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Heat treatment is widely used as a postharvest strategy to extend the shelf life of fleshy fruits. Nevertheless, understanding the mechanisms by which heat stress exerts its effect continues to be a topic of interest. We studied the influence of heat treatment (3 h in an air oven at 45 ± 1 °C) on the modulation of defence mechanisms in ripe strawbe...
The purpose of the present work was to provide novel knowledge about the mechanisms underlying the preservation of strawberry fruit by 1-methylcyclopropene (1-MCP) treatment during storage. Harvest-ripe strawberries were treated with 1-MCP for ten hours at 22 °C and then stored for ten days at 4 °C and two days at 20 °C. 1-MCP treatment significant...
Broccoli contains a high content of nutraceutical compounds, such as glucosinolates and flavonoids. In this work, the effect of different treatments that modulate postharvest senescence of broccoli was evaluated and flavonoid metabolism during postharvest storage was analyzed at 20°C. A decrease in hue angle (HUE°) and chlorophylls and an increase...
BACKGROUND
Softening is one of the main features that determine fruit quality during strawberry (Fragaria x ananassa, Duch.) ripening and storage. Being closely related to textural changes, the molecular and biochemical bases underlying strawberry cell‐wall metabolism is a matter of interest. Here we investigated the abundance of transcripts encodi...
Key message
Oxalotrophic Stenotrophomonas isolated from tomato rhizosphere are able to protect plants against oxalate-producing pathogens by a combination of actions including induction of plant defence signalling callose deposition and the strengthening of plant cell walls and probably the degradation of oxalic acid.
Abstract
Oxalic acid plays a...
BACKGROUND
Fruit dips in calcium ions solutions have been shown as an effective treatment to extend strawberries (Fragaria × ananassa, Duch) quality during storage. In the present work, strawberry fruit were treated with 10 g L⁻¹ calcium chloride solution and treatment effects on cell wall enzymes activities and the expression of encoding genes, as...
Senescence and degreening are the most important features that determine loss of quality during postharvest of broccoli. During senescence, chlorophylls are degraded with the purpose of avoiding presence of photoactive molecules. Chlorophyll b must be previously converted to chlorophyll a in order to be catabolized. This reduction process is cataly...
Modification of cell wall polymers composition and structure is one of the main factors contributing to textural changes during strawberry (Fragaria x ananassa, Duch.) fruit ripening and storage. The present study aimed to provide new data to understand the molecular basis underlying the postharvest preservation of strawberry cell wall structure by...
Background: Expansins play an important role in cell wall metabolism and fruit softening. Determination of expansin activity is a challenging problem since it depends on measuring cell wall properties by using ad hoc extensometers, a fact that has strongly restricted its study. Then, the objective of the work was to adapt a methodology to measure c...
Firmness, one of the major determinants of postharvest quality and shelf life of fruits is determined by the mechanical resistance imposed by the plant cell wall. Expansins (EXP) are involved in the non-hydrolytic metabolic disassembly of plant cell walls, particularly in processes where relaxation of the wall is necessary, such as fruit developmen...
Yellowing is the most evident symptom of senescence in green vegetables during postharvest storage. As chlorophyll synthesis is promoted by blue light, illumination would be a clean alternative to maintain healthier vegetables for longer. In this paper was assessed the effect of white-blue light-emitting diodes (WB LED) on outer and inner leaves (O...
Heat treatments cause a moderate and reversible stress that interrupts the normal metabolism (senescence or fruit ripening) of the product. Although there is a large number of reports about heat treatments on broccoli heads, the effect of subjecting only the stems to thermal treatments has not been studied yet. One of the main reasons to analyze th...
Due to its organoleptic and nutraceutical qualities, strawberry fruit (Fragaria x ananassa, Duch) is a worldwide important commodity. The role of ethylene in the regulation of strawberry cell wall metabolism was studied in fruit from Toyonoka cultivar harvested at white stage, when most changes associated with fruit ripening have begun. Fruit were...
α-L-arabinofuranosidases (EC 3.2.1.55) are enzymes involved in the catabolism of several cell-wall polysaccharides such as pectins and hemicelluloses, catalyzing the hydrolysis of terminal non-reducing α-L-arabinofuranosil residues. Bioinformatic analysis of the aminoacidic sequences of Fragaria x ananassa α-L-arabinofuranosidases predict a putativ...
