The composition of the cutin of the caryopses and leaves ofTriticum aestivum L.

Abstract

The outer layers (bran) of white wheat (Triticum aestivum L. cv. Jubilar) caryopses contain several layers of lipophilic materials. It was the objective of the present work to establish the nature, composition and amounts of the lipid polymers of wheat bran and to compare it with leaf cutin. Prior to analysis, the bran was isolated and divided into two fractions: (i) the inner bran containing the remnants of the nucellus, the seed coat and the inner layers of the pericarp, and (ii) the outer bran consisting of the peripheral layers of the pericarp. Following depolymerization, a total number of 14 long-chain monobasic, dibasic, ω-hydroxymonobasic, α-hydroxymonobasic, dihydroxymonobasic, trihydroxymonobasic and epoxyhydroxymonobasic alkanoic acids have been identified as constituents of bran lipid polymeres. The most abundant single constituent was 9,10-epoxy-18-hydroxyoctadecanoic acid. The qualitative and quantitative compositions of depolymerisates from the inner and outer bran fractions were similar except for the absence of 9,10,18-trihydroxyoctadecanoic acid and of long-chain (C22-C26 ω-hydroxyalkanoic acids in the outer bran. The composition of bran depolymerisates closely resembled the constitution of the BF3/CH3OH susceptible fraction of wheat leaf cutin. Only less than 2% of the total amount of monomers released from inner bran were indicative for the presence of suberin. The total cutin content of wheat bran amounted to 4.2 g per kg of dry caryopses. Most of it (96.6%) was contributed by the cuticles of the seed coat and the nucellus while the cuticle of the pericarp made up only 3.4%.

A comparative study into the chemical constitution of cutins and suberins from Picea abies (L.) Karst., Quercus robur L., and Fagus sylvatica L.

“…in the outer layers of the caryopses of Triticum; Matzke and Riederer 1990). Then, precise criteria are needed for distinguishing monomers of cutin from those of suberin.…”

“…Data taken and partially recalculated from: 1, Baker and Holloway (1970); 2, Baker and Procopiou (1975); 3, Brieskorn and Binnemann (1975); 4, Brieskorn and Kabelitz (1971); 5, Eglington and Hunneman (1968); 6, Ekman (1983); 7, Ekman and Reunanen (1983); 8, ; 9, ; 10, Espelie et al (1980);11, Franich and Volkman (1982); 12, Hafizoglu and Reunanen (1987);13, Holloway (1972);14, Holloway (1973);15, Holloway (1974);16, Holloway (1982a);17, Holloway (1983); 18, Kolattukudy and Agrawal (1974); 19, Kolattukudy et al (1975); 20, Matzke and Riederer (1990); 21, Pearce and Holloway (1984); 22, Riederer and Sch6nherr (1986); 23, Riederer and Sch6nherr (1988a); 24, Ryser and Holloway (1985);25, Wattendorffand Holloway (1982); 26, Yatsu et al (1983); 27, Espelie et al (1982);28, Holloway et al (1972); 29, this work with chain-length > C2o was calculated as a further variable (C20).…”

Functionality of lipids and lipid-protein interactions in cereal-derived food products

“…These lipids and lipid structures are still widely ignored although they play a significant role in the diffusion of water in plant organs and in the cohesiveness of plant tissues. In cereals seeds, cutin layers could determine the adhesion between aleurone, embryo and starchy endosperm where they are located [3] as it was observed in other plants and plant organs [4][5]. They also form the cuticle layer covering the pericarp (bran) [3] (figure 1).…”

“…In cereals seeds, cutin layers could determine the adhesion between aleurone, embryo and starchy endosperm where they are located [3] as it was observed in other plants and plant organs [4][5]. They also form the cuticle layer covering the pericarp (bran) [3] (figure 1). Since wheat kernels are partially re-hydrated before milling in order to decrease the interactions between bran endosperm and embryo, the cutin layers, in controlling water diffusion, should be also essential to control the interactions between kernel compartments.…”

Probing the cell wall heterogeneity of micro-dissected wheat caryopsis using both active and inactive forms of a GH11 xylanase

“…Cellulose and a small amount of lignins are found in the pericarp, whereas b-glucan is only present in the aleurone wall (Fincher and Stone 1986;Brillouet and Joseleau 1987;Antoine et al 2003). Lipophilic materials are essentially arranged as several polyester-rich cuticular layers (Matzke and Riederer 1990) that are encountered in the epidermis and the testa. Due to their composition, these layers could act as selective barriers in molecule transport (Kolattukudy 1980;Schreiber et al 1999) and protect the grain against pathogenic aggression (Stenvert and Kingswood 1976).…”