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  • Author or Editor: A. Kramer x
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Abstract

Headspace gas chromatographic analyses were made on 6 cultivars of carrots during 1, 7, 16, and 26 weeks of storage at 45°F and 90% RH. Peak heights were used as indicators of volatile concentrations. Profiles significantly differed among cultivars at 8 peak heights, and among storage durations at 6 peaks. Thus, gas chromatographic profiles may be useful in distinguishing carrot cultivars and in determining their residual storage life. The data were analyzed by IBM 7094 Computer using the BMDO-2v Program for factorial design.

Open Access

Fruit of highbush blueberry (Vaccinium corymbosum L.) produce antimicrobial volatiles, including trans-2-hexenal, that may confer resistance to anthracnose fruit rot, an important postharvest disease caused by Colletotrichum acutatum J.H. Simmonds. To investigate whether aromatic volatiles in highbush blueberry fruit are associated with postharvest fruit rot resistance, we compared volatiles emitted from whole fruit and extracts from fruit kept in air at 20 °C for 0 to 6 days postharvest from cultivars having a wide range of resistance to anthracnose. Antimicrobial volatiles detected included the aldehydes, trans-2-hexenal and hexanal; the monoterpenes, limonene, linalool, 8-hydroxylinalool, α-terpineol, and terpinyl acetate; and the sesquiterpenes, cadinene, caryophyllene, and α-farnesene. There were significant correlations between some detected volatiles and these differed in whole fruit and extracts. Hexanal (in fruit extracts), trans-2-hexenal, terpinyl acetate, and cadinene emissions increased in most cultivars when fruit were kept in air at 20 °C for various times postharvest. Volatile emissions from whole fruit and extracts varied widely among the cultivars with early ripening cultivars generally showing higher volatile emissions than later ripening cultivars. Although the cultivars tested differed in quantities, and in some cases, the types of volatiles produced, these differences were not related to pedigree (i.e., species composition) nor to known anthracnose resistance ratings. Except for the confounded emissions of terpinyl acetate and cadinene, more than 80% of the variation observed for each volatile was attributable to the cultivar (genetic), year (environmental), and cultivar–by-year interaction. The results suggest that, although antimicrobial aldehydes and terpenes emitted from fully ripe highbush blueberry fruit and extracts might be important flavor and aroma components, they do not significantly contribute to disease resistance against anthracnose fruit rot.

Free access

Tropane alkaloids (TA) are compounds widespread in the Solanaceae family. The genera Atropa, Brugmansia, Hyoscyamus, and Scopolia, produce the pharmaceuticals hyoscyamine (Hy) and scopolamine (Sc), which are valued for their antimuscarinic and anticholinergic actions. The enzyme hyoscyamine 6β-hydroxylase (H6H) (EC 1.14.11.11) catalyzes both the hydroxylation of hyoscyamine to 6β-hydroxyhyoscyamine and the epoxidation of the latter, leading to scopolamine (Hashimoto et al. ). During the examination of three genes in the TA biosynthetic pathway, the first committed step, the path branch point, and the final step in 13 accessions of Hyoscyamus niger from North America and Europe, genetic variations were found to be absent except in the h6h gene locus (GenBank: D26583.1). Quantification of TA showed average concentrations of 26 to 520 μg/g of dry leaf tissue among the accessions. From a monohybrid cross of the expected (Pennsylvania accession Ames 3103, aa) and novel (Netherlands accession PI 641691, bb) genotypes, the F2 population (n = 104) leaf and root tissues were extracted, analyzed for Hy and Sc contents, and compared with the h6h genotypes (aa, ab, bb). The polymorphism showed Mendelian inheritance. The presence of the polymorphic gene bb showed a marginally significantly greater concentration of hyoscyamine in the leaf tissue (P = 0.0675) and significantly greater concentration in root tissue (P = 0.0436), along with increased concentration of scopolamine in the root tissue (P = 0.0494) compared with the aa genotype. The increase in overall TA in the root tissue of the genotype bb was accompanied by a reduction in scopolamine in the foliar tissue. The 694-bp b amplicon has been sequenced for comparison with the expected 550-bp a amplicon and can be a useful enzymatic variant for TA metabolic engineering.

Open Access

Abstract

Hexamethylenediamine adipate and the half amide of glutaric acid and hexamethylenediamine are biodegradable N-containing compounds with soil flocculating properties. Hexamethylenediamine adipate added to soil medium prior to sowing improved germination of tomato (Lycopersicon esculentum L. cv. Manapal.)

Open Access

Prestorage infiltration of `Golden Delicious' apples (Malus domestica Borkh.) with calcium (Ca) retarded texture changes during storage at 0C and inhibited ethylene production of the fruit at 20C. Infiltration of the fruit with the polyamines (PA) putrescine (PUT) or spermidine (SPD) also altered texture changes, but did not inhibit ethylene production. When the fruit were treated with Ca first and then with PA, cell wall-hound Ca concentrations increased 4-fold, but PA levels in the cell wall increased only slightly. When the fruit were treated with PA first and then with Ca, PA levels in the cell wall increased 3-fold, but Ca concentration increased only 2-fold. These results indicate that Ca and PA may he competing for the same binding sites in the cell wall and that the improvement of fruit quality during storage by these cations could involve strengthening of the cell wall.

Free access

Cucumis sativus L. (cvs. Poinsett and Ashley) plants were grown from seed in a growth chamber at a +10C (28/18) or a -10C (18/28) difference (DIF) between day temperature (DT) and night temperature (NT) on a 12-hour photoperiod for 24 days prior to ozone (O3) fumigation (3 hours at 0.5 umol·mol-1). Negative DIF, compared to +DIF, reduced plant height, node count, fresh weight, dry weight, and leaf area in both cultivars. Photosynthetic rate (Pn), chlorophyll concentration, and variable chlorophyll fluorescence (Fv) were lower and O3 injury and polyamine concentrations were higher at -DIF than at +DIF. Ozone fumigation generally increased leaf concentration of polyamines and reduced Pn, stomatal conductance, and chlorophyll fluorescence. `Poinsett' generally had a higher specific leaf mass and higher concentrations of chlorophyll a and polyamines than did `Ashley', but there was no cultivar difference in O3 injury, growth response, Pn, or stomatal conductance.

Free access