Letteratura scientifica selezionata sul tema "Chilling injury (CI)"

`Gemini II' cucumber (Cucumis sativus L.) fruits were stored for 2, 4, or 6 days at 5 and 6C in 1989 and for 5 days at SC or 10 days at 3C in 1990. Chilling injury (CI) symptoms were rated after 2 to 4 days at 25C. Cell wall polysaccharide concentrations in the peels and in injured and noninjured portions of the peels were determined only in 1990. High CO2 and low O2 delayed the onset of CI symptoms, but did not prevent symptom development. Chilling injury symptoms increased with longer exposure to chilling temperatures. Solubilization of cell wall polysaccharides was associated with development of CI symptoms. Variations in low methoxyl pectinates accounted for 70% of the variation in CI.

Release, localization, and concentration of essential oils in chilling-injured and noninjured lemon [Citrus limon (L.) Burm.] fruit were investigated to enhance understanding of how chilling injury (CI) occurs in lemon. CI in the form of moderate to severe pitting of the flavedo was initially apparent after 3 weeks at 1 °C, followed by a gradual increase in severity until termination of the experiment after 7 weeks at 1 °C. Curing the fruit at 15 °C for 1 week before cold treatment greatly reduced the severity of CI. Release from the fruit of d-limonene, a major component of essential oil in lemon, increased with increasing amounts of CI. The enhancement of d-limonene release, however, lagged behind the development of CI. Studies of the internal anatomy of the flavedo using confocal microscopy indicated that essential oils were abundantly present inside the oil gland and in oil bodies outside the gland. Chilling-injured flavedo exhibited no obvious disruption of either the oil glands or the oil bodies. Extraction and quantification of d-limonene from chilling-injured and noninjured flavedo indicated that similar amounts of oil were present in the tissue, regardless of injury. Damage to the flavedo after 3 weeks at 1 °C was noted in the form of flattened or collapsed cells between the top of the gland and the epidermis, whereas collapse of the oil gland only was observed in later stages of injury development.

Abstract Symptoms of chilling injury (Cl) expressed as internal browning (IB) in fresh pineapple [Ananas comosus (L.) Merr.] began to appear within 2 days at 22°C after a period of storage at temperatures less than 12°. Fruit not subjected to chilling temperatures during storage also developed similiar symptoms when held for 0 to 10 days at between 18° and 30°. Fruit stored for longer than 3 weeks at temperatures of 8° and 3° showed fewer CI symptoms than similar fruit held at 12°. Waxing fruit either before or immediately after exposure to chilling temperatures was equally effective in reducing CI symptoms. Low oxygen (3%), with or without (5%) carbon dioxide during chilling did not reduce symptom expression. Storage of fruit under low oxygen following chilling significantly reduced CI symptom expression. A model for CI symptom development is presented and related to the metabolic events leading to IB of pineapple fruit, stored at chilling temperatures.

Abstract Susceptibility to chilling injury in ‘Kapoho’ papayas (Carica papaya L.) was reduced by ripening the fruit before storage at 5°C. The relationship between the decrease in chilling injury (CI) and postharvest ripening time at 24° was found to follow first order kinetics, hence, the half-lives for reducing the symptoms of CI of scald and hard core are 14.8 and 33.5 hr, respectively.

Five tomato cultivars were tested for tolerance to chilling. After exposure of varying times to chilling at 3 °C, the fruits were returned to ambient temperature for development of chilling injury (CI) symptoms (uneven ripening and pitting). Ripening was assessed by measuring carotenoids. Electrical conductivity (EC) of leachate from pericarp discs, an indirect measure of membrane damage, was used to determine CI. During chilling EC greatly increased in the three sensitive cultivars, but hardly in the tolerant ones, in good correlation with the development of CI symptoms after rewarming. However, this correlation broke down after returning the fruit to 20 °C. While slightly injured fruit showed a large increase in EC, surprisingly EC was drastically reduced in the extensively injured fruit. Calcium pectate production due to cell wall degradation may explain the lack of correlation between EC and CI after rewarming. We conclude that EC is not always a reliable measure of membrane damage.

