Eco-safe composite edible coating of hydrocolloids with papaya leaf extract improves postharvest quality and shelf life of papaya fruit under ambient storage.

Papaya postharvest management using low-temperature storage is discouraged as it is a tropical fruit. Extensive research is going on to preserve papaya quality at ambient storage using edible coatings and its composites. The present investigation examined the effects of an eco-safe composite edible coating consisting of hydrocolloid carboxymethyl cellulose (CMC) (1%), guar gum (1.5%), xanthan gum (0.3%), and Gum Arabic (10%) combined with papaya leaf extract (PLE) (1:1 ratio by volume) applied as dip treatment on "Red Lady" papaya fruit at ambient storage condition. Among all the attempted treatments, "PLE incorporated with CMC (1%)" was found to be the best, as the treated fruit exhibited the highest levels of biochemicals, whereas the lowest levels of physiological and enzymatic activity, which positively affected the shelf life. The "CMC + PLE" treatment enhanced the fruit gloss score by 70.1%, phenolics by 6.1%, ascorbic acid by 22.3%, total carotenoid content by 7.4%, and fruit predilection score by 22.0% over the control fruit. However, it lowered (controlling) the physiological loss in weight by 51.0%, decay incidence by 66.6%, and polygalacturonase and pectin methylesterase activity by 24.92% and 35.29%, respectively, over control. Moreover, this treatment exhibited the highest fruit purchase predilection score and prolonged the storage life for >3 days on the physiological loss standard basis (≤10%). This study indicates that "CMC (1%) with PLE (1:1)" composite coating application on papaya under ambient conditions might be an effective, environmentally friendly, and health-friendly way to retain the quality and extend the storage life.

Spatial and Compositional Variations in Fruit Characteristics of Papaya (Carica papaya cv. Tainung No. 2) during Ripening.

Papaya fruit (Carica papaya) has different degrees of ripening within each fruit, affecting its commercial market value. The fruit characteristics of "Tainung No. 2" Red papaya were investigated at the stem-end, middle, and calyx-end across 3 ripening stages and categorized based on fruit skin coloration: unripe at 16 weeks after anthesis (WAA), half-ripe at 18 WAA, and full-ripe at 20 WAA. The fruits maintained an elliptical shape during ripening with a ratio of 2.36 of the length to the width. The peel and pulp color changed from green to white to yellow during ripening, regardless of the three parts. In the pulp, soluble solid contents increased, and firmness decreased during ripening but did not differ among the three parts. Individual nutrient contents, including metabolites and minerals, changed dynamically between the ripening stages and fruit parts. Total carbohydrates and proteins, N, and K, were accumulated more at the stem-end during ripening; meanwhile, fructose, glucose, Mg, and Mn were accumulated more at the calyx-end. In the principal component analysis, ripening stages and fruit parts were distinctly determined by the first and second principal components, respectively. Understanding the nutrient and metabolite dynamics during ripening and their distribution within the fruit can help optimize cultivation practices, enhance fruit quality, and ultimately benefit both growers and consumers.

Mate Selection on Anastrepha curvicauda: Effect of Weight, Age, and Virginity.

Sexual selection determines the evolution of the species by favoring some attributes that confer a reproductive advantage to those individuals with those attributes. Tephritidae flies do not always select the same traits when looking for a mating partner. Some aspects of the mating system of Anastrepha curvicauda are known; nevertheless, there is no information on the effect of age, size, and virginity when selecting a mating partner. We set up a series of experiments where a selector (male or female) may select between (a) an old or young partner, (b) a small or large partner, and (c) a virgin or mated partner. Males of A. curvicauda significantly preferred large, young, and virgin females, while females showed no preference for high- or low-quality males. The females' non-preference for a particular male is discussed in the light of their mating system.

Alteration of surface morphologies and chemical composition of cuticle in response to chilling injury in papaya (Carica papaya L.) after harvest.

The alteration of surface microstructures and chemical composition in cuticle of papaya fruit in response to chilling stress were comparatively studied between cultivars of 'Risheng' and 'Suihuang' after harvest. Fruit surface was covered by fissured wax layers in both cultivars. The presence of granule crystalloids was cultivar dependent, with higher abundance in 'Risheng' and lower in 'Suihuang'. Various typical very-long-chain aliphatics i.e., fatty acids, aldehydes, n-alkanes, primary alcohols, and n-alkenes dominated waxes; and cutin monomers were prominently 9/10,16-dihydroxyhexadecanoic acid in papaya fruit cuticle. Chilling pitting symptom was accompanied by modification of granule crystalloids into flat appearance and decreased primary alcohols, fatty acids, and aldehydes in 'Risheng', but no evident changes in 'Suihuang'. The response of cuticle to chilling injury in papaya fruit might be not directly related to the overall amount of waxes and cutin monomers, but more likely to the alteration of appearance morphologies and chemical composition in cuticle.

