Roger A. Andersen

Optimum conditions for bonding of plant phenols to insoluble polyvinylpyrrolidone

Abstract Maximum bonding of the principal plant phenols ofNicotiana tabacum to insoluble polyvinylpyrrolidone occurred at pH 3·5 in 1–10 per cent methanol. Three successive additions of 0·5 g each of purified polyvinylpyrrolidone quantitatively bound 100 μg amounts of each phenol. The bonding was reversible; 8 M urea, 5 M guanidine hydrochloride andN-methyl-2-pyrrolidone released undegraded caffeic acid from the polyvinylpyrrolidone-caffeic acid insoluble complex. The analytical and spectral data presented in this paper indicate that the phenols were attached to the polyvinylpyrrolidone principally by hydrogen bonds.

Effects of some natural volatile compounds on the pathogenic fungiAlternaria alternata andBotrytis cinerea.

A bioassay system was developed to test the effects of volatile compounds on the growth of hyphae from germinating fungal spores. Volatiles from crushed tomato leaves inhibited hyphal growth of two fungal pathogens,Alternaria alternata andBotrytis cinerea. Aldehydes, including C6 and C9 compounds formed by the lipoxygenase enzyme pathway upon wounding leaves, inhibited growth of both fungal species. Terpene hydrocarbons, 2-carene and limonene, had no significant effect on hyphal growth. The quantities of volatile compounds in the vapor phase of the bioassay system were measured by direct headspace sampling and GC analysis.

Volatiles from flowers of Nicotiana sylvestris, N/ Otophora and malus × domestica : headspace components and day/night changes in their relative concentrations

Abstract Headspace components from the flowers of Nicotiana otophora and apple (Malus × domestica) were trapped on Tenax and identified by GC and GC-MS. Aromatic compounds from phenylpropanoid metabolism including benzyl alcohol were predominant as was shown earlier for Nicotiana sylvestris. Studies of diurnal emissions of identified volatiles from these species showed there was a marked increase (ca 10 fold) in aromatic compounds released from N. sylvestris inflorescences in situ at night compared to day. Marked diurnal changes in compounds from other biosynthetic pathways were not observed. Emissions of benzyl alcohol and other phenylpropanoid derived volatiles did not increase at night in inflorescences of N. otophora or flowering branches of apple, respectively. Aromatic compound emissions from N. sylvestris at 90 min intervals were determined over a 24 hr period using a purge and trap GC system for analyses. The aromatics were at relatively low levels after midday but subsequently increased to reach peak emissions around 2–3 a.m. followed by declines in these levels of emissions. Possible functions for the dark period enhanced emission of volatile aromatic compounds are discussed.

Accumulation of capsidiol in tobacco cell cultures treated with fungal elicitor

Abstract Addition of fungal elicitor to tobacco cell suspension cultures induced extracellular accumulation of capsidiol.

Glycosidically bound volatile components of Nicotiana sylvestris and N. Suaveolens flowers

Abstract Glycosidically bound volatile components were extracted from flowers of Nicotiana sylvestris and N. suaveolens and isolated using liquid column chromatography with an Amberlite XAD-2 resin. These glycosides, which were putative precursors of fragrance compounds, were hydrolysed enzymatically and a number of the volatiles released were subsequently identified by GC-MS including compounds not previously identified in the floral headspace of these species. Average yields of volatiles released from glycosides were ca 230 and 1050 μg g −1 for N. sylvestris and N. suaveolens flowers, respectively. Compounds in the glycosidically bound fraction were all phenylpropanoid-derived volatiles (e.g. benzyl alcohol, benzaldehyde, E -cinnamyl alcohol, benzyl salicylate) with the exception of the monoterpene α-terpineol. No pronounced diurnal changes in the levels of glycosidically bound volatile compounds could be noted from flowers of either species. However, pronounced differences were obtained in the concentrations of glycosidically bound volatiles at different floral maturity stages.