Several cell wall enzymes are carbohydrate active enzymes that contain a putative Carbohydrate
Binding Module (CBM) in their structures. The main function of these non-catalitic modules is to
facilitate the interaction between the enzyme and its substrate. Expansins are non-hydrolytic
proteins present in the cell wall, and their structure includes...
Purpose of review: The goal of this review is to summarize the recent progress on the effects of UV radiation on fruits and vegetables metabolism.Main findings: Effective UV irradiation treatments can delay ripening and senescence, decrease decay and ameliorate the effects of chilling injury. The effects of the treatment on metabolism depend highly...
Loss of sugars contributes to accelerate postharvest senescence of broccoli. Several treatments have been devel-oped to delay senescence, but in many cases their effects on sugar metabolism were not analyzed. We studied the effect of harvest at different times of day (08:00, 13:00 and 18:00 h) and of several postharvest treatments as heat treatment...
Xyloglucan endotransglycosylase/hydrolase (XTH) enzymes are involved in the remodeling of plant cell wall hemicelluloses. With the aim to study the involvement of XTHs in strawberry fruit ripening, two cDNAs (FaXTH1 and FaXTH2) coding putative XTH proteins were cloned and the expression level of both genes was analyzed on different plant tissues an...
The fruit of the strawberry Fragaria×ananassa has traditionally been classified as non-climacteric because its ripening process is not governed by ethylene. However, previous studies have reported the timely endogenous production of minor amounts of ethylene by the fruit as well as the differential expression of genes of the ethylene synthesis, rec...
Broccoli is an important component of the human diet with a high nutritional value. This vegetable is harvested when its development is not complete, triggering a quick senescence that is accompanied by chlorophyll degradation and a shortening of shelf life. Recently it was shown that the time of the day at which the broccoli is harvested can influ...
Degreening caused by chlorophyll degradation is the most evident visual manifestation of broccoli senescence and deterioration. In this work, the effect of 1-MCP on color change, chlorophyll degradation and expression of genes associated to chlorophyll catabolism was evaluated during postharvest storage. 1-MCP treatment markedly delayed degreening...
A putative carbohydrate binding module (CBM) from strawberry (Fragaria × ananassa Duch.) expansin 2 (CBM-FaExp2) was cloned and the encoding protein was over-expressed in Escherichia coli and purified in order to evaluate its capacity to bind different cell wall polysaccharides "in vitro". The protein CBM-FaExp2 bound to microcrystalline cellulose,...
Lipoxygenases (LOX) belong to a large family of plant enzymes that catalyze the hydroperoxidation of polyunsaturated fatty acids. Most of them are expressed during senescence and contribute to membrane deterioration and biosynthesis of jasmonic acid, a known senescence enhancer. In this work, we cloned a fragment of a gene encoding a LOX from brocc...
Broccoli is a highly perishable vegetable that shows enhanced postharvest senescence and intense de-greening caused by chlorophyll degradation. One of the key steps of chlorophyll catabolism is the opening of chlorophyll tretrapyrrole catalysed by pheophorbide a oxygenase (PaO). In this study the expression of a gene encoding a putative PaO was cha...
Heat treatments have been applied in fruit postharvest technology for insect disinfestations, decay control, ripening delay and modification of fruit responses to other stresses. Heat treatment affects several aspects of fruit ripening, such as ethylene production and cell wall degradation probably through changes in gene expression and protein syn...
The removal of Mg2+ is an important step in the chlorophyll degradation pathway and extracts from senescent and presenescent Arabidopsis thaliana leaves were analyzed for Mg-dechelatase activity, using chlorophyllin, an artificial derivative of the natural substrate,
chlorophyllide. The optimum temperature and pH for this reaction were determined t...
Degradation of chlorophylls during senescence is a highly regulated process which requires the concerted action of several enzymes. Traditionally, it has been stated that the dismantling process of the chlorophyll molecule begins with a dephytilation step, followed by Mg(2+) removal and other breakdown reactions. Recently, new evidence suggests the...