In previous studies squalene was shown to be synthesized in grapefruit under temperature-conditioning parameters optimal for preventing chilling injury (CI). In this study, squalene and its saturated derivative squalane were applied to the fruit as sprays or dips under various protocols. Fruit were stored for various times under conditions conducive to CI. The best results were obtained when fruit were sprayed with squalene dissolved in hexane. After 4 weeks at 5C, 5% squalene reduced CI 69% and 10% squalene reduced CI 80% whereas, temperature conditioning reduced CI by a comparable amount (67%).

Storage of `Marsh' white seedless grapefruit (Citrus paradisi Macf.) for 2 weeks at 5C resulted in the development of chilling injury (CI). Electrolyte leakage from chilled fruit did not increase significantly until CI had become severe, and was therefore considered to be a poor index of CI. In contrast to electrolyte leakage, respiration and ethylene evolution were consistently higher in chilled than in nonchilled fruit, even prior to the onset of visual symptoms of CI. Respiratory rates ranged from 8.0 to 10.7 and 4.6 to 6.7 ml/kg/hr in chilled and nonchilled fruit, respectively. Ethylene evolution was not detected from nonchilled fruit, whereas chilled fruit produced from 45.6 to 249.3 ml/kg/hr ethylene. Ethylene production was maximum following 2 weeks at 5C. Results of this study indicate that increases in electrolyte leakage do not occur until considerable tissue damage has occurred, whereas stimulation of respiration and ethylene evolution occur early in the development of CI.

The storage of persimmon cv. Rojo Brillante (Diospyros kaki L.) at low temperatures is limited by the susceptibility to chilling injury (CI), the main symptom being a drastic reduction of firmness when the fruit are transferred from low to moderate temperature. 1-Methylcyclopropene (1-MCP), an ethylene action inhibitor, has been shown to alleviate CI of persimmon, prolonging the storage period. In this article, the microstructural changes produced in the flesh of chilling-injured persimmon and fruit treated with 1-MCP were studied. The drastic softening displayed by chilling-injured fruit was related to a loss of cell wall integrity as well as to low intercellular adhesion. 1-MCP treatment alleviated CI by preserving the fruit firmness; it was linked to a preservation of the cell wall's integrity and to a higher intercellular adhesion observed during storage at low temperatures as well as when fruit were transferred to shelf temperatures.

Green-ripe banana fruit are sensitive to chilling injury (CI) and, thus, prone to postharvest quality losses. Early detection of CI facilitates quality maintenance and extends shelf life. CI affects all metabolic levels, with membranes and, consequently, photosynthesis being primary targets. Optical techniques such as chlorophyll a fluorescence analysis (CFA) and spectroscopy are promising tools to evaluate CI effects in photosynthetically active produce. Results obtained on bananas are, however, largely equivocal. This results from the lack of a rigorous evaluation of chilling impacts on the various aspects of photosynthesis. Continuous and modulated CFA and imaging (CFI), and VIS remission spectroscopy (VRS) were concomitantly applied to noninvasively and comprehensively monitor photosynthetically relevant effects of low temperatures (5 °C, 10 °C, 11.5 °C and 13 °C). Detailed analyses of chilling-related variations in photosynthetic activity and photoprotection, and in contents of relevant pigments in green-ripe bananas, helped to better understand the physiological changes occurring during CI, highlighting that distinct CFA and VRS parameters comprehensively reflect various effects of chilling on fruit photosynthesis. They revealed why not all CFA parameters can be applied meaningfully for early detection of chilling effects. This study provides relevant requisites for improving CI monitoring and prediction.

Chilling injury (CI) is an important postharvest physiological problem that limits the storage life of many warm-season fruits and vegetables. Variability exists among cultivars and CI appears to be related to moisture loss during low temperature storage. The relationship between moisture loss and CI was examined using fruit from 64 PI lines of field-grown Cucumis sativus. A wide variation existed among the lines in the sensitivity of their fruit to low temperatures. Fruit from 8 of the lines developed severe symptoms of CI after 5 days at 5°C and fruit from 21 lines developed no injury symptoms. CI symptoms developing during 2 and 4 days of storage at 15°C were highly significantly correlated with weight loss during the 5 days of storage at 5°C. Crosses were made between chilling-sensitive and chilling-resistant lines. CI symptoms of the F1 fruit were highly significantly correlated with weight loss during the 5 days of storage at 5°C.