Abnormal chilling injury of postharvest papaya is associated with the antioxidant response.

Generally, the lower the temperature and/or the longer the duration of low temperature, the more serious chilling injury (CI) symptom appears in fruit. However, our previous study showed that the higher storage temperature (6°C) resulted in a more serious CI in papaya fruit compared to that stored at 1°C, which could be viewed as an abnormal CI behavior. This study investigated the antioxidant responses that existed in abnormal CI behavior of papaya fruit. Compared to 6°C, antioxidant enzyme activities of papaya fruit which was stored at 1°C were maintained at a higher level while the circulatory metabolism of the ascorbate-glutathione cycle (AsA-GSH) was more vigorous in papaya fruit, as indicated by higher superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR) activities and higher AsA and GSH levels, which could reduce the superoxide anion (·O2 - ) production rate and the hydrogen peroxide (H2 O2 ) content. Suppressed reactive oxygen species (ROS) generation in papaya fruit at 1°C resulted in reduced membrane permeability and malondialdehyde (MDA) accumulation when compared to that at 6°C, thus the development of CI was restricted during storage at 1°C. This study deepened the understanding of differential antioxidant responses during cold storage at 1°C and 6°C in papaya fruit and provided a theoretical basis for further study on the mechanism of the abnormal CI behavior in papaya fruit. PRACTICAL APPLICATIONS: Low-temperature storage is one of the most effective methods to preserve fruit and vegetable products. While, inappropriate low temperature could induce CI, and the damage caused by CI is often more serious than estimated. Therefore, it is necessary to study the physiological and biochemical characteristics of different postharvest fruits and vegetables to prolong storage period, improve storage quality and reduce the loss of products. This study analyzed the antioxidant reaction in abnormal CI behavior of papaya, which could contribute to the further study on the mechanism of CI in papaya fruit and provide theoretical basis for the development of preservation technology of papaya fruit.

Abnormal behavior of chilling injury in postharvest papaya fruit is associated with sugar metabolism.

In the most chilling-sensitive fruits and vegetables, usually, the lower the storage temperature, the more serious the symptoms of chilling injury (CI). As one of the special cases, papaya fruits at 1℃ show slighter CI symptoms than those at higher storage temperature. Such abnormal CI phenomenon has not received enough attention and its mechanism is not clear. The present study investigated the difference of CI severity and sugar metabolism in papaya fruits when stored between 1℃ and 6℃. The results showed that CI index in papaya fruits preserved at 1°C was markedly lower than that in fruit at 6°C, which was accompanied by higher content of glucose, fructose, and sucrose. In addition, compared to 6°C, 1°C promoted higher activities of sucrose synthase, sucrose-phosphate synthase, and neutral invertase, but lowered acid invertase activity. RT-qPCR analysis showed that 1°C upregulated the CpSPS expression and downregulated the CpAI expression when compared to 6°C. The present results indicate that higher chilling tolerance in papaya fruit at 1°C could be attributed to more accumulation of sucrose and reducing sugars in relation to more advantageous sugar metabolism. These results provided a basis for explaining the abnormal behavior of papaya fruits in response to varying low temperatures. PRACTICAL APPLICATION: For most chilling-sensitive fruits and vegetables, in the range of temperatures that induce chilling injury (CI), the lower storage temperature may lead to more severe CI. However, as one of the special cases, papaya fruits at 1℃ show slighter CI symptoms than those at higher storage temperature. The reason for this abnormal CI symptom in papaya fruits is that 1°C storage can regulated enzyme activities and changes in gene expression related to sugar metabolism, which could result in more accumulation of sucrose and slower degradation of hexose and contribute to alleviation of CI. Our results provided a basis for explaining the abnormal behavior of papaya fruit in response to varying low temperatures.

Coactive role of zinc oxide nanoparticles and plant growth promoting rhizobacteria for mitigation of synchronized effects of heat and drought stress in wheat plants.