Broccoli heads were harvested at different times of the day (sunrise, midday and sunset) and then stored at 20 °C for 5 d. The samples harvested at sunset showed the lowest loss of colour and chlorophyll degradation, those picked at dawn had the highest degreening, whereas heads harvested at midday showed an intermediate behaviour. As broccoli shel...
UV-C treatment is a new and environment-friendly strategy to reduce postharvest decay in several fruits. In this work, we studied the induction of resistance to Botrytis cinerea in strawberry fruit, exposed to a hormetic dose of UV-C. The results obtained showed that pre-storage treatment of fruit with UV-C results in lower losses caused by disease...
Broccoli (Brassica oleracea L.) is a rapidly perishable vegetable crop. Several postharvest treatments have been applied in order to delay de-greening. Since light has been shown to have an effect on pigment accumulation during development and darkness is known to induce senescence, the effect of continuous and periodic exposure to low-intensity wh...
Several treatments were applied in order to delay postharvest degreening in broccoli florets and investigate their effects on genes associated with chlorophyll catabolism. Degradation of chlorophylls is the most evident visual manifestation of broccoli postharvest deterioration, occurring rapidly due to the immature stage in which the material is h...
The Major Intrinsic Protein (MIP) family includes a main group of key channels known as aquaporins
(AQPs), described for sharing a very conservative structure with a pore that facilitates water and/or solute permeation. Since its
first member was functionally reported in 1992, AQPs were found to be abundantly expressed in all kingdoms. Although m...
Broccoli develops a fast senescence that deteriorates the nutritional quality of the product. In this work, a combined treatment with hot air and UV-C were applied to minimally processed broccoli florets to investigate their effects on the antioxidant system during storage at 20 °C. Application of UV-C and heat enhanced by approximately 13% the lev...
In strawberry, the putative participation of aquaporins should be considered during fruit ripening. Furthermore, the availability
of different firmness cultivars in this non-climacteric fruit is a very useful tool to determine their involvement in softening.
In a previous work, the cloning of a strawberry fruit-specific aquaporin, FaPIP1;1, which s...
To identify correlates of active syphilis infection among female sex workers (FSWs) in Tijuana and Ciudad Juarez.
Cross-sectional analyses of baseline interview data. Correlates of active syphilis (antibody titers >1 : 8) were identified by logistic regression. Setting Tijuana and Ciudad Juarez, two Mexican cities on the US border that are situated...
Broccoli is a horticultural product with a high nutritional value that can be consumed fresh but also minimally processed. However, broccoli is highly perishable since it develops a senescence quickly that deteriorates commercial and nutritional quality of the product. In this work we analysed the effect of a combination of UV-C and heat treatment...
Chilean strawberry (Fragaria chiloensis) is arising as a new fruit crop that can diversify the world supply of berries. Fruit softening is thought to be linked to an extensive modification of pectin and hemicellulosic cell wall fractions which in turn is determined to a great extent by the action of some cell wall-modifying enzymes. The objective o...
Strawberry is a soft fruit, considered as non-climacteric, being auxins the main hormones that regulate the ripening process. The role of ethylene in strawberry ripening is currently unclear and several studies have considered a revision of the possible role of this hormone.
Strawberry fruit were harvested at the white stage and treated with etheph...
A postharvest treatment with hot air (48 °C during 3 h) was applied to fresh-cut broccoli to investigate its effect on quality and senescence during storage at 0 °C. The treatment delayed yellowing as evidenced by lower decrease of Hue values during storage. After 21 days of storage, treated broccoli had chlorophyll content approximately 40% higher...
Expression and activity of cell wall modifying enzymes involved in fruit softening may be regulated by hormones and/or other signal molecules. In strawberry, FaXyl1 encodes for a fruit-specific β-xylosidase probably associated to hemicellulose degradation. In this work, we have isolated and analysed the promoter region of FaXyl1 gene. Analysis of t...
The Chilean strawberry fruit (Fragaria chiloensis) has potential as a new exotic berry. The rate of softening differs between F. chiloensis and its related species Fragaria×ananassa. The expression profiles of five expansin genes isolated from F.×ananassa were analyzed during softening of F. chiloensis fruit and the regulatory effect of auxins on t...
