scholarly journals Intermittent Warming Effects on Superficial Scald of Apple Fruit

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 605b-605
Author(s):  
Thair F. Alwan ◽  
Christopher B. Watkins
Keyword(s):  
Fruit Ripening ◽  
Marked Reduction ◽  
Apple Fruit ◽  
Oxidation Products ◽  
Superficial Scald ◽  
Cooperative Agreement ◽  
Postharvest Treatments ◽  
Conjugated Trienes ◽  
Hexane Extracts ◽  
Intermittent Warming

Fruit of `Cortland', `Delicious' and `Law Rome' were warmed for 24 hours at 20°C either weekly, once every 2 weeks, or once every 3 weeks during storage. The effect of these treatments on fruit ripening and concentrations of alpha-farnesene and conjugated trienes in hexane extracts of the skin were measured during storage. Without warming, scald incidence of the cultivars was 70%, 14%, and 85%, respectively. Intermittent warming treatments resulted in a marked reduction of scald though effectiveness was affected by cultivar. In `Cortland', scald was reduced only by the weekly warming treatment (10%) as was less effective than DPA (1%). In `Delicious', all warming treatments were equally effective. In `Law Rome', weekly warming resulted in better control of scald (3%) than DPA (14%) and less frequent warming was proportionately less effective in controlling the disorder. Concentrations of conjugated trienes at 281 nm did not relate consistently to scald incidence after storage. However, ratios of conjugated trienes of 258 nm or 269 nm with 281 nm strongly support a hypothesis that non-toxic and toxic oxidation products of alpha-farnesene interact and influence the effectiveness of postharvest treatments on scald control (Du and Bramlage, 1993; JASHS 118:807-813). A hypothesis relating the interactions between ripening and scald development will be presented. Supported in part by USDA Specific Cooperative Agreement 58-1931-5-017.

Synthesis of Conjugated Trienes and Related Oxidation Products of α-Farnesene

1994 ◽  
Vol 47 (11) ◽  
pp. 1979 ◽  
Author(s):  
MA Brimble ◽  
DD Rowan ◽  
JA Spicer
Keyword(s):  
Ring Opening ◽  
Room Temperature ◽  
Oxidation Products ◽  
Epoxide Ring ◽  
Epoxide Ring Opening ◽  
Superficial Scald ◽  
Conjugated Trienes ◽  
Conjugated Triene ◽  
Cyclic Peroxide

The synthesis of conjugated trienes and related oxidation products of α- farnesene (1), principally from the epoxides of α- farnesene (1), is reported. Base-promoted ring opening of 6,7-epoxide (4) by KOBut/LiNPri2 affords the conjugated triene (2), whilst the 3,4-epoxide (5) affords trienol (7). In contrast, 10,11-epoxide (6) fails to undergo epoxide ring opening; it rearranges to the conjugated triene epoxide (8). Base-promoted ring opening of bisepoxide (9) afforded trienol epoxide (11) at -30°C, whilst cyclization to tetrahydrofurans (10a,b) occurred at room temperature. Photosensitized oxidation of 10,11-epoxide (6) followed by in situ treatment with acid gave the cyclic peroxide (3) and on reduction triol (12). Bisallylic alcohol (13) was prepared by alkylation of 3-methylsulfolene with geranial. Trienes (2) and (3) have been isolated previously as autoxidation products of α- farnesene (1) and are implicated as the causal agents of superficial scald of stored apples.

scholarly journals CHARACTERISTICS OF UV ABSORBANCE BY HEXANE EXTRACTS OF APPLE SURFACES SUGGEST A MODIFIED HYPOTHESIS ON THE ROLE OF CONJUGATED TRIENES IN SCALD DEVELOPMENT ON APPLES

HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1159d-1159
Author(s):  
Zhanyuan Du ◽  
William J. Bramlage
Keyword(s):  
Hexane Extract ◽  
Uv Absorbance ◽  
Superficial Scald ◽  
Data Support ◽  
Conjugated Trienes ◽  
Hexane Extracts ◽  
Fruit Surface

