1 Graduate research assistant. 2 Associate professor. 3 Professor emeritus and Jose Fernandez chair for crop production. We thank Cindy Waddell for support in the HPLC analysis, Jose Luis Mendoza, Helen Redden, Melodie Borden, and M.R. Doyle for
Arthur D. Wall, Marisa M. Wall, and Joe N. Corgan
J.G.M. Cutting, D.K. Strydom, G. Jacobs, D.U. Bellstedt, K.J. Van Der Merwe, and E.W. Weiler
Abbreviations: ELISA, enzyme-linked immunosorbent assay; DNOC, dinitro-o-cresol; HPLC, high-performance liquid chromatography; RIA, radioimmunoassay. 1 Present address: Dept. of Horticultural Science, Univ. of Natal, P.O. Box 375, Pietermaritzburg
Susan E. Trusty and William B. Miller
. Current address: Dept. of Horticulture, Clemson Univ., Clemson, SC 29634. We gratefully acknowledge the Fred C. Gloeckner Foundation for HPLC equipment and Yoder Brothers for providing rooted cuttings. We also thank Larry Kasperson for plant care, Della
Richard Grazzini, David Hesk, Ellen Yerger, Diana Cox-Foster, June Medford, Richard Craig, and Ralph O. Mumma
Composition of anacardic acids (phenolic acids known to be associated with small pest resistance in Pelargonium ×hortorum) was examined in 13 diploid and 25 tetraploid cultivars by high-performance liquid chromatography (HPLC). The presence of an unusual desaturation (omega (ω)-5) in the alkyl tail of anacardic acids present only in glandular trichome exudate of pest-resistant diploid inbred lines had previously been associated with a sticky-trap pest-resistance phenomenon. In this study, we examine Pelargonium cultivars for variability in anacardic acid composition to assess the distribution of ω5 desaturation among commercial cultivars, to determine possible interactions between ω5 desaturation and other plant desaturation mechanisms, and to examine the possible impact of ploidy on ω5 desaturation. An unsaturation index (UI) is derived to compare exudates differing widely in composition yet which may provide a similarly effective sticky-trap pest-resistance mechanism based on exudate viscosity. ω-5 Anacardic acids were observed in the glandular trichome exudate of all 38 commercial cultivars examined. No diploid cultivar produced ω5- and ω9- anacardic acids, although the simultaneous production of ω5 and ω9- anacardic acids was observed in three tetraploid cultivars. Total ω5- anacardic acids comprised from 42.4% (tetraploid cultivar Perlenkette-syn. Snowhite, Weiss) to 86.8% (tetraploid cultivar Amanda). Commercial P. ×domesticum cultivars had no ω5 anacardic acids. UIs ranged from 60.9 (tetraploid cultivar Dixieland) to 103.4 (diploid cultivar Pinto White). In contrast, anacardic acids collected from a pest-susceptible inbred line contained no ω5- anacardic acids and had a UI of 38.7. No significant differences among ploidy levels were observed for UIs or for most specific anacardic acid components, with the exception of 24:1 ω5- anacardic acid, in which the mean diploid value (32.1%) was significantly higher than that of the mean tetraploid value (27.6%). We conclude that ω5- anacardic acid production occurs in all Pelargonium cultivars observed and that these cultivars are predicted to exhibit resistance to small arthropod pests. Significant genetic variability in specific anacardic acid composition appears to exist among Pelargonium cultivars, suggesting that breeding for pest resistance can be readily monitored by HPLC of anacardic acids.