Strawberry (Fragaria × ananassa Duch.) fruit undergoes extensive softening during ripening due to cell wall disassembly, caused by a coordinated action of cell wall proteins and enzymes including polygalacturonases (PGs). The influence of plant growth regulators on PG activity and expression of the corresponding genes has been scarcely analyzed. In...
Softening of fleshy fruits during ripening is associated to catabolism of cell wall components. In strawberry, pectin degradation, as well as loss of neutral sugars (mainly arabinose), increases during ripening, and probably contributes to fruit softening. In this work, we report the activity of alpha-l-arabinofuranosidase (alpha-l-arafase) and the...
Exposure to UV-C delays fruit softening, one of the main factors determining fruit postharvest life. This softening delay might be caused by changes in the activities of enzymes and proteins involved in cell wall disassembly. Expansins, polygalacturonases (PGs), endoglucanases (EGs) and pectin-methylesterases (PMEs) are cell wall proteins or enzyme...
Since European settlement vast areas of the tall tussock grassland dominated by Paspalum quadrifarium Lam. and Paspalum exaltatum J. Presl (“pajonal” grassland) in the Flooding Pampa of Argentina were converted to croplands and short grasslands. With the use of Landsat satellite images, we analyzed current (1998-2000) cover and spatial integrity of...
Strawberries at white ripening stage were heat treated at 45°C for 3h in an air oven and then stored at 20°C for 72h. Firmness, activity of enzymes associated to cell wall degradation, and expression of related genes were determined during the storage. Fruit firmness decreased during the incubation time, and after 24h of storage the heat-treated fr...
Despite the advances in the physiology of fruit ripening, the role and contribution of water pathways are still barely considered. Our aim was therefore to characterize aquaporins, proteins that render the molecular basis for putative regulatory mechanisms in water transport. We focused our work on strawberry (Fragaria xananassa) fruit, a non-clima...
Combined treatments with hot air and UV-C were applied to minimally processed broccoli (Brassica oleracea L.) florets to investigate their effects on several quality and senescence parameters. To select the optimum treatment, florets were treated with three temperatures (42, 45 and 48 °C) for 3 h and three UV-C doses (5, 8 and 10 kJ m−2) in all com...
Fleshy fruits soften during ripening mainly as a consequence of the catabolism of cell wall components. In strawberry (Fragaria×ananassa Duch), the depolymerization and solubilization of pectins increase during ripening and contribute to fruit softening. In the present paper, we report the cloning and expression analysis of two polygalacturonase (P...
Minimally processed broccoli was treated with UV-C light (8 kJ m−2) and subsequently stored for 21 days at 4 °C. The UV-C treatment delayed yellowing and chlorophyll degradation during storage. Treated broccoli florets displayed lower electrolyte leakage and respiratory activity, indicating higher tissue integrity. Treated samples showed higher phe...
In this article we report the existence of chlorophyllase in strawberry fruit (Fragaria ananassa, Duch.). The enzyme was extracted from either fresh fruit or from acetone powder in the presence of Triton X-100 to improve its solubilization. The composition of the reaction mixture as well as the enzymatic activity conditions were optimized. At test...
Strawberry is a non-climateric fleshy fruit, which softens quickly and has short post-harvest life. Ripening is associated with an increment of pectin solubility and a reduction of the content of hemicelluloses. In this work, we have cloned the full-length cDNA encoding a β-xylosidase (FaXyl1) from Fragaria × ananassa and we have characterized its...
Strawberries (Fragaria × ananassa Duch., cv. Selva) were heat-treated in an air oven (45 °C, 3 h). After treatment, the fruit were stored at 0 °C for 0, 7 or 14 d, and then held for 2 d at 20 °C. Respiration rate, hydrogen peroxide level, potassium leakage, antioxidant capacity, ascorbic acid, superoxide dismutase (SOD), ascorbate peroxidase (APX)...
A hot air treatment was applied to broccoli (Brassica oleracea L. var. italica) florets and its effect on chlorophyll catabolism during postharvest senescence was analyzed. Florets were treated at 48 °C for 3 h and then placed in darkness at 20 °C. During storage, the yellowing of florets occurred simultaneously with a decrease in chlorophylls and...