The primary objective of the research was to study the physiological and biochemical changes in Hass avocado fruit stored in different combination of oxygen and carbon dioxide concentrations at both 0 degrees and 5 degrees Centigrade (C), and to determine whether storage in controlled atmosphere (CA) can decrease the incidence of chilling injury (CI). A secondary objective was to identify possible correlations between CA, the incidence of CI, the activity of some ripening related enzymes and changes in proteins during ripening at 20 degrees C following storage at low temperatures. Fruit suffered no CI and ripened normally following CA storage for 3 weeks at both 0 degrees and 5 degrees C, then transferred to air for 6 days at 20 degrees C. CI symptoms did develop after CA storage for 6 and 9 weeks at 0 degrees C. Changes in proteins during ripening were analysed by 2D-PAGE. Some polypeptides were detected in unripe fruit but decreased with ripening. Polypeptides of 16.5, 25, 36 and 56 kD (kilo Dalton) were present early in ripening and their levels further increased during ripening. The appearance of three ripening related polypeptides with estimated molecular weights 80 kD (pI 3.6), 36 kD (pI 5.8) and 16.5 kD (pI 5.7) was observed in fruit at the climacteric stage. Three polypeptides with estimated molecular weights of 41 kD (pI7.8), 36 kD (pI 5.8) and 33 kD (pI 5.1) were found in air stored fruit but were not detected in fruit stored in CA. This research showed that CA did not ameliorate CI at 0 degrees C, instead storage at 0 degrees C caused a premature increase in ethylene production when the fruit were returned to air at 20 degrees C. In contrast, CA storage at 5 degrees C retarded ethylene production and ripening in fruit after it was returned to air at 20 degrees C.
Doctor of Philosophy (PhD)

