scholarly journals Rethinking Apple Scald: New Hypothesis on the Causal Reason for Development of Scald in Apples

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 605c-605 ◽  
Author(s):  
J. Song ◽  
R.M. Beaudry
Keyword(s):  
Apple Fruit ◽  
Cuticular Wax ◽  
Dynamic Changes ◽  
Toxic Compounds ◽  
Superficial Scald ◽  
Resistant Cultivars ◽  
Physiological Disorders ◽  
Close Relationship ◽  
New Hypothesis

Superficial scald is still one of the most important postharvest physiological disorders in apples. Commercial control of this disorder has been accomplished by selecting resistant cultivars, treating fruit with DPA and ethoxyquin, using oil-soaked fruit wraps and storing the fruit under low O2. However, the causal reason for scald development is still a mystery. Research has indicated that the scald-promoting factor or inducing compound may be formed or accumulated in apple cuticle then rediffused back into the hypodermis, thereby causing damage. Hydroperoxides, auto-oxidative product from α-farnesene, have been thought to be the toxic compounds, inducing scald; however, it is not explained how the hydroperoxides move from the cuticle to the hypodermis. The identification and dynamic changes of 6-methyl-5-heptene-2-one as a natural volatile in apple fruit during ripening were made, which accumulated in higher quantitaty in cuticular wax than in headspace. The close relationship between the chloroplast breakdown and amount of α-farnesene changes, the induction of scald-like symptom on the surface of apple fruit by 6-methyl-5-heptene-2-one and the sensitivity of fruit to this ketone damage were investigated. Our results suggest that the accumulation of 6-methyl-5-heptene-2-one in the cuticular wax of apple fruit might be the causal reason for scald development in apples.

scholarly journals Ethylene –dependent and –independent superficial scald resistance mechanisms in ‘Granny Smith’ apple fruit

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Evangelos Karagiannis ◽  
Michail Michailidis ◽  
Georgia Tanou ◽  
Martina Samiotaki ◽  
Katerina Karamanoli ◽  
...  
Keyword(s):  
Resistance Mechanisms ◽  
Apple Fruit ◽  
Superficial Scald

Comparative analysis of the total and active bacterial communities in the surface sediment of Lake Taihu

2020 ◽  
Vol 96 (5) ◽  
Author(s):  
Tong-tong Liu ◽  
Hong Yang
Keyword(s):  
Bacterial Community ◽  
Surface Sediment ◽  
Bacterial Communities ◽  
Surface Sediments ◽  
Lake Taihu ◽  
Dynamic Changes ◽  
Dna And Rna ◽  
Close Relationship ◽  
Total Bacterial Community ◽  
Quantitative Results

ABSTRACT Bacterial communities play crucial roles in the biogeochemical cycle of the surface sediments of freshwater lakes, but previous studies on bacterial community changes in this habitat have mostly been based on the total bacterial community (DNA level), while an exploration of the active microbiota at the RNA level has been lacking. Herein, we analysed the bacterial communities in the surface sediments of Lake Taihu at the DNA and RNA levels. Using MiSeq sequencing and real-time quantification, we found that the sequencing and quantitative results obtained at the RNA level compared with the DNA level were more accurate in responding to the spatiotemporal dynamic changes of the bacterial community. Although both sequencing methods indicated that Proteobacteria, Chloroflexi, Acidobacteria, Nitrospirae, Bacteroidetes and Actinobacteria were the dominant phyla, the co-occurrence network at the RNA level could better reflect the close relationship between microorganisms in the surface sediment. Additionally, further analysis showed that Prochlorococcus and Microcystis were the most relevant and dominant genera of Cyanobacteria in the total and active bacterial communities, respectively; our results also demonstrated that the analysis of Cyanobacteria-related groups at the RNA level was more ‘informative’.

Timing of a cellular reaction in rice cultivars associated with differing degrees of resistance to Pyricularia oryzae

1989 ◽  
Vol 67 (9) ◽  
pp. 2704-2710 ◽  
Author(s):  
You-Liang Peng ◽  
Jiko Shishiyama
Keyword(s):  
Growth Inhibition ◽  
Cell Walls ◽  
Leaf Age ◽  
Blue Staining ◽  
Resistant Cultivars ◽  
Close Relationship ◽  
Time Required ◽  
Moderately Resistant ◽  
The Relationship ◽  
Aniline Blue Staining