Boysenberries (Rubus hybrid) were harvested at five developmental stages (green, “turning”, pink, red and purple) to study changes associated with flavour, colour and firmness, with a particular focus on the different enzymes involved in chlorophyll degradation or cell wall degradation.The level of reducing and non-reducing sugars increased 109- an...
Fruit softening is associated with cell wall disassembly mediated by the action of a complex set of enzymes and proteins. Expansins, a group of proteins with unknown enzymatic activity, are proposed to be involved in this process. In order to study the involvement of expansins in strawberry fruit softening we have analyzed the expression level of f...
Central broccoli heads (cv. de Cicco) were harvested and treated with UV-C light (4, 7, 10, or 14kJm−2). All treatments delayed yellowing and chlorophyll degradation at 20°C but the irradiation dose of 10kJm−2 allowed retaining the highest chlorophyll content yet had lower amounts of pheophytins than every treatment other than 7kJm−2. This dose was...
In the last decades considerable efforts have been sustained to develop alternative strategies to chemical methods to control postharvest diseases. One of such strategies has been the use of UV-C radiation. Postharvest UV-treatments consist in exposing the commodities for a certain period of time under a bank of UV lamps, with a maximal emission at...
Strawberries (75% red color) were harvested and heat-treated at 45 °C, 3 h in an air oven. After treatment, fruit were stored at 20 °C for 2 days. Firmness, content of cell wall components and activity of enzymes related to cell wall degradation was determined in the external and internal fruit zones of control or heat-treated fruit. Therefore, the...
Purpose of the review: The incidence of disease is a significant postharvest problem in soft fruit. This paper discusses traditional methods and emerging technologies used to control this problem.
Findings: Currently the most common approaches taken to reduce postharvest
spoilage of soft fruit are based on controlling the rate of fruit ripening and...
The knowledge of the distribution, area, and current conservation status of relict natural grasslands dominated by the tall-tussock grass Paspalum quadrifarium Lam. ("pajonal") in the Flooding Pampa (Argentina) is relevant for the identification of conservation sites and sustainable management and land-use planning. Since European settlement, vast...
Treatments with hot air were applied to broccoli (Brassica oleracea L) florets to investigate the effect on several quality and senescence parameters. To select the optimum treatment, florets were treated with different combinations of time/temperature ranging from 1 to 3 h and 37 to 50 °C and then placed in darkness at 20 °C. Most treatments delay...
Effects of ethephon and 6-benzylaminopurine (BAP) treatments on enzyme degrading enzymes and a peroxidase-linked chlorophyll bleaching were investigated in broccoli (Brassica oleracea L.) florets. The florets were dipped in solutions containing either BAP or ethephon and then incubated in darkness at 20 °C. The hue angle values and chlorophyll cont...
Peppers (Capsicum annum L. cv. Zafiro), having 90% red color, were treated with UV-C light (7 kJ m−2) and stored at 10 °C for 18 days. The UV-C treatment reduced decay. UV-C-treated peppers also kept firmer and presented lower carotenoid content and superficial color than control fruit. The treatments did not produce changes in fruit sugar content....
Fleshy fruit soften during ripening mainly as a consequence of solubilization and depolymerization of cell wall components. We have performed a comparative study of the polysaccharide content of fruit cell walls during final steps of development and ripening of three strawberry (Fragaria x ananassa Duch.) cultivars with different softening rates. T...
The effects of UV-C (4.1 kJ m−2) and heat treatment (45 °C, 3 h in air) either separately or combined on the quality of strawberries (Fragaria × ananassa cv Seascape) at the 75 or 50% surface red ripening stage were assessed, the latter stage being used only in the firmness test. In addition, the development of surface fungal infections was followe...
Mature boysenberries (Rubus hybrid) were harvested, heat-treated (45°C for 1 or 3 h or 47°C for 1 h) or exposed to UV-C light (2.3, 4.6 or 9.2 kJ m-2), and stored at 20°C for 2 d. Fruit treated with 9.2 kJ m-2 or 45°C for 1 h showed less damaged drupelets per fruit and/or remained firmer than untreated fruit after 2 d.Those treatments were selected...