Postharvest life and susceptibility to chilling injury (CI) in Japanese plums (Prunus salicina Lindl.) are greatly influenced by preharvest and postharvest factors. The phenomenon of postharvest oxidative stress has been implicated in affecting fruit quality, potential storability and susceptibility to development of physiological disorders during storage of fruits. Therefore, the investigations were carried out to understand the role of various factors, such as cultivar, harvest maturity, storage conditions (temperature and atmosphere composition), duration of storage and postharvest treatments, in the development of oxidative stress in Japanese plums, in relation to fruit quality and CI. The degree of lipid peroxidation and membrane integrity was measured by determining the activity of lipoxygenase enzyme, concentration of thiobarbituric acid–reactive substances, and amount of electrolyte leakage. The activities of antioxidant enzymes, superoxide dismutase, catalase, and peroxidase, were determined as a direct measure of the enzymatic antioxidant capacity. The activities of enzymes (ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and glutathione–S–transferase) involved in the oxidation and regeneration of ascorbate (AA) and glutathione (GSH) were also determined to underpin the dynamics of the AA–GSH cycle. The concentrations of AA, dehydroascorbate (DHA), GSH, and oxidized glutathione (GSSG) were determined to compute the AA:DHA and GSH:GSSG ratios as the indicators of redox potential of fruit tissue. The total phenolics concentration and total antioxidant capacity were also determined as a part of the non–enzymatic antioxidants.The experimental data suggest that postharvest oxidative stress developed during fruit ripening in Japanese plums, but the rate was dependent on the climacteric behaviour of fruit. The climacteric cultivars, ‘Blackamber’ and ‘Amber Jewel’, showed a faster decline in the ability of antioxidative system to encounter the oxidative stress during fruit ripening as compared to ‘Angeleno’, a suppressed–climacteric cultivar. The delay in harvesting of ‘Amber Jewel’ plums by one week slightly improved fruit quality and the initial status of antioxidants than the commercial harvest. However, the fruit harvested at commercial maturity had better retention of antioxidative system during cold storage at 0°C for 3–4 weeks compared to the fruit from the delayed harvest. The changes in enzymatic and non–enzymatic antioxidants as a function of storage duration appear to be more prominent in providing protection against oxidative injury expressed as CI than their at–harvest status. The response of the antioxidative system in ‘Amber Jewel’ plums at 5°C was significantly better than at 0°C. But, the storage temperature of 5°C was not sufficiently low to inhibit the process of fruit ripening, resulting in limited storage life of 2 weeks. The multiple–point time course analysis of lipid peroxidation and changes in enzymatic and non–enzymatic antioxidants of ‘Blackamber’ plums revealed that the third week of storage is the critical point beyond which the capacity of antioxidative system to cope with the increasing oxidative stress from CI and fruit ripening began to decline, resulting in increased incidence and severity of CI during the extended periods of storage. Controlled atmospheres (CA) were found beneficial to reduce the levels of oxidative stress in ‘Blackamber’ plums.CA containing 1% O[subscript]2 + 3% CO[subscript]2 were effective in mitigating the oxidative stress during the 5 weeks of cold storage at 0–1°C, plus 6 days of shelf life at 21±1°C. The efficacy of CA (1% or 2.5% O[subscript]2 + 3% CO[subscript]2) in alleviating CI in ‘Blackamber’ plums could be further enhanced by the pre–storage treatment of fruit with 1–methylcyclopropene (1–MCP, 0.6 μL L[superscript]–[superscript]1). The combination of CA and 1–MCP exhibited synergistic effects on the alleviation of oxidative stress, resulting in enhanced storage life up to 8 weeks, plus 6 days of shelf–life. The role of nitric oxide (NO) as an antioxidant was also investigated in order to retard fruit ripening, delay the onset of senescence and development of oxidative stress in the Japanese plums. Postharvest NO fumigation (10 or 20 μL L[superscript]–[superscript]1) delayed the fruit ripening and maintained quality for 9–12 days in ‘Amber Jewel’ and ‘Blackamber’ plums at 21±1°C. NO fumigation was also beneficial to reduce the symptoms of CI during cold storage of ‘Amber Jewel’ and ‘Blackamber’ plums for 5–6 weeks at 0°C, plus 5 days of shelf–life at 21±1°C. The positive effects of NO fumigation on the enzymatic and non–enzymatic antioxidants in addition to reduced rates of lipid peroxidation were associated with the enhanced chilling tolerance in Japanese plums. The response of ‘Amber Jewel’ to postharvest NO fumigation was significantly better than ‘Blackamber’.In conclusion, the development of oxidative stress in Japanese plums was influenced by cultivar, harvest maturity, cold storage (temperature, duration and atmosphere composition), and postharvest treatments with NO and 1–MCP. The mitigation of oxidative stress by manipulation of postharvest storage conditions and treatments can be achieved to maintain fruit quality and reduce the incidence and severity of CI in Japanese plums.

