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J.C. Goffreda, J.C. Steffens, and M.A. Mutschler

Behavioral studies have shown that aphid resistance in Lycopersicon pennellii (Corr.) D'Arcy is due to the presence of sugar esters in glandular exudate of the type IV trichomes. In this study, various methods for the estimation of epicuticular sugar ester concentrations were examined. There was a significant negative relationship between the concentration of sugar esters on the leaf and the level of potato aphid infestation in a segregating L. esculentum × L. pannellii F2 population. Selection for sugar ester accumulation should be an efficient selection technique for the aphid resistance of L. pennellii and other species that synthesize epicuticular sugar esters.

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Thomas J. Molnar, Joseph C. Goffreda, and C. Reed Funk

Anisogramma anomala (Peck) E. Müller is the causal agent of the disease eastern filbert blight (EFB) of hazelnuts (Corylus spp.). Little is known of its genetic diversity and pathogenic variation. Most sources of host resistance have been identified in the Pacific Northwest, a region outside the native range of A. anomala believed to have limited diversity of the fungus due to a long history of quarantine and its relatively recent inadvertent introduction. In an attempt to investigate the pathogenic variation of A. anomala, 12 hazelnut genotypes that showed complete resistance in Oregon were inoculated with 12 isolates collected from across its native range. At the conclusion of the study, ‘Grand Traverse,’ ‘Ratoli’, OSU 541.147, OSU 495.072, and OSU 526.041 remained free of disease. ‘Closca Molla’, OSU 759.007, and OSU 587.044 were infected by most isolates. ‘Gasaway’ was infected by the Michigan isolate, which was also the only one to infect its offspring ‘Zimmerman’, although the lesion lacked sporulating stromata. Interestingly, ‘VR20–11’, another offspring of ‘Gasaway’, was infected by isolates from New Jersey, Minnesota, and Michigan. The Michigan isolate also caused the only signs of infection on OSU 408.040.

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Thomas J. Molnar, Sara N. Baxer, and Joseph C. Goffreda

An eastern filbert blight resistance screening technique was developed that reduces the time required to identify susceptible Corylus avellana L. seedlings from the previously reported 14 to 16 months after inoculation to 6 to 7 months. To accomplish this, hazelnuts were harvested at maturity, treated with GA3, germinated, and grown for about 8 weeks at 24 °C day/18 °C night with 16-hour daylengths. Seedlings were then moved to a humidity chamber and inoculated with ascospores of Anisogramma anomala (Peck) E. Müller 3 times over 2 weeks by misting until run off with a solution of 1 × 106 ascospores/mL in sterile distilled water. Following inoculation, seedlings were returned to the original greenhouse for 8 weeks and then were moved to a 10 to 15 °C day/5 to 10 °C night greenhouse with natural daylengths for 4 weeks. They were then moved to a 4 °C cold room for 8 weeks to receive chilling. Afterwards, seedlings were returned to a greenhouse at 24 °C day/18 °C night where stromata development was visible in 4 to 6 weeks.

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Christopher D. Gussman, Joseph C. Goffreda, and Thomas J. Gianfagna

Ethylene production and fruit softening during postharvest storage of several apple (Malus domestica Borkh.) ripening variants were compared with two standard cultivars. PA14-238 and D101-110 produced only low levels of ethylene (<10 μl·kg–1·hour–1) at harvest and throughout most of 86 days of storage at 4C, whereas `Red Chief Delicious' and `Golden Delicious' fruit produced >100 μl ethylene/kg per hour during the same time period. PA14-238 and D101-110 flesh disks converted aminocyclopropane-1-carboxylic acid (ACC) but not methionine (MET) to ethylene. `Red Chief Delicious' readily converted both MET and ACC to ethylene at the end of cold storage. PA14-238 fruit were the firmest and did not soften during postharvest storage; however, D101-110 softened appreciably. NJ55 did not produce ethylene at harvest, but produced a significant amount of ethylene (90 μl·kg–1·hour–1) during storage. Despite its high capacity to produce ethylene, NJ55 remained nearly as firm as PA14-238 at the end of cold storage.

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Thomas J. Molnar, David E. Zaurov, Joseph C. Goffreda, and Shawn A. Mehlenbacher

Six hundred five hazelnut (Corylus avellana L.) seedlings from a diverse germplasm collection made in the Russian Federation and the Crimean peninsula of the Ukraine were inoculated with the eastern filbert blight (EFB) pathogen Anisogramma anomala (Peck) E. Müller and their responses evaluated. Responses were rated on a scale of 0 to 5, in which 0 represents no sign of EFB and 5 represents all branches exhibiting cankers. At final evaluation, eight seedlings showed no signs of the pathogen or symptoms of the disease. Five additional seedlings expressed only very minor signs of the pathogen (rating = 1). The remainder ranged in disease expression from moderately to severely infected to dead with 89.7% (470 of 524) of the surviving seedlings rating 4 or 5. Of the 13 apparently resistant seedlings (rating 0 or 1), seven originated from nuts purchased from roadside vendors near Simferopol, Crimea, Ukraine; five from nuts purchased at an outdoor market near Krasnodar, Russia; and one from nuts obtained from the hazelnut breeding program of the Nikita Botanical Gardens, Yalta, Crimea, Ukraine. Random amplified polymorphic DNA (RAPD) markers generated by the primers UBC 152800 and OP AA12850, which are tightly linked to the single dominant resistance gene ‘Gasaway’, were not present in all 13 resistant seedlings, providing support, along with their geographic origins, that they represent novel sources of genetic resistance to EFB.

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Ravza F. Mavlyanova, Faizulla Kh. Abdullaev, Payzillo Khodjiev, David E. Zaurov, Thomas J. Molnar, Joseph C. Goffreda, Thomas J. Orton, and C. Reed Funk

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Valery N. Yezhov, Anatoly V. Smykov, Vladimir K. Smykov, Sergei Yu. Khokhlov, David E. Zaurov, Shawn A. Mehlenbacher, Thomas J. Molnar, Joseph C. Goffreda, and C. Reed Funk

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Mirmahsud M. Mirzaev, Uri M. Djavacynce, David E. Zaurov, Joseph C. Goffreda, Thomas J. Orton, Edward G. Remmers, and C. Reed Funk

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David E. Zaurov, Thomas J. Molnar, Sasha W. Eisenman, Timothy M. Ford, Ravza F. Mavlyanova, John M. Capik, C. Reed Funk, and Joseph C. Goffreda

Central Asia is a center of diversity for many important fruit and nut tree species, including wild and cultivated apricots (Prunus armeniaca L.). A wealth of apricot germplasm that expresses novel and valuable characteristics such as fruits with high soluble solids, edible kernels, glabrous skin, and diverse colors and flavors, as well as later-blooming flowers, late-maturing fruit, and drought, cold, and salt tolerance, can be found growing across this region. Since the dissolution of the Soviet Union, Central Asia has become more accessible for reciprocal germplasm exchange and scientific collaborations. Thus, opportunities now exist to obtain, study, and use a much wider diversity of Central Asian apricot germplasm in breeding efforts, which can lead to improved crop traits and ultimately an expansion of the regions where this high-value crop can be grown. To bring attention to the valuable P. armeniaca genetic resources found in Central Asia and to promote its better use, management, and preservation, a description and history of the species from a Central Asian perspective, along with recent and ongoing activities, are discussed in this article.