Much correlative data support the hypothesis that superficial scald on apples results from oxidation of α farnesene to conjugated trienes (CT) in the coating of apples. However, these associations are poorly defined both chemically and physiologically. α Farnesene and CT are measured as OD 232 and OD 281-290, respectively, of a hexane extract of the fruit surface. During assays, we observed anomalies in absorbance characteristics of extracts from fruit with different scald potentials, particularly in the region of 258 nm. Results suggest that absorbance near 258 nm might represent a metabolite of CT, which may be further metabolized. It appeared that under different conditions, CT metabolism could be altered, resulting in changed ratios of OD 258/OD 281. Higher ratios correlated with lower scald development, regardless of CT concentration. Thus, CT metabolism, rather than its concentration, may determine if scald occurs.

scholarly journals Expression of Alpha-farnesene Synthase Gene AFS1 in Relation to Levels of Farnesene and Conjugated Trienols in Peel Tissue of Scald-susceptible `Law Rome' and Scald-resistant `Idared' Apple fruit

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 782B-782
Author(s):  
Steven W. Pechous ◽  
Bruce D. Whitaker* ◽  
Christopher B. Watkins
Keyword(s):  
Sharp Increase ◽  
Biosynthetic Pathway ◽  
Apple Fruit ◽  
Oxidation Products ◽  
High Rate ◽  
Subsequent Increase ◽  
Transcript Levels ◽  
Superficial Scald ◽  
Apple Peel ◽  
Apple Cultivars

Fruit of different apple cultivars vary widely in susceptibility to superficial scald. The genetic and biochemical factors involved in this variation are unknown. Conjugated trienol (CTol) oxidation products of alpha-farnesene have been linked with scald induction, and a high rate of farnesene synthesis in peel tissue of scald-prone apples early in storage is often associated with development of the disorder. Pre-storage treatment of apple fruit with 1-methylcyclopropene (1-MCP) inhibits the early burst of farnesene production and prevents scald, suggesting that ethylene induces transcription of genes involved in farnesene synthesis. We recently cloned a gene from apple peel tissue, AFS1, which encodes alpha-farnesene synthase, the last enzyme in the farnesene biosynthetic pathway. In this study, expression of AFS1 was compared in scaldsusceptible Law Rome (LR) and scald-resistant Idared (IR) apples at harvest and over 20 weeks of storage at 0.5 C. AFS1 transcript levels were closely correlated with accumulation of farnesene and CTols. In fruit of both cultivars, a sharp increase in AFS1 mRNA during the first 4 to 8 weeks of storage preceded a proportional rise in farnesene and a subsequent increase in CTols. However, maximum levels of AFS1 transcript, farnesene, and CTols were, respectively, 2.5-, 4-, and 33-fold greater in LR than in IR apples. Treatment of fruit with 1-MCP at harvest suppressed the increases in AFS1 transcript and farnesene early in storage, but AFS1 expression and farnesene synthesis recovered in LR fruit after 20 weeks. Scald incidence in LR apples after 20 weeks at 0.5 °C plus 1 week at 20 °C averaged 86%, whereas IR fruit had no scald. 1-MCP treatment reduced scald incidence in LR to <1%.

scholarly journals Volatile Cuticular Components Involved in Superficial Scald

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 605a-605
Author(s):  
S. Wee ◽  
R.M. Beaudry
Keyword(s):  
Gas Chromatography ◽  
Mass Spectroscopy ◽  
Malus Domestica ◽  
Apple Fruit ◽  
Superficial Scald ◽  
Conjugated Trienes ◽  
Gas Chromatography Mass Spectroscopy

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.