This study intended to investigate the potential of the plant growth-promoting rhizobacteria (PGPR) and green synthesized zinc oxide nanoparticles (ZnO-NPs) (fruit extract of Papaya) against heat and drought stress in wheat. The characterization of green-synthesized ZnO-NPs was done through UV-vis spectrophotometry, Fourier-transform infrared spectrometry, X-ray diffraction and scanning electron microscopy. Individual and combination of PGPR (Pseudomonas sp.) and ZnO-NPs (10 ppm) amendments were tested in a pot experiment to upregulate wheat defence system under three stress groups (drought, heat and combined heat and drought stress). Drought and heat stress synergistically caused higher damage to wheat plants than individual heat and drought stress. This observation was confirmed with remarkable higher MDA and hydrogen peroxide (H2O2) content. Treated plants exposed to all stress groups showed an improved wheat growth and stress resistance through better biomass, photosynthetic pigments, nutrients, soluble sugars, protein and indole acetic acid content. Combination of ZnO-NPs and Pseudomonas sp. Protects the plants from all stress groups by producing higher proline, antioxidant enzymes i. e superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase, and abscisic acid. Moreover, higher stress alleviation by this treatment was manifested by marked reduced electrolyte leakage, MDA and H2O2. The findings of current study confirmed that the synergistic actions of PGPR and ZnO-NPs can rescue plants from both single and combined heat and drought stress.

Effect of Ultrasound-Assisted Extraction of Carotenoids from Papaya (Carica papaya L. cv. Sweet Mary) Using Vegetable Oils.

By-products from fruits and are of great interest for their potential use in the food industry due to their high content of bioactive compounds. Herein, we examined the ultrasound-assisted extraction (UAE) of carotenoid and carotenoid esters from papaya pulp and peel using soybean oil and sunflower oil as alternative green solvents. Response surface methodology (RSM) was established to optimize the UAE process. Three independent variables, ultrasonic amplitude (20-60%), time (10-60 min), and co-solvent percentage (ethanol) (5-20%, v/v), were applied. The highest total carotenoid content in the UAE extracts was obtained from papaya pulp extracts (58.7 ± 1.6 and 56.0 ± 1.5 µg carotenoids/g oil) using soybean oil and sunflower oil, respectively (60% amplitude/ 10 min/ 20% ethanol). On the other hand, the highest carotenoid content (52.0 ± 0.9 µg carotenoids/g oil) was obtained from papaya peel using soybean oil applying the UAE process (20% amplitude/ 77 min/ 20% ethanol); a minor content of 39.3 ± 0.5 µg carotenoids/g oil was obtained from papaya peel using sunflower oil at 60% amplitude/ 60 min/ 5% ethanol. Lycopene was the most abundant carotenoid among all individual carotenoids observed in papaya oil extracts, obtaining the highest yields of this carotenoid when papaya pulp and peel were extracted using soybean oil (94% and 81%, respectively) and sunflower oil (95% and 82%, respectively). Great extraction of xanthophyll esters was detected using 20% of ethanol in the vegetable oil extraction solvent (v/v). High correlations (>0.85) was obtained between total carotenoid content and color determination in the UAE oil extracts. UAE vegetable oil extracts enriched with carotenoids from papaya by-products could be useful to formulate new food ingredients based on emulsions with interesting potential health benefits.

Optimal surveillance against bioinvasions: a sample average approximation method applied to an agent-based spread model.

Trade-offs exist between the point of early detection and the future cost of controlling any invasive species. Finding optimal levels of early detection, with post-border active surveillance, where time, space and randomness are explicitly considered, is computationally challenging. We use a stochastic programming model to find the optimal level of surveillance and predict damages, easing the computational challenge by combining a sample average approximation (SAA) approach and parallel processing techniques. The model is applied to the case of Asian Papaya Fruit Fly (PFF), a highly destructive pest, in Queensland, Australia. To capture the non-linearity in PFF spread, we use an agent-based model (ABM), which is calibrated to a highly detailed land-use raster map (50 m × 50 m) and weather-related data, validated against a historical outbreak. The combination of SAA and ABM sets our work apart from the existing literature. Indeed, despite its increasing popularity as a powerful analytical tool, given its granularity and capability to model the system of interest adequately, the complexity of ABM limits its application in optimizing frameworks due to considerable uncertainty about solution quality. In this light, the use of SAA ensures quality in the optimal solution (with a measured optimality gap) while still being able to handle large-scale decision-making problems. With this combination, our application suggests that the optimal (economic) trap grid size for PFF in Queensland is ˜0.7 km, much smaller than the currently implemented level of 5 km. Although the current policy implies a much lower surveillance cost per year, compared with the $2.08 million under our optimal policy, the expected total cost of an outbreak is $23.92 million, much higher than the optimal policy of roughly $7.74 million.

