Abstracts now available online - Euro Fed Lipid

Extracellular BODYGUARD involved in the formation of cuticle
Alexander Yephremov 1 , Andrea Faust 1 , Derry Voisin 1 , Sergey Kurdyukov 1 , Christiane
Nawrath 2 , Nadia Efremova 1 , Rochus Franke 3 , Lukas Schreiber 3 , Heinz Saedler 1
1
Max-Planck-Institut für Züchtungsforschung, Carl von Linné Weg 10, 50829 Köln,
Germany; 2 Département de Biologie Moléculaire Végétale, Université de Lausanne,
CH-1015 Lausanne, Switzerland; 3 Institut für Zelluläre and Molekulare Botanik,
Universität Bonn, Kirschallee 1, D-53115 Bonn, Germany.
The extracellular matrix produced by epidermal cells is specialized to protect plants
against adverse environmental conditions and pathogens and includes the cuticle
barrier the outermost cell wall of the epidermis made up of lipid molecules. Some
extracellular lipids are soluble and can be extracted with organic solvents into the wax
fraction, while others are connected to cell wall carbohydrates and interconnected by
ester bonds. A number of Arabidopsis mutants, which show apparent defects in the
cuticular barrier, represent a valuable genomic tool not only to identify genes involved in
the formation of the cuticle but also to elucidate how cuticular lipids modulate
development of plants. Here we report characterization of an Arabidopsis cuticular
mutant, called bodyguard (bdg), which displays pleiotropical effects of the mutation on
growth, morphology, cell viability and differentiation. The bdg mutant accumulates
significantly more cell wall-bound lipids and epicuticular waxes than wild-type plants.
The RT-PCR analysis shows in bdg transcriptional activation of genes involved in the
decarbonylation pathway, which catalyzes the formation of alkanes with odd-numbered
chain lengths in epicuticular wax. However, with regard to cuticular appearance and
structure, bdg is reminiscent to transgenic Arabidopsis plants expressing extracellular
fungal cutinase, which exhibit defects characteristic of loss of cuticle structure.
Strikingly, molecular cloning of BDG shows that it encodes a member of the α/βhydrolase
fold superfamily of proteins, to which extracellular fungal cutinases belong.
Expression of BDG is restricted to epidermal cells. Furthermore, subcellular
immunolocalization shows that BDG is a polarly localized protein that accumulates in
the outermost cell wall in the epidermis. Thus, BDG defines a new family of plantspecific
α/β hydrolases. We propose that BDG is required for polymerization processes
in the cuticular layer of the cell wall or the cuticle proper.