Strawberry foliage headspace vapor components at periods of susceptibility and resistance toTetranychus urticae Koch

Headspace components from strawberry foliage have been isolated by nitrogen entrainment and Tenax trapping. Traps were eluted with hexane, and components were analyzed by gas chromatography-mass spectrometry. Fifteen compounds were identified by comparison with authentic standards,trans-2-hexenal, 1-hexanol,trans-2-hexen-1-ol,cis-3-hexen-1-ol, hexyl acetate,cis-3-hexenyl acetate, 6-methyl-5-hepten-2-ol, 1-octanol, 1-octen-3-ol, linalool, α-terpineol, methyl salicylate, ethyl saiicylate, benzyl alcohol, and 2-phenylethanol. The relative amounts of these components were compared at flowering and after fruit harvest when plants were more resistant to the two-spotted spider mite,Tetranychus urticae Koch. The predominant components,cis-3-hexen-1-ol and its acetate, did not change markedly between the sampling periods, but methyl salicylate increased approximately 10-fold after fruit harvest. Methyl salicylate at low concentrations under bioassay conditions did not affect mite behavior. The biosynthetic relationship of this compound to other phenols which have been implicated in plant resistance is discussed.

The Impact of Alteration of Polyunsaturated Fatty Acid Levels on C6-Aldehyde Formation of Arabidopsis thaliana Leaves

C6-aldehydes are synthesized via lipoxygenase/hydroperoxide lyase action on polyunsaturated fatty acid (PUFA) substrates in plant leaves. The source pools and subcellular location of the processes are unknown. A close relationship is found between the composition of PUFA and the composition of C6-aldehydes. In the current study, this relationship was tested using the Arabidopsis PUFA mutant lines act1, fad2, fad3 fad5, fad6, and fad7. The results indicate that C6-aldehyde formation is influenced by the alteration of C18 PUFA levels. Mutants act1 and fad5, which are deficient in C16 unsaturated fatty acids, had wild-type levels of C6-aldehyde production. Mutants deficient in the chloroplast hexadecenoic acid/oleic acid desaturase (fad6) or hexadecadienoic acid/linoleic acid desaturase (fad7) had altered C6-aldehyde formation in a pattern similar to the changes in the PUFA. Mutations that impair phosphatidylcholine desaturase activity, such as fad2 and fad3, however, resulted in increased E-2-hexenal formation. The enzymes involved in C6-aldehyde production were partially characterized, including measurement of pH optima. The differences in C6-aldehyde formation among the fatty acid mutants of Arabidopsis appeared not to result from alteration of lipoxygenase/hydroperoxide lyase pathway enzymes. Investigation of the fatty acid composition in leaf phospholipids, glycolipids, and neutral lipids and analysis of the fatty acid composition of chloroplast and extrachloroplast lipids indicate that chloroplasts and glycolipids of chloroplasts may be the source or major source of C6-aldehyde formation in Arabidopsis leaves.

Volatile compounds from triticum aestivum

Abstract Volatile compounds were isolated from aerial parts (foliage and culms) of wheat plants by reduced pressure steam distillation-extraction and identified by gas chromatography-mass spectrometry and co-chromatography with authentic compounds. Infrared spectra were also obtained on some constituents. Compounds identified included nonanal and related unsaturated C9 aldehydes and alcohols as major components and some additional aldehydes, alcohols and a ketone.

Effect of diurnal sampling on the headspace composition of detached Nicotiana suaveolens flowers

Abstract Compounds emitted over a 24 hour sampling period by detached flowers of Nicotiana suaveolens were examined after collecting flowers at 12:00 and 24

Effects of near-ultraviolet radiation and temperature on soluble phenols in Nicotiana tabacum

Abstract Low levels of near-ultraviolet radiation (300–400 nm) along with the visible radiation during the daily illumination periods resulted in tobacco ( Nicotiana tabacum L.) plants with about twice the concentrations of total soluble phenolics and chlorogenic acid isomers present in leaves of tobacco that did not receive near-u.v. radiation. Plants grown at 24° had about 150 per cent of the total soluble phenolic concentrations contained in plants that received the same quality of light, but were maintained at 32°.