Galen Peiser, Gloria López-Gálvez, Marita Cantwell, and Mikal E. Saltveit
. Amrhein for kindly providing a sample of AIP; California Vegetable Specialties, Inc., Dixon, Calif., for providing the Belgium endive; and Betty Hess-Pierce for conducting the HPLC analysis. G. López-Gálvez was a recipient of research grants of NATO and
Theodore J.K. Radovich, Matthew D. Kleinhenz, and John G. Streeter
Ohio Vegetable and Small Fruit Research and Development Program and OARDC Research Enhancement Competitive Grants Program. We thank Dr. Seppo Salminen for his assistance with HPLC analysis, John Elliott, Nate Honeck, Jim Sonowski, and Aparna Gazula for
José A. Narváez, Patricia Flores-Pérez, Virginia Herrera-Valencia, Fernando Castillo, Roberto Ku-Cauich, Blondy B. Canto-Canché, Nancy Santana Buzzy, and Renata Rivera-Madrid
1 To whom reprint requests should be addressed. E-mail address: firstname.lastname@example.org We thank QBB Fabiola Escalante for assistance with the HPLC chromatograms, and also thank Drs. F. Vazquez, Richard Cook, and M
Hendrik van Gorsel and Adel A. Kader
Internal breakdown (IB) is the limiting factor in the storage and postharvest handling of stone fruits. The symptoms of IB appear when fruits are kept for prolonged periods at temperatures below 10C and include leatheriness, mealiness, browning and bleeding of the flesh, and failure to ripen normally. We investigated the changes in phenolic compounds associated with IB of stone fruits. Twenty-eight phenolic compounds were separated by HPLC. Ten of these components were significantly affected by chilling temperatures. The concentration of six phenols changed in response to ripening after chilling temperatures, parallel to the appearance of IB symptoms. Most phenols showed a concentration gradient from the inside to the outside of the fruit, Comparison between peach cultivars showed characteristic differences in phenol metabolism during ripening. In both cultivars the most predominant phenol, chlorogenic acid, showed little change in concentration during storage. The structure of key phenolic compounds will be determined in order to elucidate the biochemical relationship between the phenols and the related enzymes. In this respect, a method was developed to detect phenylalanine ammonia-lyase (PAL) activity in peach fruit.
F.A. Tomás-Barberdán, J. Loaiza-Velarde, and M.E. Saltveit
Mechanical wounding and exposure to ethylene induces an increase in phenylpropanoid metabolism in lettuce and an increase in the concentration of several soluble phenolic compounds that are easily oxidized to brown substances by polyphenol oxidase. To study the early response of lettuce to wounding and ethylene, leaves of iceberg, butter leaf, and Romaine lettuces were either wounded or exposed to ethylene at 10 μL·L–1 in flows of humidified air at 5 or 10°C. Soluble phenolic compounds were extracted at intervals up to 72 hours and were analyzed by HPLC. After 72 hours, wounded leaves of all three lettuce types showed elevated levels of caffeoyl tartaric acid, Chlorogenic acid, dicaffeoyl tartanc acid, and 3,5-dicaffcoyl quinic acid at both temperatures. In contrast, there were no significant increases in soluble phenolic compounds in iceberg lettuce exposed to ethylene at 10°C. At 5°C for iceberg, and at both temperatures for the other two types, there was the same pattern for ethylene treated and wounded leaf tissue. The kinetics of wound and ethylene-induced phenolic metabolism are different and will be discussed in relation to phenolics produced and browning susceptibility.
Joe-Ann McCoy, Mark Widrlechner, and Jeff Carstens
Echinacea is becoming a well-established, high-value crop, both as an ornamental and a dietary supplement. A comprehensive collection of Echinacea germplasm is conserved by the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa, and is available via seed distribution for research and educational purposes (ars-grin.gov/npgs). Representing all nine species collected throughout their respective North American geographic ranges, the Echinacea collection includes 179 accessions. Extensive morphological characterization data associated with this collection have been compiled and are available to researchers on the Germplasm Resources Information Network (GRIN) database to aid in selection criteria. The collection has been used extensively for various research projects, ranging from ornamental breeding studies to HPLC analyses of metabolites of interest to the phytopharmaceutical industry. This poster will summarize the Echinacea collection conserved at the NCRPIS, including a list of available accessions by species, illustrations of seed, and control-pollinated cage propagation methods; and facilities utilized for seed cleaning, testing, and storage. In addition, instructions on how to use the GRIN database to view evaluation data and acquire germplasm will be provided.