sap appears as a
dynamic fl uid undergoing changes in its proteome upon abiotic and biotic stresses. Unlike cell compart-
ments which are amenable to purifi cation in suffi cient amount prior to proteomic analysis, the xylem sap
has to be collected in particular conditions to avoid contamination by intracellular proteins and to obtain
enough material. A model plant like
Arabidopsis thaliana
is not suitable for such an analysis because effi cient
harvesting of xylem sap is diffi cult. The analysis of the xylem sap proteome also requires specifi c procedures
to concentrate proteins and to focus on proteins predicted to be secreted. Indeed, xylem sap proteins
appear to be synthesized and secreted in the root stele or to originate from dying differentiated xylem cells.
This chapter describes protocols to collect xylem sap from
Brassica
species and to prepare total and
N
-glycoprotein extracts for identifi cation of proteins by mass spectrometry analyses and bioinformatics.
Key words
Cell wall, Glycoproteomics, Xylem sap
1
Introduction
During land colonization by plants, about 430 million years ago,
the multicellular photosynthetic organisms had to undergo a series
of evolutionary events to establish the conditions for successful
colonization of new environments like improvement of photosyn-
thetic activity and absorption of water and nutriments from the
soil. As a consequence, to interconnect all organs and to remain
hydrated, terrestrial plants acquired conducting specialized tissues
[
1
]. The vascular network of seed plants is organized in bundles
and is composed of two major tissue types, xylem and phloem,
originating from the procambium, the vascular meristem. Both
tissues typically comprise specialized cell types, including conduct-
ing elements, and cells that fulfi ll nourishing (parenchyma) and
mechanical strengthening (fi bers) functions. The conducting
tracheary elements of xylem allow the hydration of the plant body
