Epicuticular waxes of two sorghum varieties

The epicuticular waxes of the two sorghum varieties Alliance A and SD 102 have been analyzed, after separation of the leaf blades from the sheaths. The major constituents were found to be free fatty acids but small amounts of esters, aldehydes, alcohols, n-alkanes and sterols were also detected. The typical chain lengths of aldehydes, free alcohols and free fatty acids were C₂₈ and C₃₀.     

Epicuticular wax constituents of North American and European Euphorbia esula biotypes

The epicuticular leaf wax of four North American and one Austrian Euphorbia esula biotypes was examined as a potential source of chemotaxonomic information relative to intraspecies classification. Analysis (GC and GC/MS) shows general similarity of wax constituent character among all biotypes but differences in specific component yields between the North American and Austrian biotypes. Distinctive variation in occurrence of five triterpenes (α- and β-amyrin, δ-amyrenone, 24-methylenecycloartenol and lupeyl acetate) was observed between the North American and Austrian biotypes.     

Effect of drought on phytyl wax esters in Phaseolus leaves

The small amount of phytol which is bound as wax ester in mature bean leaves is increased 10–20 fold by drought. Watering the plants before permanent wilt reverses this trend. Maximum amounts of phytyl wax esters in plants still viable are higher in the drought resistant tepary bean (Phaseolus acutifolius) than in the less resistant garden bean (P. vulgaris).     

Epicuticular wax variability of Juniperus deltoides R.P. Adams from the central Balkan – Ecology and chemophenetics

Juniperus deltoides R.P.Adams is a prickly, evergreen shrub that grows in the East Mediterranean on dry hills and mountains. Needle-like leaves have a thick cuticular layer on the surface, which serves as the ultimate barrier for prevention of water loss. n-Alkanes comprise the biggest part of this hydrophobic wax mixture. These compounds are studied as chemophenetic characters due to their chemical and physiological stability, and strong genetic control. Six central Balkan populations were studied and compared to one eastern and one western. Fifteen n-alkanes were identified, with C33 being dominant in all samples. Univariate and multivariate statistical analyses separated western population from all central Balkan populations, while the eastern Balkan population showed high similarity with the central ones. Climatic, orographic and pedological characteristics of the studied localities were also taken into account.     

白蜡虫几个地方种虫经济性状的比较研究

本文对四川省几个地方种虫的虫囊含卵量、性比、虫囊大小分配情况、100粒虫囊重量、泌蜡期及泌蜡量等经济性状作了比较研究。     

Wax synthesis in Brassica oleracea as modified by trichloroacetic acid and glossy mutations

Two different mutations in Brassica oleracea, gl₅ and gl₄ have been re-investigated using acetate-1-¹⁴C labelling in an attempt to define more closely the nature of the genetic blocks to wax synthesis. It has been found that gl₅ is a mutation which blocks elongation in the Step C₂₈–C₃₀. The mutation gl₄ exhibits no elongation block and could be blocked in the decarboxylation Step C₃₀–C₂₉. 0·1 mM TCA supplied in the culture solution of cauliflower seedlings affected the leaf surface by producing a glossy appearance similar to that induced by gl₃ and gl₄. At this concentration growth was not inhibited and the appearance of the plants was normal except for the surface wax. The amount of surface wax produced was about 40% of that in untreated seedlings on a leaf area basis. Slight, but significant changes in wax composition were noted, mainly involving a reduction in C₃₀ acids and aldehydes, a slight reduction (33–29%) in alkane content, and a marked difference in chain length composition of the alkanes with C₂₇ increased relative to C₂₉. Over a range of concentrations from 0·1–1 mM, TCA inhibited incorporation of label from acetate-1-¹⁴C into C₃₀ acids and aldehydes more than into C₂₈ at concentrations 0·4–0·8 mM while label tended to accumulate in C₂₄ and C₂₆ acids; thus elongation C₂₈–C₃₀ was especially sensitive to TCA. TCA also inhibited incorporation into primary alcohols and esters almost as much as into C₂₉ compounds. In spite of relatively specific effects on incorporation of label into longer chain lengths, the resulting block to C₃₀ synthesis is not sufficient to make much difference to the overall rate of C₂₉ synthesis. Both results of analysis of wax from whole plants and experiments with tissue slices in vitro indicated that the effect of TCA in reducing the glaucousness of the leaf surface is a combination of overall reduction of wax synthesis together with slight but significant changes in wax composition.     