Metabolome and proteome of ethylene-treated papayas reveal different pathways to volatile compounds biosynthesis.

Papayas undergo fast postharvest changes triggered by the plant hormone ethylene. Some important pathways have been analyzed in limited studies (transcriptomics and targeted metabolomics); however, broad use of proteomics or untargeted metabolomics have not yet been used in papayas. In this study, two groups of green papayas (150 days after anthesis-physiological maturity for papayas) were treated with ethylene at different times (6 and 12 h) and their metabolic changes in fruit pulp were evaluated with untargeted metabolomics (general metabolites and volatile compounds) and proteomics. Polar metabolites exhibited distinct patterns, especially with regard to some amino and fatty acids during stimulated ripening. In particular, glutamate increased through a possible gamma aminobutyric acid (GABA) shunt and/or proteases activity. Moreover, the stimulated ripening altered the volatile compounds and the protein profiles. The results suggest that changes in membrane breakdown and the resulting oxidative processes could be responsible for volatile compound production, altering some sensorial qualities of papayas, such as pulp softening and the specific papaya linalool volatile compound increment. Thus, GABA levels could also be a strong biological marker for papaya development and ripening stages. This study applied two "omic" techniques that provided insight into how the plant hormone ethylene could influence papaya postharvest quality.

Effect of glycine betaine on chilling injury in relation to energy metabolism in papaya fruit during cold storage.

"Zhongbai" papaya fruit were treated with 15 mmol/L glycine betaine (GB) and then refrigerated at 6°C for 40 days to study the influence of GB on chilling injury (CI) and possible mechanism associated with energy metabolism. The results exhibited that GB treatment remarkably reduced the CI severity as indicated by lower CI index during storage. GB treatment lowered electrolyte leakage and malondialdehyde content, which accounted for maintenance of membrane integrity and reduced lipid peroxidation. Moreover, GB treatment improved the energy status as revealed by increased adenosine triphosphate (ATP) level, energy charge, and activities of energy metabolism-related enzymes including mitochondrial membrane H+-adenosine triphosphatase (H+-ATPase) and Ca2+-adenosine triphosphatase (Ca2+-ATPase), succinate dehydrogenase (SDH), and cytochrome C oxidase (CCO). The results indicate that enhanced chilling tolerance in papaya fruit by GB treatment during cold storage might be ascribed to improved energy status in association with increased activities of energy metabolism-related enzymes.

High hydrostatic pressure treatments trigger de novo carotenoid biosynthesis in papaya fruit (Carica papaya cv. Maradol).

High hydrostatic pressure (HHP) processing is a non-thermal technology reported to increase desirable metabolites in plant foods. This work evaluated changes in carotenoid accumulation in fresh-cut papaya fruit as affected by HHP treatment (50-400 MPa for 3-60 min) and during subsequent storage at 4 °C; simultaneously, transcriptional activities of carotenoid biosynthetic genes and oxidative stress markers were evaluated. LC-MS analyses revealed that HHP treatment increased carotenoid precursors and carotenes contents following processing and storage: lycopene levels increased up to 11-fold compared to the non-treated samples, and H2O2 and lipid peroxidation were concomitantly increased. qRT-PCR of intact RNA showed that the amount of phytoene desaturase transcripts increased after HHP treatment, and that they were correlated with carotene accumulation. This is the first study to show that HHP treatment triggers de novo carotenoid biosynthesis, which is regulated at the transcriptional level, possibly by inducing oxidative stress signaling in fruit tissue.

Reduction of papaya rot (Phytophthora palmivora) with phosphite and Acibenzolar-S-Methyl in preharvest and postharvest / Redução da podridão do mamão (Phytophthora palmivora) com fosfitos e Acibenzolar-S-Metil em pré e pós-colheita

The papaya fruit rot (Phytophthora palmivora) is responsible for significant losses. To reduce diseases, especially in areas with climate and humidity favorable to pathogens, are adopted chemical methods, which sometimes increase the cost of production and cause severe environmental impacts. Alternatively, there are products, such as, phosphites of potassium and acibenzolar-S-methyl (ASM) that might be efficient on disease control and less aggressive to environment. Phosphites of K and ASM were evaluated in this study on the control effectiveness of papaya fruit rot at different dosages in preharvest and postharvest. The severity and percentage of disease control were evaluated for each treatment. For the pre-harvest treatments (applied six days before harvest), the phosphite of K [240 g L-1 K2O, 340 g L-1 P2O5 and 50 g L-1 (Reforce® + Salicylic Acid)] at 3 or 6 mL L-1significantly reduced disease severity, and, reduced fruit ripening. On postharvest application, ASM reduced disease severity.