ABSTRACT Postharvest losses of fresh produce are estimated globally to be around 30%. Reducing these losses is considered a major solution to ensure global food security. Storage at low temperatures is an efficient practice to prolong postharvest performance of crops with minimal negative impact on produce quality or human health and the environment. However, many fresh produce commodities are susceptible to chilling temperatures, and the application of cold storage is limited as it would cause physiological chilling injury (CI) leading to reduced produce quality. Further, the primary CI becomes a preferred site for pathogens leading to decay and massive produce losses. Thus, chilling sensitive crops should be stored at higher minimal temperatures, which curtails their marketing life and in some cases necessitates the use of other storage strategies. Development of new knowledge about the biological basis for chilling tolerance in fruits and vegetables should allow development of both new varieties more tolerant to cold, and more efficient postharvest storage treatments and storage conditions. In order to improve the agricultural performance of modern crop varieties, including tomato, there is great potential in introgression of marker-defined genomic regions from wild species onto the background of elite breeding lines. To exploit this potential for improving tomato fruit chilling tolerance during postharvest storage, we have used in this research a recombinant inbred line (RIL) population derived from a cross between the red-fruited tomato wild species SolanumpimpinellifoliumL. accession LA2093 and an advanced Solanum lycopersicumL. tomato breeding line NCEBR-1, developed in the laboratory of the US co-PI. The original specific objectives were: 1) Screening of RIL population resulting from the cross NCEBR1 X LA2093 for fruit chilling response during postharvest storage and estimation of its heritability; 2) Perform a transcriptopmic and bioinformatics analysis for the two parental lines following exposure to chilling storage. During the course of the project, we learned that we could measure greater differences in chilling responses among specific RILs compared to that observed between the two parental lines, and thus we decided not to perform transcriptomic analysis and instead invest our efforts more on characterization of the RILs. Performing the transcriptomic analysis for several RILs, which significantly differ in their chilling tolerance/sensitivity, at a later stage could result with more significant insights. The RIL population, (172 lines), was used in field experiment in which fruits were examined for chilling sensitivity by determining CI severity. Following the field experiments, including 4 harvest days and CI measurements, two extreme tails of the response distribution, each consisting of 11 RILs exhibiting either high sensitivity or tolerance to chilling stress, were identified and were further examined for chilling response in greenhouse experiments. Across the RILs, we found significant (P < 0.01) correlation between field and greenhouse grown plants in fruit CI. Two groups of 5 RILs, whose fruits exhibited reproducible chilling tolerant/sensitive phenotypes in both field and greenhouse experiments, were selected for further analyses. Numerous genetic, physiological, biochemical and molecular variations were investigated in response to postharvest chilling stress in the selected RILs. We confirmed the differential response of the parental lines of the RIL population to chilling stress, and examined the extent of variation in the RIL population in response to chilling treatment. We determined parameters which would be useful for further characterization of chilling response in the RIL population. These included chlorophyll fluorescence Fv/Fm, water loss, total non-enzymatic potential of antioxidant activity, ascorbate and proline content, and expression of LeCBF1 gene, known to be associated with cold acclimation. These parameters could be used in continuation studies for the identification and genetic mapping of loci contributing to chilling tolerance in this population, and identifying genetic markers associated with chilling tolerance in tomato. Once genetic markers associated with chilling tolerance are identified, the trait could be transferred to different genetic background via marker-assisted selection (MAS) and breeding. The collaborative research established in this program has resulted in new information and insights in this area of research and the collaboration will be continued to obtain further insights into the genetic, molecular biology and physiology of postharvest chilling tolerance in tomato fruit. The US Co-PI, developed the RIL population that was used for screening and measurement of the relevant chilling stress responses and conducted statistical analyses of the data. Because we were not able to grow the RIL population under field conditions in two successive generations, we could not estimate heritability of response to chilling temperatures. However, we plan to continue the research, grow the RIL progeny in the field again, and determine heritability of chilling tolerance in a near future. The IS and US investigators interacted regularly and plan to continue and expand on this study, since combing the expertise of the Co-PI in genetics and breeding with that of the PI in postharvest physiology and molecular biology will have great impact on this line of research, given the significant findings of this one-year feasibility project.