scholarly journals Biosynthesis of α-Farnesene in Apple Fruit

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 458A-458
Author(s):  
H.P.V. Rupasinghe ◽  
G. Paliyath ◽  
D.P. Murr
Keyword(s):  
Enzyme Purification ◽  
Apple Fruit ◽  
Oxidation Products ◽  
Purification And Characterization ◽  
Developing Regions ◽  
Physiological Disorder ◽  
Superficial Scald ◽  
Feeding Experiments ◽  
Surface Wax

α-Farnesene is an acyclic sesquiterpene hydrocarbon that is a constituent of the surface wax of apples (Malus domestica Borkh.). Although, oxidation products of α-farnesene have been implicated in the development of the physiological disorder superficial scald in apple, the mechanism of α-farnesene biosynthesis has not been studied in detail. We are currently investigating α-farnesene biosynthesis in relation to superficial scald development in apples. Radiolabelled feeding experiments using isolated tissue segments indicated that α-farnesene is derived from trans,trans-farnesyl pyrophosphate (FPP), mainly in the skin rather than cortex. Among the other labeled products detected, farnesol level was over a hundred-fold higher compared to α-farnesene. However, [1-3H] trans,trans-Farnesol was not incorporated into α-farnesene. Feeding radiolabelled FPP to skin tissue segments of scald-developing and normal apples showed differential incorporation of radiolabel into various products. Though the incorporation into α-farnesene was nearly the same, there was higher levels of incorporation into farnesyl esters in normal apples. As well, the levels of radiolabelled in the farnesol fraction was three times higher in scald-developing regions. These results indicate that there are potential difference in the biosynthesis and metabolism of farnesyl components between scald-developing and normal apples. In studies using cell-free extracts, farnesol formation was observed from labeled FPP and was two-fold higher in crude membrane extract compared to crude cytosol. Our results indicate that α-farnesene formation in apple fruit tissue is through FPP and is possibly catalyzed by a single sesquiterpene synthase enzyme. Purification and characterization of this enzyme are in progress.

scholarly journals Farnesene and Trienes in Apple Peel Quantified by HPLC

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 640a-640
Author(s):  
Bruce D. Whitaker ◽  
Theophanes Solomos
Keyword(s):  
Hplc Method ◽  
High Ratio ◽  
Uv Detection ◽  
Oxidation Products ◽  
Superficial Scald ◽  
Absorbance Maximum ◽  
Apple Peel ◽  
Hexane Extracts ◽  
Conjugated Triene ◽  
Low Incidence

Farnesene and its conjugated triene oxidation products in apple peel are positively correlated with, and thought to be involved in, the storage disorder superficial scald. Levels of these compounds are often estimated by dipping fruit in hexane and measuring the absorbance of the crude extracts at 232 nm (farnesene) and 269 or 281 minus 290 nm (trienes). We have devised a C18 HPLC method with UV detection at 232 and 269 nm that allows the simultaneous quantitation of 80 ng of farnesene and trienes. Using this method we have confirmed the recent report that one conjugated trien-6-ol comprises 90% of the stable oxidation products of farnesene. It was also found that crude hexane extracts of apple peel can give spuriously high values for farnesene and/or trienes when levels of these compounds are low and other UV-absorbing components are present. A group of compounds unrelated to farnesene, with an absorbance maximum at ≈259 nm, were noted in the peel of cv. Gala apples, which produced little farnesene or trienol. This may explain the report that fruit with a high ratio of A258nm/A281nm in peel extracts have a low incidence of scald. The new HPLC method will be applied in subsequent studies of postharvest factors involved in regulation of farnesene synthesis and oxidation.

scholarly journals Does Enhanced Removal of Active Oxygen Species Contribute Resistance to Superficial Scald in Apple Fruits?

