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O.T. Chortyk, I.E. Yates and C.C. Reilly

Leaf surface compounds of pecan [Carya illinoensis (Wangenh.) C. Koch] were analyzed with regard to developmental stage and to susceptibility to infection by Cladosporium caryigenum (Ell. et Lang. Gottwald). Immature and mature leaves of two resistant (`Elliott' and `Sumner') and two susceptible (`Wichita' and `Schley') cultivars were extracted with methylene chloride. Extracts were separated by silicic acid chromatography into polar and nonpolar fractions. Constituents of each fraction were subsequently separated by gas chromatography and were identified by gas chromatography-mass spectroscopy. Leaf surface constituents characterized included long-chain aliphatic hydrocarbons, aliphatic wax esters, triterpenoid constituents, aliphatic alcohols, fatty acids, and diacyl glycerides. The predominant surface compounds on immature leaves were lipids such as fatty acids, fatty alcohols, and glycerides. On mature leaves, lipids declined and aliphatic hydrocarbons and triterpenoids became predominant leaf surface constituents. The changes were observed for all cultivars, regardless of genotypic response to C. caryigenum. Thus, we conclude that cuticular chemicals change dramatically during leaf maturation but do not correlate with resistance to scab disease common to certain pecan cultivars.

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Kagiso Given Shadung, Phatu William Mashela and Maboko Samuel Mphosi

as triterpenoids ( Chen et al., 2005 ; Van Wyk and Wink, 2012 ). Cucurbitacin A, which is soluble in water ( Jeffrey, 1978 ), is unstable and readily oxidises to cucumin (C 27 H 40 O 9 ) and leptodermin (C 27 H 38 O 8 ), whereas the insoluble

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Eric A. Curry

Superficial scald is a physiological skin disorder of apples and pears that develops in cold storage and that often increases in severity after the fruit is removed. It is thought to be associated with the accumulation of farnesene in the epithelial tissue. Currently used methods of controlling scald are diphenylamine (DPA) drenches, and controlled atmosphere (CA) to a limited extent. In order to expand the methods available to control scald, we have been investigating the potential of a number of naturally occurring compounds applied to the fruit surface by drenching or by topical application. Fruit were treated either by wiping the fruit surface with technical-grade material and then removing the excess, drenching whole fruit in aqueous emulsions, or drenching fruit in combinations of heat plus emulsion. After treatment, the fruit was air-dried for 30 min and then placed either in regular or CA storage for 6 months, after which time they were placed in a dark room at 68F for 7 days. Scald was evaluated and fruit condition assessed. Results from 3 years indicate farnesene and squalene reduce scald in apples and pears.

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Diana M. Cheng, Gad G. Yousef and Mary Ann Lila

are 20-hydroxyecdysone (20E) and polypodine B ( Grebenok et al., 1991 , 1994 ). Phytoecdysteroids are polyhydroxylated triterpenoids biosynthesized from phytosterols through the mevalonic acid pathway ( Adler and Grebenok, 1999 ). Although the role of

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Yuefang Wang, S. Kristine Braman, Carol D. Robacker, Joyce G. Latimer and Karl E. Espelie

Epicuticular lipids were extracted from the foliage of six deciduous and one evergreen azalea genotypes (Rhododendron sp.) and identified by gas chromatography-mass spectrometry. The relationship of leaf-surface lipid composition with measures of resistance to azalea lace bug, Stephanitis pyrioides Scott, was evaluated. Each genotype had a distinct epicuticular lipid composition. The major surface lipid components from all test taxa were n-alkanes and triterpenoids. In the most resistant genotypes [R. canescens Michaux and R. periclymenoides (Michaux) Shinners] ursolic acid, n-hentriacontane, and n-nonacosane were the most abundant epicuticular lipids. The lipids present in largest proportion among all susceptible deciduous genotypes tested were α-amyrin, β-amyrin, and n-nonacosane. The proportions of the lipid components from the same plant of each genotype varied between spring and fall samples. Among classes of lipids, n-alkanes, n-1-alkanols, and triterpenoids had significant correlations with azalea lace bug behavior on host plants. Among individual components, heptadecanoic acid, n-hentriacontane, oleanolic acid, ursolic acid and one unknown compound (with major mass spectra 73/179/192/284/311) were significantly negatively correlated with host plant susceptibility to azalea lace bug, as measured by oviposition, leaf area damaged, egg and nymphal development, and nymphal survivorship. Triacontanol, α-amyrin, β-amyrin, and three unknowns were significantly positively correlated with host plant susceptibility. Acceptance or rejection by azalea lace bug to a particular plant may be mediated by a balance of positively and negatively interpreted sensory signals evoked by plant chemicals. This study indicated that the high levels of resistance observed in R. canescens and R. periclymenoides may be due to the lesser amount or the absence of attractants and stimulants for feeding or oviposition.

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Yanrong Lv, Ibrahim I. Tahir and Marie E. Olsson

investigation of 247 wild and domesticated apple accessions found that main bioactive compounds, including triterpenoids, had been determined, with the purpose of, e.g., assisting in innovative breeding strategies ( Farneti et al., 2015 ). Due to lack of success

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Andrew L. Thomas, Richard J. Crawford Jr, George E. Rottinghaus, John K. Tracy, Wendy L. Applequist, Besa E. Schweitzer, Larry J. Havermann, Scott F. Woodbury, James S. Miller, Mark R. Ellersieck and Dean E. Gray

continue to increase. The phytochemical content of black cohosh is complex and still inadequately understood; the a.i. and mechanisms of action are not known. Most attention has focused on triterpenoids, which include such compounds as actein, 23-epi-26

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Bhimanagouda S. Patil, G.K. Jayaprakasha and Amit Vikram

., 2003 ), the majority of the studies have used crude extracts to demonstrate the hypo-/antihyperglycemic activity. Furthermore, carotenoids, alkaloids, saponins, and triterpenoids were reported from the bitter gourd ( Chen et al., 2008 ). Carotenoids

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Au Trung Vo, Imane Haddidi, Hussein Daood, Zoltan Mayer and Katalin Posta

. prostrata was first recorded by Holm et al. (1979) and described by Ho (2000) in Vietnam. Some previous studies have confirmed that E. prostrata contains different natural compounds such as flavonoids, alkaloids, triterpenoids, saponins, phenolics

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Maurizio Micheli, Daniel Fernandes da Silva, Daniela Farinelli, Graziana Agate, Rafael Pio and Franco Famiani

tocopherols (with β-sitosterol and γ-tocopherol as the major sterol and tocopherol components, respectively) ( Djibril et al., 2015 ). It also contains vitamin E, phenols, and many triterpenoids of which azadirachtin is the most well known and studied ( Devi