Edward A. Baker

Phenolic constituents of tomato fruit cuticles

Abstract Chalconaringenin, naringenin, naringenin-7-glucoside, and m - and p -coumaric acids have been identified in the fruit cuticles of three tomato cultivars. The phenolic content of the cuticles increased substantially during fruit development, those from immature green and mature ripe fruits of cv Ailsa Craig yielding respectively 2.8 and 61 μg/cm 2 (representing 1.4 and 6% of the total membrane wt). Coumaric acids, present only in the ‘cutin-bound’ phenolics, increased from 2 to 24 μg/cm 2 during fruit development. Flavonoids, synthesized mainly during the climacteric, occurred free in the epicuticular (0.3–7.2 μg/cm 2 ) and cuticular (0.7–5.7 μg/cm 2 ) phenolics but the major part of this class of constituents in ripe fruit cuticles was also ‘bound’ to the cutin matrix (30–43 μg/cm 2 ). The composition of the flavonoid fraction was controlled by the spectral quality of incident radiation, red light favouring the formation of chalconaringenin.

The constituent acids of angiosperm cutins

Abstract The composition of the cutin from the cuticles of twenty-four angiosperm leaves and fruits has been compared by GLC. The most abundant acid found in angiosperm cutin is confirmed as 10,16-dihydroxyhexadecanoic with 9,10,18-trihydroxyoctadecanoic occurring frequently and 16-hydroxyhexadecanoic less frequently. Other hydroxy acids, as yet unidentified, have also been found. Monobasic acids, especially hexadecanoic, are important constituents of cutin. Wide variations of cutin composition occur between species, within species and between leaves and fruits of the same species.

Chemical composition and ultrastructure of the epicuticular wax in three lines of Brassica napus (L)

Abstract The epicuticular wax in three lines of Brassica napus (rape) has been investigated and the detailed chemistry and ultrastructure of the waxes examined. A distinct chemical make-up has been found for all three waxes which is correlated with three distinct crystallite structures. A tentative scheme for classification of Brassica wax mutants is described in which the two newly analysed rape mutants can be placed. Mass spectral analysis of all wax components confirms and extends previous ideas about the chemistry of Brassica waxes.

Chemical composition and ultrastructure of the epicuticular wax in four mutants of Pisum sativum (L)

Abstract The action of mutations affecting the epicuticular wax of Pisum sativum has been investigated at the chemical and ultrastructural level. Upper and lower surfaces of the leaves were found to differ markedly in both ultrastructure and chemistry. Mutations affected primarily either the lower (wa, wb and wsp) or the upper surface (wlo), but some effects of all 4 genes could be seen on both surfaces. Specific biochemical lesions could be implied for wsp and wa but the chemical effects of wb and wlo were more diffuse. Generally a close relation between chemical composition and crystallite form of the wax was evident throughout the work.

Branched-chain constituents of Brussels sprout wax

Abstract The presence of a substantial proportion of branched, in addition to normal compounds, was confirmed in the alkyl ester and primary alcohol components

Ontogenetic variations in the composition of peach leaf wax

Abstract The composition of the epicuticular waxes from the adaxial and abaxial surfaces of peach leaves varies considerably during one seasons growth. Triterpenoid acids are major components 84–95% of the waxes from the youngest leaves but the proportions of these constituents decrease as the leaves expand. The waxes from the abaxial surfaces of fully expanded leaves consist primarily of hydrocarbons (C 22–C34 ) and triterpenoid acids, whereas the adaxial surface waxes also contain large proportions of primary alcohols (C 26 -C 34 ) and esters (C 42 -C 52 ). The latter include sitosteryl esters of hexacosanoic, octacosanoic and eicosanoic acids. Variations were also noted between fully expanded leaves of different ages, the abaxial surface waxes of the oldest leaves containing the highest proportions of hydrocarbons, whilst the wax from the adaxial surface of the corresponding leaves contained the largest amounts of esters, sitosterol and hydrocarbons.

Identification of 16-hydroxyoxohexadecanoic acid monomers in plant cutins☆

Abstract The structure of a new hydroxyketo fatty acid which occurs as a major monomer of Citrus limon fruit cutin has been determined by IR, NMR and MS. The monomer was shown to be a mixture of positional isomers of 16-hydroxyoxohexadecanoic acid with the 10-oxo isomer predominating. Substantial amounts of the 9-oxo isomer were present together with smaller quantities of the 8- and 7-isomers. The same compounds were also found to be important constituents of the fruit cutins of Physalis peruviana and Ribes nigrum .

Structure and elemental compositon of grape berry stomata

Summary Former SEM work without cryotechnique of the fruit surface had shown grape (Vitis vinifera L.) berry stomata surrounded by large, conspicuous protuberant tissue. This led to speculation of artifacts resulting from microscopic preparation techniques. This work examined the existance of these alleged protuberances and a possibly distinguished tissue by low temperature scanning electron microsopy (LT-SEM), freezesectioning, energy dispersive X-ray analysis, and light microscopy with staining. LT-SEM showed that peristomatal protuberances of up to 200 Jlm diameter developed two weeks after anthesis in all four grape cultivars examined and consisted of small, compact cells of 10 to 15Jlm length. These cells were distinctly different from the typically larger cells (30-40 Jlm) in the epidermis, hypodermis and outer fruit pericarp. Energy dispersive X-ray analysis revealed no differences in the distribution of sulphur, chlorine and iron between the peristomatal protuberance and non-protuberant tissue. Although potassium concentrations in the peristomatal protuberance were low, silicon and calcium were abundant in marked contrast to the non-protuberant tissue. During the later stages of fruit development, polyphenolics accumulate preferentially in the protuberant tissues and these specialised structures become heavily suberised.

Ultrastructure and chemistry of Clarkia elegans leaf wax: A comparative study with brassica leaf waxes

Abstract The effect of environmental conditions on the chemistry and morphology of Clarkia elegans leaf wax has been examined using gas liquid chromatography and scanning electron microscopy. Chemically the wax consists of a mixture of hydrocarbons, ketones, alkyl esters, aldehydes, primary alcohols and secondary alcohols of which nonacosane, nonacosan-15-one, hexacosyl hexadecanoate and tetracosyl hexadecanoate are the major co wax occurs in the form of smooth films, tubes, dendrites or plates depending upon the growth temperature. A comparison is drawn with the leaf waxes of Brassica species and the findings discussed in relation to the development of epicuticular wax layers.

Identification of the diol associated with variations in wax ultrastructure on Rhus cotinus leaves

Abstract The diol constituent of Rhus cotinus leaf epicuticular wax has been identified as nonacosane-5,10-diol from chemical investigations of the free compound, the TMSi ether and the nonacosane-5,10-dione prepared from the diol by oxidation. The form and distribution of the crystalline waxes changed as the leaves expanded, dense clusters of short tubes covering the thin ribbons formed during the initial stages of growth. The diol content of the wax decreased by more than 50% over the same period.