Strawberry fruit shows a marked softening during ripening and the process is associated with an increment of pectin solubility and a reduction of the molecular mass of hemicelluloses. In this work, we report the activity of beta-xylosidase and the expression of a beta-xylosidase gene in strawberry fruit. We have cloned a cDNA fragment encoding a pu...
Criotecnología de Alimentos (CIDCA) UNLP-CONICET. 47 y 116 (B1900AJJ) La Plata, Argentina Abstract Strawberry is a rapidly decaying fruit and much of the postharvest research on strawberry is devoted to the development of methods to improve its postharvest shelf life. Physical treatments involving a low UV-C dose (4.6 kJ·m -2) and heat treatment (4...
On Feb 6, 2006 this sequence version replaced gi:42495031.
Strawberries (Fragaria ananassa cv Selva) were put in bags with different permeability to CO 2 , O 2 and H 2 O vapor, heat treated in an oven (45°C, 3h) and stored at 0°C for 0,7 or 14 days. When the treatment was finished, fruit was maintained at 20°C for 48h. The effect of heat treatment and films on fruit firmness, superficial color, anthocyanin...
Magnesium-dechelatase was obtained from strawberries (Fragaria × ananassa) by extraction with non-ionic detergents and concentrated by ammonium sulfate fractionation. Extracts with Mg-dechelatase activity were dissolved in high or low ionic strength and their heat stability and capacity to filtrate through 10-kDa cut-off membranes were analyzed. At...
Peroxidase (POX) from strawberry fruits was analyzed for its capacity to bleach chlorophyll. The partially purified enzyme preperation catalyzed the bleaching of chlorophylls and their derivatives in the presence of H(2)O(2) and phenolic compounds. The optimal reaction conditions were 35 degrees C, pH 5.2 and ionic strength equal to 0.2. The maximu...
This work analyzes the consequences of combining heat treatment with refrigerated storage in strawberry fruit. Strawberries cv. Selva were heat treated in an oven (45°C, 3h) and stored at 0°C for 0,7 or 14 days. Afterwards, fruits were maintained at 20°C for 48h. The effect of the treatment on texture, surface color, anthocyanins, acidity, sugars,...
Peroxidase (POX) from strawberry fruits was analyzed regarding its capacity to bleach chlorophyll; it catalyzed the bleaching of chlorophylls (Chls) and their derivatives in the presence of H2O2 and phenolic compounds. The optimum reaction conditions were 35°C, pH 5.2, ionic strength 0.2, and 1 mM H2O2. Compounds with high affinity for the heme gro...
In this work, polyphenoloxidase (PPO) from Selva strawberry fruit (Fragaria × ananassa, Duch) was extracted, characterised and partially purified. The activity of PPO was analysed in crude extracts obtained from either fresh fruits or acetone powder. The presence of NaCl and Triton X-100 in the extraction buffer caused a marked increase in enzyme e...
Fully red strawberries (Fragaria × ananassa Duch. cv. Selva) were treated for 1−5 h at temperatures ranging from 39 to 50 °C. After treatments, fruits were placed at 0 °C overnight and then held at 20 °C for 3 days. Most of the heat treatments improved strawberry shelf life, with best results obtained for fruit heated at 42 °C and 48 °C for 3 h. He...
The effect of exogenously applied gibberellic acid (GA3) on the postharvest color change of strawberry fruit was evaluated through their external color and surface color parameters.
A significant delay on color evolution was observed in fruits treated with GA3. The evolution of activities of phenylalanine ammonia-lyase (PAL), chlorophyllase, and pe...
In this work, peroxidase from strawberry fruit was detected, partially purified, and characterized. The total enzyme extract (both soluble and associated to membranes) was partially purified by means of (NH4)(2)SO4 precipitation, molecular exclusion chromatography, and cationic exchange chromatography. The purification grade achieved was near 35. E...
Effect of GA3 on postharvest ripening in strawberry fruit was evaluated through different biochemical parameters. Strawberry slices at
different ripening stages were incubated with GA3. A significant decrease on respiratory activity depending on GA3 concentration was obtained. Also GA3 was applied to whole and deachened fruit at white and green rip...
abstract Exposure to UV-C delays fruit softening, one of the main factors determining fruit postharvest life. This