Biogeography of the wax scales (Insecta: Hemiptera: Coccidae: Ceroplastinae)

The modern and native distributions of wax scales are documented and an area cladogram including seventy species is presented. Wax scales are distributed worldwide, but most species are native to either South America or Africa. Their native distribution pattern is discussed in relation to their host-plant specificity and to the dispersal and vicariance theories of biogeography. The vicariance theory is preferred, because the pattern can be explained satisfactorily by plate tectonics but not by dispersal from a centre of origin. The wax scale group probably originated in the combined South American–African continent at least 97 million yr ago.     

Volatiles from the epicuticular wax of watercress (Rorippa nasturtium-aquaticum)

Volatiles from the epicuticular wax of watercress were collected by ether washing and examined using gas chromatographic and mass spectrometric analysi     

p-Hydroxybenzaldehyde as a major constituent of the epicuticular wax of seedling Sorghum bicolor

p-Hydroxybenzaldehyde is present in concentrations up to 30% in the wax of Sorghum bicolor seedlings. It is highly deterrent to locusts, reducing their normal feeding by 90%.     

Wax esters of the new zealand silver fern,Cyathea dealbata

The New Zealand silver fern epicuticular wax contained wax esters (C₃₈–C₆₀) of which the C₄₀–C₅₂ homologues were shown by capillary column GC/MS to comprise C₂₂–C₃₄ even and odd n-alkanols randomly combined with C₁₆–C₂₄ even n-acids.     

Epicuticular waxes of Sorghum and some compositional changes with plant age

Epicuticular wax from mature plants of Sorghum bicolor SD-102 was compared with that from panicles and seedlings of the same variety at the fourth-fifth leaf stage of growth. The composition of wax from SD-102 panicles was quite different from that of mature leaf blades and sheaths. Free fatty alcohols were the dominant class of wax from SD-102 seedlings and C₃₂ was the major homologue of alcohols and aldehydes. For comparison purposes, the epicuticular waxes from whole plants of two other S. bicolor varieties, Alliance A and Martin A, grown up to the tasseling stage, have been analysed. The major wax components were free fatty acids. The typical chain lengths of aldehydes, free alcohols and free fatty acids were C₂₈ and C_30.p-Hydroxybenzaldehyde was not a wax component of the studied varieties of sorghum.     

中国白蜡虫(Ericerus pela Chavannes)泌蜡量研究

通过对我国不同地区繁育的白蜡虫泌蜡实验,表明云南、四川、贵州三省白蜡虫泌蜡量多,其它省区的白蜡虫泌蜡量少。据此建议生产部门在以上三省大力提倡发展白蜡虫生产。     

Absence of long chain aldehydes in the wax of the Glossy II mutant of maize

Wax from the glll mutant of maize lacks aldehydes, which constitute 20 % in the normal genotype. The absence of aldehydes is not associated with a block in the synthesis of alcohols. Moreover in contrast to the wild type, glll wax is characterized by a higher content of C₁₆ and C₁₈ free acids, with a clear defect in the synthesis of C₂₄, C₂₆ and C₂₈ homologues. The results from this study are taken as evidence that the wild type elongation-decarboxylation I (EDI) pathway, leading to the synthesis of all the wax classes of compounds except esters, may be split into an early (EDIa) and a late (EDIb) group of reactions. Mutant glll is apparently defective at the EDIa, governing the synthesis of C₂₄–C₂₈ fatty acyl chains.     

β-Diketones in Rhododendron waxes

Chromatographic, mass spectrometric and spectroscopic evidence has been obtained for four β-diketones occurring in the leaf waxes of some members of     

Epicuticular wax of Triticum aestivum demar 4

The composition of epicuticular wax from plants of bread wheat (Demar 4 variety) at 3 stages of growth was studied. After germination for 30 and 130 da     

Leaf wax of Triticum aestivum

Leaf waxes from spring wheat varieties Selkirk and Manitou contain hydrocarbons (6%, 10%), long chain esters (14%, 13%), free acids (5%, 8%), free alcohols (19%, 21%), β-diketone (16%, 20%), hydroxy β-diketones (8%, 10%), unidentified gum (29%, 16.5%) and minor amounts of diol diesters, glycerides and aldehydes. The major hydrocarbon is nonacosane and major esters are octacosyl esters of C₁₄–C₃₂ acids but C₂₀ and C₂₂ alcohol esters of trans 2-docosenoic and tetracosenoic acids are also present (Selkirk 20%, Manitou 10% of total esters). Previously unknown trans 2-docosen-1-ol is present as an ester (Selkirk 5%, Manitou 2.5% of total esters). Free acids are C₁₄–C₃₂ acids and trans 2-docosenoic and tetracosenoic acids (Selkirk 30%, Manitou 9% of free acids). Octacosanol is the principal free alcohol. Hentriacontane-14,16-dione is the β-diketone and the hydroxy β-diketones are a 1:1 mixture of 8- and 9- hydroxyhentriacontane-14,16-diones.