A podridão dos frutos do mamoeiro (Phytophthora palmivora) é responsável por perdas significativas e para minimizar a doença, principalmente em locais com clima favorável ao patógeno, medidas de controle químico são adotadas. Porém, estas medidas podem elevar o custo da produção e causar severos impactos ambientais. Alternativamente, existem produtos como os fosfitos de potássio (K) e acibenzolar-S-metil (ASM) que podem ser eficientes no controle de doenças e menos agressivos ao ambiente. Fosfitos de K e ASM foram avaliados neste trabalho quanto à eficácia do controle da podridão de frutos de mamão 'Sunrise Solo' tipo exportação, cultivados no Sul da Bahia, em diferentes doses e formulações comerciais na pré e pós-colheita. Para cada tratamento foi avaliada a severidade da doença e o percentual de controle da doença, sendo também verificada a influência nas características fisioquímicas na fruta. Para os tratamentos pré-colheita, aplicados aos seis dias antes da colheita, o fosfito de K [240 g L-1 K2O, 340 g L-1 P2O5 e 50 g L-1 C7H6O3 (Reforce® + Ácido Salicílico)] a 3 ou 6 mL L-1 reduziu significativamente a doença, e influenciou diretamente no atraso da maturação da fruta. Na pós-colheita, ASM incitou redução na severidade da doença. Todos os tratamentos não alterarão as características fisioquímicas da fruta.

Optimization of red teff flour, malted soybean flour, and papaya fruit powder blending ratios for better nutritional quality and sensory acceptability of porridge.

This study was carried out to optimize the compositions of red teff flour with malted soybean flour and papaya fruit powders for better nutritional quality and sensory acceptability of porridge. Total eleven formulations of the composite flours were determined using D-optimal mixture design with the help of Minitab Version 16 Statistical Software. The three ingredients were considered in the ranges of 55%-70%, 20%-30%, 5%-15% for red teff flour, malted soybean flour, and Papaya fruit powder, respectively. The prepared porridge samples from formulations were analyzed for nutritional composition, antinutritional factors, and sensory acceptability. Results of the study showed the significant difference (p < .05) in ash, fat, fiber, protein, carbohydrate, energy, iron, calcium, zinc, ß-carotene, phytates, tannin, appearance, taste, mouthfeel, and overall acceptability as the composition of ingredients were changed. The overall optimum point was found in a range of red teff flour (60%-70%), malted soybean flour (20%-27.5%), and papaya fruit powder (10%-12.5%). In conclusion, the present approach can help in improve infants dietary quality of complementary foods by developing nutritionally enhanced red teff-based porridge used for intervention of malnutrition.

Papaya CpEIN3a and CpNAC2 Co-operatively Regulate Carotenoid Biosynthesis-Related Genes CpPDS2/4, CpLCY-e and CpCHY-b During Fruit Ripening.

Papaya is an important tropical fruit with a rich source of carotenoids. The ripening of papaya is a physiological and metabolic process with remarkable changes including accumulation of carotenoids, which depends primarily on the action of ethylene. Ethylene response is mediated by a transcriptional cascade involving the transcription factor families of EIN3/EILs and ERFs. Although ERF members have been reported to control carotenoid production in Arabidopsis and tomato, whether EIN3/EILs are also involved in carotenoid biosynthesis during fruit ripening remains unclear. In this work, two EIN3 genes from papaya fruit, namely CpEIN3a and CpEIN3b, were studied, of which CpEIN3a was increased during fruit ripening, concomitant with the increase of transcripts of carotenoid biosynthesis-related genes including CpPDS2/4, CpZDS, CpLCY-e and CpCHY-b, and carotenoid content. Electrophoretic mobility shift assays (EMSAs) and transient expression analyses revealed that CpEIN3a was able to bind to the promoters of CpPDS4 and CpCHY-b, and promoted their transcription. Protein-protein interaction assays indicated that CpEIN3a physically interacted with another transcription factor CpNAC2, which acted as a transcriptional activator of CpPDS2/4, CpZDS, CpLCY-e and CpCHY-b by directly binding to their promoters. More importantly, the transcriptional activation abilities of CpPDS2/4, CpLCY-e and CpCHY-b were more pronounced following their interaction. Collectively, our findings suggest that CpEIN3a interacts with CpNAC2 and, individually or co-operatively, activates the transcription of a subset of carotenoid biosynthesis-related genes, providing new insights into the regulatory networks of carotenoid biosynthesis during papaya fruit ripening.

