ArabidopsisDeficient in Cutin FerulateEncodes a Transferase Required for Feruloylation of ω-Hydroxy Fatty Acids in Cutin Polyester    

Abstract

The cuticle is a complex aliphatic polymeric layer connected to the cell wall and covers surfaces of all aerial plant organs. The cuticle prevents nonstomatal water loss, regulates gas exchange, and acts as a barrier against pathogen infection. The cuticle is synthesized by epidermal cells and predominantly consists of an aliphatic polymer matrix (cutin) and intracuticular and epicuticular waxes. Cutin monomers are primarily C 16 and C 18 unsubstituted, v-hydroxy, and a,v-dicarboxylic fatty acids. Phenolics such as ferulate and p-coumarate esters also contribute to a minor extent to the cutin polymer. Here, we present the characterization of a novel acyl-coenzyme A (CoA)-dependent acyl-transferase that is encoded by a gene designated Deficient in Cutin Ferulate (DCF). The DCF protein is responsible for the feruloylation of v-hydroxy fatty acids incorporated into the cutin polymer of aerial Arabidopsis (Arabidopsis thaliana) organs. The enzyme specifically transfers hydroxycinnamic acids using v-hydroxy fatty acids as acyl acceptors and hydroxycinnamoyl-CoAs, preferentially feruloyl-CoA and sinapoyl-CoA, as acyl donors in vitro. Arabidopsis mutant lines carrying DCF loss-of-function alleles are devoid of rosette leaf cutin ferulate and exhibit a 50% reduction in ferulic acid content in stem insoluble residues. DCF is specifically expressed in the epidermis throughout all green Arabidopsis organs. The DCF protein localizes to the cytosol, suggesting that the feruloylation of cutin monomers takes place in the cytoplasm.The cuticle, a complex polymeric layer connected to the cell wall of epidermal cells, covers the surfaces of all aerial plant organs. The cuticle prevents nonstomatal water loss, regulates gas exchange, acts as a barrier against pathogen infection, and prevents organ fusions (Lolle et al., 1998;Sieber et al., 2000). The plant cuticle is synthesized by epidermal cells and predominantly consists of a lipophilic polymer matrix (cutin) and intracuticular and epicuticular waxes. Cutin monomers are primarily aliphatic C 16 and C 18 unsubstituted, v-hydroxy, and a,v-dicarboxylic fatty acids. Polyhydroxy fatty acids, fatty alcohols, phenolic acids such as ferulic and p-coumaric acid, and glycerol may also contribute to cutin composition in different plant species (Baker and Martin, 1963;Kolattukudy, 1980;Pollard et al., 2008;Samuels et al., 2008;Schreiber, 2010).In Arabidopsis (Arabidopsis thaliana), several enzymes have been identified to be involved in cutin monomer synthesis and polymerization processes, such as glycerol-3-phosphate acyl-transferases 4 and 8 (Li et al., 2007), Bodyguard (Kurdyukov et al., 2006), and Defective in Cuticular Ridges (DCR), a BAHD family enzyme involved in cutin polyester synthesis in Arabidopsis roots, flowers, and seeds. DCR mutant lines are characterized by an almost complete lack of 9 (10),16-dihydroxy-hexadecanoic acid, a major component of the flower cutin polymer, accompanied by several cuticle-associated phenotypic alterations in response to abiotic stresses (e.g. impa...

XAX1 from glycosyltransferase family 61 mediates xylosyltransfer to rice xylan

“…AIR was prepared and analyzed with a HPAEC-PAD as described (21) and in SI Materials and Methods. The extraction of aromatic compounds from AIR was performed as described (55) and in SI Materials and Methods. For the saccharification assay, 5 mg destarched AIR was autoclaved at 120°C for 1 h. A 500-μL enzyme mixture containing 50 mM citrate buffer pH 6.2, 1.6% (wt/vol) tetracycline, 2 μL Ctec2 enzyme mixture (Novozymes), which contains cellulases, β-glucosidases, and hemicellulases, was added and incubated at 50°C for 24 h with shaking.…”

Apoplastic Diffusion Barriers in Arabidopsis

“…In addition, direct transfer of lipids from the ER to the PM has been hypothesized (Kunst and Samuels, 2003). Interestingly, some of the enzymes of the BAHD family, such as DCR and DCF, which are involved in the formation of cutin intermediates, have been localized to the cytoplasm, which necessitates the presence of their substrates in this compartment or at the PM/cytoplasm interface (Panikashvili et al, 2009;Rautengarten et al, 2012). Thus, additional transport mechanisms may be involved (Panikashvili et al, 2009).…”

“…Another member of the BAHD family, DEFECTIVE IN CUTIN FERULATE, which is encoded by DCF (At3g48720), has been implicated in the feruloylation reaction of the lipid polyester cutin. In contrast to other species, the polysaccharide cell wall of Arabidopsis is not feruylated (Rautengarten et al, 2012). The BAHD family member FATTY ALCOHOL:CAFFEOYL-CoA CAFFEOYL TRANSFERASE (FACT) (At5g63560) encodes the enzyme responsible for the synthesis of a subset of alkyl hydroxycinnamate esters, the alkyl caffeates, in root waxes (Kosma et al, 2012).…”

The glycerol-3-phosphate acyltransferase GPAT6 from tomato plays a central role in fruit cutin biosynthesis

“…biosynthesis (Rautengarten et al, 2012). Finally, 11 GDSL lipase genes expressed at various stages of fruit development (Tomato Genome Consortium, 2012; Tomato eFP browser [http://bar.utoronto.ca/ efp_tomato/cgi-bin/efpWeb.cgi]) were expressed at lower levels in gpat6-a.…”