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Zhanyuan Du and William J. Bramlage

Ethephon and diphenylamine (DPA) were used to examine the role of ethylene production in biochemical changes that precede development of superficial scald on `Cortland' apples (Malus domestica Borkh.) after cold storage. Treatments modified α-farnesene and conjugated triene (CT) accumulations in fruit peel, and their effects on CTs differed depending on whether CTs were measured at 258 nm (CT258) or 281 nm (CT281). Ethephon induced rapid and delayed effects on fruit, the former being stimulation of ethylene production and α-farnesene and CT accumulation in fruit peel, which could increase scald development, and the latter being a disproportionately higher accumulation of CT258 than of CT281 during prolonged cold storage, which was associated with reduced scald development. DPA treatment at harvest also produced rapid and delayed effects. It immediately reduced ethylene synthesis and α-farnesene and CT accumulation. In addition, during fruit storage at 0C, DPA reduced accumulation of CT281 more than that of CT258. The rapid and delayed effects of DPA should contribute to less scald development. These results showed that ethylene probably was involved in effects of ethephon and DPA on scald development and suggest that ethylene has a fundamental role in changes associated with superficial scald development.

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Yin Xu, Yizhou Ma, Nicholas P. Howard, Changbin Chen, Cindy B.S. Tong, Gail Celio, Jennifer R. DeEll, and Renae E. Moran

Soft scald is a chilling-related, abiotic disorder of apple and pear ( Pyrus communis L.) fruit in which the peel develops soft, brown, sunken lesions, but the interior initially looks fine ( Brooks and Harley, 1934 ). The fruit flesh may

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Jinhe Bai, Xinhua Yin, Bruce D. Whitaker, Kristi Deschuytter, and Paul M. Chen

Superficial scald is a major physiological disorder of ‘Anjou’ pears that occurs after ≥3 or 5 months of cold storage in air or controlled atmosphere (CA), respectively ( Hansen and Mellenthin, 1979 ). The commercial air storage target for ‘Anjou

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Theo Solomos, Prabodh Trivedi, and Mehar Asif

We have studied scald development by comparing changes in gene expression, C2H4 evolution, and α-farnesene and conjugated trienol contents in scald-resistant cultivars, i.e., `Gala' and `Braeburn', and scald-sensitive cultivars, i.e., `Red Delicious' and `Granny Smith'. We also carried out similar comparisons between controls and treatments that diminished scald symptoms in sensitive cultivars. The data show that scald development is critically dependent on the initiation of the climacteric rise in C2H4 evolution, since treatments that suppress the latter inhibit scald development at low temperatures coincident with a suppression of α-farnesene and conjugated trienols. However, in scald-resistant cultivars, there is an increase in α-farnesene and conjugated trienols, although to a lower degree than in the sensitive cultivars. This indicates that factors other than the auto-oxidation of α-farnesene are also involved in scald development. Analytical data show that malonyl dialdehyde (MDA) increases only in scalded areas, which, in turn, suggests that oxidative reactions are involved in scald development. Storage of `Granny Smith' at temperatures above 7 °C prevents the development of scald without affecting the accumulation of α-farnesene and conjugated trienols. This in turn suggests that chilling temperatures induce as yet unknown enzymes that contribute to scald development. In short, the data show that in addition to cultivars, low temperature stress and the induction of the C2H4 climacteric play a crucial role in scald development. Preliminary data show that treatment of `Granny Smith' apples with olive oil emulsions suppress scald development symptoms.

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Jennifer R. DeEll and Behrouz Ehsani-Moghaddam

flavor characteristics and can remain crisp for at least 6 months in cold storage ( Tong et al., 1999 ). Unfortunately, ‘Honeycrisp’ is also extremely susceptible to the storage disorders soft scald and soggy breakdown ( Tong et al., 2003 ; Watkins et al

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Renae E. Moran, Jennifer R. DeEll, and Dennis P. Murr

‘Honeycrisp’ apples develop the disorders soft scald and soggy breakdown in cold storage, particularly at temperatures below 3 °C ( Watkins et al., 2003 ). Soft scald is a low-temperature disorder that is characterized by sharply defined

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Rachel Leisso, Ines Hanrahan, and Jim Mattheis

success, including soft scald ( El-Shiekh et al., 2002 ; Tong et al., 2003 ). Soft scald is characterized by sharply demarcated irregular large brown lesions on fruit peel where tissue is slightly sunken and less firm (soft) to the touch ( Plagge and

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Cynthia L. Barden and William J. Bramlage

During the harvest season apples ripen and develop scald resistance. In the Northeast they usually are also exposed to cool temperatures as they mature and ripen. Experiments were conducted to study the effects of cool temperature, light and maturity on the endogenous antioxidants and subsequent scald development in Cortland and Delicious apples. Total lipid-soluble antioxidant activity in apple peel at harvest generally increased as scald incidence after storage decreased. Yet, α tocopherol, ascorbic acid and total water-soluble reducing capacity were not closely related to scald development. The absence of light (bagged fruit) decreased all measured antioxidants and increased scald development. However, ethephon applied in mid-August to induce ripening increased the levels of these antioxidants but had little effect on scald incidence in the absence of cool temperatures (hours <10°C). Cool temperatures, which decreased scald susceptibility, increased lipid-soluble antioxidant activity but had little influence on the other measured antioxidants. These data suggest that the endogenous antioxidants may be only partly responsible for natural scald resistance.

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S. Wee and R.M. Beaudry

Autoxidation products alpha-farnesene of have been implicated in superficial scald induction for apple (Malus domestica cv. Cortland Apple) fruit. We suspect the apple cuticle acts as a sink where α-farnesene can accumulate and eventually autoxidize into hydroperoxides, conjugated trienes, 6-methyl-5-hepten-2-one (ketone), and other compounds. These oxidized byproducts may diffuse back into the peel, thereby initiating the scald process. Cortland apples were stored at 0.8°C. Volatile cuticular components were analyzed at 2-week intervals by gas chromatography–mass spectroscopy. Only two scald-related volatiles were found, 6-methyl-5-hepten-2-one and α-farnesene. The identification of these compounds may allow the determination of cuticular involvement in superficial scald, as well as a possible correlation between the volatiles and apple scald development. α-farnesene concentrations initially increased and was followed by a decline, possibly due to its autoxidation.

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Renae E. Moran, Jennifer R. DeEll, and William Halteman

‘Honeycrisp’ is a popular cultivar that is currently being planted in large numbers in northern regions of the United States and Canada. ‘Honeycrisp’ is highly susceptible to soft scald, a chilling disorder characterized by sharply defined browning