The use of pretreatments for 24 h prior to storage, under anaerobic condtions, or in the presence of the natural metabolic products, acetaldehyde (AA) and ethanol, to delay fruit ripening, was found to be effective with several climacteric fruits, among them avocado, mango, peach and tomato. The delay in ripening of avocado, peach and tomato was accompanied by inhibition of ethylene production and of fruit softening. The maintenance of fruit firmness was associated with a decrease in the activities of cell-wall-degrading enzymes, including endoglucanases (Cx), polygalacturonases (PG) and b-galactosidases. In peaches the AA- and N2-treated fruits were firmer after 3 weeks storage and contained higher amount of insoluble pectin than untreated controls. We showed that AA vapors are able to inhibit ripening, ethylene production and ethylene induction in the presence of 1-amino-cyclopropane-1-carboxylic acid (ADD) in avocado and mango tissue. Ethylene induced by ACC is taken as an indicator of ACC oxidase activity. ACC oxidase activity in AA-treated avocado fruit was much lower than in the untreated fruit. In carnation flowers very little ethylene was produced by ethanol-treated flowers, and the normal increases in ACC content and ACC oxidase activity were also suppressed. Using kinetic studies and inhibitors of alcohol dehydrogenase (ADH), we showed that AA, not ethanol, was the active molecule in inhibiting ripening of tomato fruit. Application of anaerobiosis or anaerobic metabolites was effective in reduction of chilling injury (CI) in various plant tissues. Pretreatment with a low-O2 atmosphere reduced CI symptoms in avocado; this effect was associated with higher content of the free sylfhydryl (SH) group, and induction of the detoxification enzymes, catalase and peroxidase. Application of AA maintained firmer and brighter pulp tissue (non-oxidative), which was associated with higher free SH content, lower ethylene and ACC oxidase activities, and higher activities of catalase and peroxidase. Ethanol was found to reduce CI in other plant tissue. In roots of 24-h-old germinated cucumber seeds, exposure to 0.4-M ethanol shock for 4 h reduced chilling-induced ion leakage. In cucumber cotyledons it appears that alcohols may reduce CI by inducing stomata closure. In cotyledon discs held in N2 at 10C for 1 day, there accumulated sufficient endogenously synthesized ethanol to confer tolerance to chilling at 2.5C for 5 days.

Peach and nectarine production worldwide is increasing; however consumption is flat or declining because of the inconsistent eating quality experienced by consumers. The main factor for this inconsistent quality is mealiness or woolliness, a form of chilling injury that develops following shipping periods in the global fruit market today. Our research groups have devised various postharvest methods to prolong storage life, including controlled atmosphere and delayed storage; however, these treatments only delay mealiness. Mealiness texture results from disruption of the normal ripening process involving disassembly of cell wall material, and creates a soft fruit texture that is dry and grainy instead of juicy and smooth. Solving this problem is a prerequisite for increasing the demand for fresh peach and nectarine. Two approaches were used to reveal genes and their associated biochemical processes that can confer resistance to mealiness or wooliness. At the Volcani Center, Israel, a nectarine cultivar and the peach cultivar (isogenetic materials) from which the nectarine cultivar spontaneously arose, and at the Kearney Agricultural Center of UC Davis, USA, a peach population that segregates for quantitative resistance to mealiness was used for dissecting the genetic components of mealiness development. During our project we have conducted research integrating the information from phenotypic, biochemical and gene expression studies, proposed possible candidate genes and SNPs-QTLs mapping that are involved in reducing peach mealiness susceptibility. Numerous genes related to ethylene biosynthesis and its signal transduction, cell wall structure and metabolism, stress response, different transcription factor families were detected as being differentially accumulated in the cold-treated samples of these sensitive and less sensitive genotypes. The ability to produce ethylene and keep active genes involved in ethylene signaling, GTP-binding protein, EIN-3 binding protein and an ethylene receptor and activation of ethyleneresponsive fruit ripening genes during cold storage provided greater resistance to CI. Interestingly, in the functional category of genes differentially expressed at harvest, less chilling sensitive cultivar had more genes in categories related to antioxidant and heat sock proteins/chaperones that may help fruit to adapt to low temperature stress. The specific objectives of the proposed research were to: characterize the phenotypes and cell wall components of the two resistant systems in response to mealiness- inducing conditions; identify commonalities and specific differences in cell wall proteins and the transcriptome that are associated with low mealiness incidence; integrate the information from phenotypic, biochemical, and gene expression studies to identify candidate genes that are involved in reducing mealiness susceptibility; locate these genes in the Prunus genome; and associate the genes with genomic regions conferring quantitative genetic variation for mealiness resistance. By doing this we will locate genetic markers for mealiness development, essential tools for selection of mealiness resistant peach lines with improved fruit storability and quality. In our research, QTLs have been located in our peach SNPs map, and proposed candidate genes obtained from the integrated result of phenotypic, biochemical and gene expression analysis are being identified in our QTLs as an approach searching for consistent assistant markers for peach breeding programs.