Grace M. Hunt

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.

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.

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.

Secondary alcohols from Fragaria leaf waxes

Abstract The secondary alcohols isolated from Fragaria leaf waxes and characterised by GC-MS have been shown to be a mixture of isomers of hentriacontanol with the hydroxy substituent on carbons 9, 10, 11 and 12, and of tritriacontanol with the OH group in the 10, 11, 12, 13 and 14 positions, respectively.