Alkyl esters from pinus radiata foliage epicuticular wax

Wax esters from the epicuticular wax of juvenile and mature-tree Pinus radiata foliage have been shown by capillary column GC-MS to consist mainly of short chain (C₆–C₁₂)alkanols esterified with long chain acids (C₂₄–C₃₂) and long chain alkanols (C₂₄–C₃₂) esterified with short chain acids (C₆-C₁₄) in a non-random manner. Mature-tree foliage wax esters also contained nonacosan-10-ol esterified with dodecanoic and tetradecanoic acids.     

Staining Paraffin Sections Without Prior Removal of the Wax

Paraffin sections are usually rehydrated before staining. It is possible to apply aqueous dye solutions without first removing the wax. Staining then occurs more slowly, and only if the embedding medium has not melted or become unduly soft after catting. To avoid this problem, sections are flattened on water no hotter than 45 C and dried overnight at 40 C. Minor technical modifications to the staining procedures are needed. Mercury deposits are removed by iodine, and a 3% solution of sodium thiosnlfate in 60% ethanol is used to remove the iodine from paraffin sections. At room temperature, progressive staining takes 10-20 tunes longer for sections in paraffin than for hydrated sections; at 45 C, this can be shortened to about three times the regular staining time. After staining, the slides are rinsed in water, air dried, dewaxed with xylene, and coverslipped in the usual way. Nuclear staining in the presence of wax was achieved with toluidine blue, O, alum-hematoxylin and Weigert's iron-hematoxylin. Eosin and van Gieson's picric acid-acid fuchsine were effective anionic counterstains. A one-step trichrome mixture containing 3 anionic dyes and phosphomolybdic acid was unsuitable for sections in wax because it Imparted colors that were nninformative and quite different from those obtained with hydrated sections. Advantages of staining in the presence of wax include economy of solvents, reduced risk of overstaining and strong adhesion of sections to slides.     

Isolation of n-paraffins and sec-alcohols from Isotachis japonica

Two homologous series of n-paraffins and sec-alcohols from C₂₀ to C₃₄ or C₃₅ were isolated a wax constituents of a liverwort, Isotachis japonica. In both series, odd-members were predominant compared with even-members: the ratio of the total amount of odd- to total amounts of even-members was 3·9 in the n-paraffin homologues, and 16·5 in the sec-alcohol homologues.     

Composition and structure of secondary fatty alcohols and ketones,isolated from Pyrus malus skin wax

A homologous series of long-chain secondary fatty alcohols from C₂₁ to C₂₉ (C₂₉ being Predominant) has been isolated from the skin wax of a Bulgarian apple variety, Bouhavitsa. The alcohols were found only in a free state. Long-chain fatty ketones, with C₂₉ again markedly prevalent, have been isolated for the first time from the skin wax of this, and another variety, Tetovka. The C₂₉-ketone from both samples was identified by means of MS as nonacosan-10-one. A complete similarity has been found in the relative amounts of C₂₉ in the mixtures of secondary alcohols, ketones and paraffins.     

Micromorphology of epicuticular waxes in Centrosperms

Epidermal surfaces of about 500 species from some 250 genera of centrospermous families plus some possibly related families were examined by scanning electron microscopy. The micromorphology of their epicuticular waxes is described under taxonomic aspects. In general, Centrosperms tend to develop wax platelets on their cuticle. Shape and size of these platelets are highly diverse, but specific for some taxa. Particular forms of rodlets and thick wax plates occur only in few taxa. The systematic and taxonomic applicability of wax micromorphology is limited, but tentatively family characterizations are given. The data presented provide additional information concerning the familiar and suprafamiliar classification ofCaryophyllales. Dedicated to the enthusiast of succulent Centrosperms, Prof. DrK. E. Wohlfarth-Bottermann (Director of the Institute of Cytology and Micromorphology, University of Bonn) on the occasion of his 65th birthday in May 1988.     

The effect of plant surface characteristics on resistance of rice to the brown planthopper, Nilaparvata lugens

Increased activity of the brown planthopper, Nilaparvata lugens (Stål) on rice variety IR46 over that observed on varieties IR22 and IR62 was shown to be due to the chemical composition of the surface wax. Reduced settling and probing of the plant surface after exploration, and a tendency to move off the stem onto the leaves as a result of chemical cues from the wax make this a potentially important resistance mechanism in rice. Bioassays have shown that the effect is caused by the hydrocarbon- and carbonyl-containing fractions of the wax of IR46. An investigation of N. lugens behaviour on initial contact with the surface of several other varieties of rice has indicated a similar effect for IR36, and a much stronger effect with the wild rice WR221.

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Résumé La composition de la cire superficielle s'est révélée la cause de l'accroissement de l'activité de N. lugens sur la variété de rix IR46, par rapport aux variétés IR22 et IR62. Un mécanisme important de la résistance potentielle du riz est dû aux conséquences des caractéristiques chimiques de la cire: établissement et sondage de la plante réduits après exploration, et tendance à quitter la tige pour gagner les feuilles. Des expériences ont montré que ces effets étaient provoqués par les fractions de la cire de IR46 contenant des hydrocarbures et des carbonyls. L'étude du comportement de N. lugens, lors du premier contact avec la surface de plusieurs autres variétés, a montré un effet semblable pour IR36 et un effet beaucoup plus fort avec le riz sauvage WR221.

     

Trialkyltrioxanes in flower wax of some decorative roses

The polymeric form in which long-chain aliphatic aldehydes are present in rose flower waxes has been established as the 2,4,6-trialkyl 1,3,5-trioxane.     

Multiple controls for the variability of hydrogen isotopic compositions in higher plant n-alkanes from modern ecosystems

We performed a global scale analysis of available leaf wax n -alkane δ D data compiled from our new results, as well as from the literature and expressed as average values of D/H ratios from three common lipids of n -alkanes with odd carbon numbers ( n -C₂₇, n -C₂₉, and n -C₃₁) from living higher plants. Our results clearly indicate multiple controls of hydrogen isotope composition and its variability in plants leaf wax. (1) At the global scale, precipitation δ D values play a dominating factor that exercises the first order of control for hydrogen isotopic compositions in plant leaf wax. The hydrogen isotopic composition of plant leaf wax tracks the decreasing trend of precipitation δ D with increasing latitude. (2) Because of different water acquisition systems, plant life form influences the hydrogen isotopic composition of leaf wax n -alkanes with woody plants and grasses having different responses to the change of global precipitation δ D. (3) Physiological difference, due to different photosynthesis pathways or different water usage strategies, can leave an imprint on δ D patterns of plant leaf waxes, causing δ D variations among plants using the same source water. While these results better explain the variability of hydrogen isotope composition in leaf wax, they also have important implications for the interpretation of n -alkane δ D data from fossils and ancient sediments.     

Biosynthesis of pentacyclic triterpenoids in leaves of Ilex aquifolium L.

Ilex leaves can utilize sucrose and mevalonate for the synthesis of triterpene esters. Mevalonate is also used for the synthesis of free triterpenoid alcohols, but sucrose is not. The selectivity of precursor utilization indicates separate sites for triterpenol and triterpenol-ester synthesis. The sites of synthesis are not found at the main locations of accumulation of triterpenols (the epicuticular wax) or triterpene esters (the cytoplasmatic lipid globules). Transport from the site of synthesis to the lipid globules, and especially towards the epicuticular wax, is slow.Abbreviations MVA mevalonic acid lactone - TLC thin layer chromatography