To clarify the relationship between histological events and lesion formation in incompatible rice and rice blast fungus interaction, penetration frequency, growth of infection hyphae, and cellular reactions were compared in 12 cultivars, each of which showed one of the following four resistant reactions: highly resistant, resistant, moderately resistant, or intermediate. Penetration frequency varied depending on the cultivar, leaf age, and fungal isolate. Papilla-like structures were observed at some unsuccessful penetration sites, but their formation was too restricted to be responsible for the penetration failure of most conidia. Growth of infection hyphae stopped before 24 h in highly resistant cultivars, before 36 h in resistant cultivars, and later than 36 h in moderately resistant cultivars. The growth inhibition of infection hyphae was coincident with the occurrence of a light brown coloration and aniline blue staining of cell walls (B reactions) around infection sites in these cultivars. These results indicate a close relationship between occurrence of B reactions and growth inhibition of infection hyphae and suggest that the time required for B reactions to occur and for growth infection hyphae to stop varies according to degree of host resistance.

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.

scholarly journals Aroma Volatile Production in Preharvest AVG-treated `Golden Delicious' Apple Fruit and the Effect of Poststorage Ethylene Treatment

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 781E-782
Author(s):  
Jun Song ◽  
Fritz Bangerth
Keyword(s):  
Ethylene Biosynthesis ◽  
Apple Fruit ◽  
Straight Chain ◽  
Ethylene Treatment ◽  
Close Relationship ◽  
Aroma Production ◽  
Branched Chain ◽  
The Relationship ◽  
Volatile Production ◽  
Apple Fruits

Changes in the profile of aroma volatiles during ripening and after ethylene treatment in apple fruit have revealed a close relationship exists between ethylene production and the timing and magnitude of volatile synthesis. Therefore, AVG (ethylene biosynthesis inhibitor) was used to study the relationship between volatile biosynthesis and metabolic processes affected by ethylene in apple fruits. AVG-treated fruit were stored either for 1 month at 2C in air or 5 months in ULO condition. During the post-storage ripening, the fruits were exposed to 50 μl·liter–1 of ethylene at least 12 h/day. Aroma production was determined at 20C. Total volatile compound production by AVG-treated fruit was much lower than that of untreated fruit. A significant increase in the production of most aroma volatile after 1 month storage in air was induced by ethylene treatment to AVG-treated fruits. I was noted that branched-chain volatile, such as 2-methylbutylacetate, which originates from branched-chain amino acids, has increased prior to butylacetate and hexylacetate, which are derived from fatty acids. Ethylene treatment was unable to stimulate the production of straight-chain volatile compounds following the 5 months of ULO storage. These results are consistent with observations suggesting apple fruit lose their sensitivity to ethylene after long ULO storage.

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 An apple long-chain acyl-CoA synthetase 2 gene enhances plant resistance to abiotic stress by regulating the accumulation of cuticular wax

2020 ◽  
Vol 40 (10) ◽  
pp. 1450-1465 ◽  
Author(s):  
Chun-Ling Zhang ◽  
Xing Hu ◽  
Ya-Li Zhang ◽  
Yang Liu ◽  
Gui-Luan Wang ◽  
...  
Keyword(s):  
Fruit Quality ◽  
Molecular Mechanisms ◽  
Soil Salinization ◽  
Apple Fruit ◽  
Cuticular Wax ◽  
Synthetase Activity ◽  
Fruit Storage ◽  
Chain Acyl ◽  
Adverse Environmental Conditions ◽  
Long Chain

Abstract Apple cuticular wax can protect plants from environmental stress, determine fruit luster and improve postharvest fruit storage quality. In recent years, dry weather, soil salinization and adverse environmental conditions have led to declines in apple fruit quality. However, few studies have reported the molecular mechanisms of apple cuticular wax biosynthesis. In this study, we identified a long-chain acyl-CoA synthetase MdLACS2 gene from apple. The MdLACS2 protein contained an AMP-binding domain and demonstrated long-chain acyl-CoA synthetase activity. MdLACS2 transgenic Arabidopsis exhibited reductions in epidermal permeability and water loss; change in the expression of genes related to cuticular wax biosynthesis, transport and transcriptional regulation; and differences in the composition and ultrastructure of cuticular wax. Moreover, the accumulation of cuticular wax enhanced the resistance of MdLACS2 transgenic plants to drought and salt stress. The main protein functional interaction networks of LACS2 were predicted, revealing a preliminary molecular regulation pathway for MdLACS2-mediated wax biosynthesis in apple. Our study provides candidate genes for breeding apple varieties and rootstocks with better fruit quality and higher stress resistance.

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