Cutin biosynthesis

It is probable that a similar situation exists in cutin biosynthesis in the apple skin slices and excised epidermis of S. odoris, where CytP450-type epoxidase is the biosynthetic enzyme. 

How the aliphatic monomers are incorporated into the suberin polymer is not known. Presumably, activated co-hydroxy acids and dicarboxylic acids are ester-ified to the hydroxyl groups as found in cutin biosynthesis. The long chain fatty alcohols might be incorporated into suberin via esterification with phenylpro-panoic acids such as ferulic acid, followed by peroxidase-catalyzed polymerization of the phenolic derivative. This suggestion is based on the finding that ferulic acid esters of very long chain fatty alcohols are frequently found in sub-erin-associated waxes. The recently cloned hydroxycinnamoyl-CoA tyramine N-(hydroxycinnamoyl) transferase [77] may produce a tyramide derivative of the phenolic compound that may then be incorporated into the polymer by a peroxidase. The glycerol triester composed of a fatty acid, caffeic acid and a>-hydroxy acid found in the suberin associated wax [40] may also be incorporated into the polymer by a peroxidase. 

Li, Y., Beisson, F., Koo, A.J.K., Molina, L, Pollard, M., and Ohlrogge, J. Identification of acyltransferases required for cutin biosynthesis and production of cutin with suberin-like monomers. Proceedings of the National Academy of the United States of America 104, 18339-18344, 2007. 

The lipid transfer proteins (LTPs) are proteins which can be divided into two classes, depending on the molecular weight. In in vitro conditions, it was shown that these proteins are able to transfer phospholipids between cellular membranes (Kader, 1997). The role of LTPs in the process of somatic embryogenesis was shown for the first time in the case of carrot embryos (Sterk et al., 1991). It is postulated that LTPs are involved in cutin biosynthesis and that they can be used as a cellular marker for the development of protodermis in somatic embryos (for a review, see Zimmerman, 1993). LTPs were also found in the extracellular proteins secreted by grapevine somatic embryos (Coutos-Thevenot et al., 1993). In Arabidopsis culture, LTPs were also observed outside the meristematic explant cells, which may indicate that LTPs can be used as a cellular marker during the transition from the somatic to the embryogenic state (Fig. 7). 

The requirement for ATP and CoA suggested that transfer of a hydroxy-acyl group from CoA to the free hydroxyl group of cutin was involved in cutin biosynthesis. Although two pH optima near 7.0 and 8.5 were observed... 

Li H, Pinot F, Sauveplane V, Werck-Reichhart D, Diehl P, Schreiber L, Franke R, Zhang P, Chen L, Gao Y Liang W, Zhang D (2010) Cytochrome P450 family member CYP704B2 catalyzes the co-hydroxylation of fatty acids and is required for anther cutin biosynthesis and pollen exine formation in rice. Plant Cell 22 173-190... 

The aliphatic components of suberin form polyester domains that are attached to the phenolics as indicated above (see Fig. 6.4.7). Activated cu-hydroxy acids and dicarboxylic acids are probably involved in the esterification as shown in cutin biosynthesis (232). It was proposed that the long-chain fatty alcohols found in suberin might be incorporated into the suberin polymer by peroxidase-catalyzed polymerization of phenylpropanoic acid esters of these alcohols (232), such as the ferulic acid esters of C18-C28 alcohols frequently found in suberin-as-sociated waxes (Table 6.4.2). 

The compounds had to be effective in vitro at one or several of the steps of the pathways leading to waxes or cutin biosynthesis, without changing the other chemical activities of the leaf cells. That means that the products had to be selective, in a biochemical point of view... 

The changes in waxes and cutin biosynthesis were measured by incorporating labelled precursors into these cuticle components, which were extracted and submitted to extensive purification afterwards. 

Table 2. Inhibitory effects of Ci2-tr and Cig-tr on waxes and cutin biosynthesis in Vida faba leaves.

Fig. 7. Biosynthesis of cutin monomers, and the polymer from the monomers (inset, bottom left). ACP = acyl carrier protein...

Kolattukudy PE (1981) Structure, biosynthesis and biodegradation of cutin and suberin. In Briggs WR (ed) Annual reviews of plant physiol, vol. 32. Annual Reviews, Palo Alto CA, p 539... 

Kolattukudy PE, Espelie KE (1985) Biosynthesis of cutin, suberin, and associated waxes. In Higuchi T (ed) Biosynthesis and biodegradation of wood components. Academic Press, New York p 161... 

Kolattukudy, P. E. Espelie, K. E. Biosynthesis of Cutin, Suberin and Associated Waxes In Biosynthesis and Biodegradation of Wood Components Higuchi, T., Ed Academic Press New York, 1985 pp. 161-207. 

Kolattukudy, PE. Structure, biosynthesis, and biodegradation of cutin and suberin. Ann. Rev. Plant Physiol, 1981,32, 559-567. 

Cutins - the hard outer layer in many fruit skins -are polymers of C16 and Cis hydroxy acids among which some of the Cis acids also contain a cis epoxy group (Section 2.11). These are intermediates in the biosynthesis of 9,10,18-trihydroxystearic acid from... 

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