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 535D-535
Author(s):  
Rao V. Mulpuri ◽  
Chris B. Watkins
Keyword(s):  
Antioxidant Enzymes ◽  
Carbonyl Compounds ◽  
Active Oxygen Species ◽  
Apple Fruit ◽  
Superficial Scald ◽  
Degrading Enzymes ◽  
Conjugated Trienes ◽  
Molecular Aspects ◽  
Susceptible Populations ◽  
Apple Fruits

Apple fruits are highly susceptible to superficial scald, which is currently controlled by both chemical- and non-chemical-based technologies. The possible threat of withdrawal of diphenylamine (DPA) for the control of superficial scald has prompted us to investigate the biochemical and molecular aspects of scald resistance. We have selected genetic populations of a cross between `White Angel' and `Rome Beauty' that are resistant and susceptible to scald, and investigated whether the resistance of scald in these populations is due to the higher antioxidant-based defense systems. Cortical tissue of fruits (0–3 cm) was peeled and analyzed for conjugated trienes, H2O2, carbonyl groups, and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidases (POX). Scald-resistant fruits at harvest had higher antioxidant enzymes and low levels of conjugated trienes, carbonyl compounds, and H2O2 levels compared to fruits that are susceptible to scald. Further, H2O2 levels rose in scald-susceptible fruits stored under low temperature with a concomitant increase in the production of conjugated trienes and carbonyl compounds, while no major changes were observed in scald-resistant fruits. Enhanced levels of H2O2 in scald-susceptible populations could be related to enhanced SOD activities and decreased activities of H2O2 degrading enzymes, suggesting that an imbalance between \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{O}_{2}^{-}{/}\mathrm{H}_{2}\mathrm{O}_{2}\) \end{document} may have occurred. These results indicate that a coordination between SOD and H2O2 degrading enzymes in scald resistant populations may have minimized the influence of AOS on the oxidation of α-farnesene, protein, and, thereby, on scald. Hence, we have hypothesized that enhancing the potential of apple fruit to metabolize AOS develops resistance to superficial scald. [Supported in part by USDA Specific Cooperative Agreement 58-1931-5-017.]

scholarly journals (29) MCP Treatment Makes Delayed Application of Ethoxyquin Effective in Control of Superficial Scald of `d'Anjou' Pears

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1004A-1004
Author(s):  
Jinhe Bai
Keyword(s):  
Ethylene Production ◽  
Room Temperature ◽  
Oxidation Products ◽  
Mass Treatment ◽  
Fruit Peel ◽  
Superficial Scald ◽  
Conjugated Trienes

Superficial scald of `d'Anjou' pears usually develops after storage of 2 months or longer. MCP application controls scald; however, fruit lose their ripening capacity if the dosage is >30 ppb, but lower dosages cannot control scald substantially. In this study, fruit treated with or without 25 ppb MCP within 2 d after harvest were stored at –1 °C for up to 5 months. After 1, 7, 30, or 70 d of storage, part of the fruit were pulled from storage and treated with 1000 ppm ethoxyquin line spray and immediately returned to the storage, left untreated as non-ethoxyquin control. Incidence of superficial scald along with the concentrations of α-farnesene and conjugated trienes (CTs), and the ripening capacity of fruit were investigated after 3, 4, and 5 months storage. All fruit ripened properly within 7 d of conditioning at room temperature regardless of treatments. Both of MCP or ethoxyquin-1d (ethoxyquin was applied after 1 day storage at –1 °C) alone controlled scald for only 3 months; however, MCP + ethoxyquin controlled scald for 5 months, whenever ethoxyquin was applied between 1 to 70 d after storage. Thus, with 25 ppb MCP treatment, which is simple, with rapid and mass treatment available, a delayed application (up to 70 d) of ethoxyquin becomes effective to control scald. Furthermore, the later application of ethoxyquin within 70 d after MCP treatment, the less incidence of scald was observed. Scald is caused by the CTs oxidation products of α-farnesene. MCP and ethoxyquin inhibited accumulation of CTs of fruit peel by different mechanisms. MCP inhibited the production by influencing ethylene production through control of α-farnesene synthesis; however, ethoxyquin worked by inhibiting the oxidation of α-farnesene to the CTs.

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