Subchronic Immunotoxicity Assessment of Genetically Modified Virus-Resistant Papaya in Rats.

Papaya is an important fruit that provides a variety of vitamins with nutritional value and also holds some pharmacological properties, including immunomodulation. Genetically modified (GM) papaya plants resistant to Papaya ringspot virus (PRSV) infection have been generated by cloning the coat protein gene of the PRSV which can be used as a valuable strategy to fight PRSV infection and to increase papaya production. In order to assess the safety of GM papaya as a food, this subchronic study was conducted to assess the immunomodulatory responses of the GM papaya line 823-2210, when compared with its parent plant of non-GM papaya, Tainung-2 (TN-2), in Sprague-Dawley (SD) rats. Both non-GM and GM 823-2210 papaya fruits at low (1 g/kg bw) and high (2 g/kg bw) dosages were administered via daily oral gavage to male and female rats consecutively for 90 days. Immunophenotyping, mitogen-induced splenic cell proliferation, antigen-specific antibody response, and histopathology of the spleen and thymus were evaluated at the end of the experiment. Results of immunotoxicity assays revealed no consistent difference between rats fed for 90 days with GM 823-2210 papaya fruits, as opposed to those fed non-GM TN-2 papaya fruits, suggesting that with regard to immunomodulatory responses, GM 823-2210 papaya fruits maintain substantial equivalence to fruits of their non-GM TN-2 parent.

The Papaya Transcription Factor CpNAC1 Modulates Carotenoid Biosynthesis through Activating Phytoene Desaturase Genes CpPDS2/4 during Fruit Ripening.

Papaya fruits accumulate carotenoids during fruit ripening. Although many papaya carotenoid biosynthesis pathway genes have been identified, the transcriptional regulators of these genes have not been characterized. In this study, a NAC transcription factor, designated as CpNAC1, was characterized from papaya fruit. CpNAC1 was localized exclusively in nucleus and possessed transcriptional activation activity. Expression of carotenoid biosynthesis genes phytoene desaturases (CpPDSs) and CpNAC1 was increased during fruit ripening and by propylene treatment, which correlates well with the elevated carotenoid content in papaya. The gel mobility shift assays and transient expression analyses demonstrated that CpNAC1 directly binds to the NAC binding site (NACBS) motifs in CpPDS2/4 promoters and activates them. Collectively, these data suggest that CpNAC1 may act as a positive regulator of carotenoid biosynthesis during papaya fruit ripening possibly via transcriptional activation of CpPDSs such as CpPDS2/4.

Induction of the expression of defence genes in Carica papaya fruit by methyl jasmonate and low temperature treatments

The defence mechanisms that are activated by methyl jasmonate (MJ) in fruits are not well understood. In this work, we studied the expression of defence genes in papaya fruit that are induced by the exposure to MJ and/or low temperatures. The papaya fruits ‘Maradol’ were randomly divided into two groups: one group was the untreated control and the other was treated with 10-4 M of MJ. Half of the fruits from each of the two groups were stored after treatment for 5 days at 5ºC and 2 days at 20ºC. We studied the expression levels of the pdf1.1 and pdf1.2 genes by amplification from expression libraries created from the pulp and skin tissues of the papaya fruit. As a reference, the mRNA level of the 18s ribosomal gene was used. In the skin tissue, the expression levels of the pdf1.1 and pdf1.2 genes were higher immediately after MJ treatment compared to the control. Furthermore, the expression of pdf1.2 remained high after MJ treatment and subsequent storage compared to the control. It was therefore concluded that the activation of the pdf1.1 and pdf1.2 genes forms part of the molecular defence mechanism in fruits that is activated by exposure to MJ. To our knowledge, this is the first study that analyzes the gene expression in papaya fruit that is induced by the exogenous application of methyl jasmonate and cold treatment.

Antioxidant and immunostimulant effect of carica papaya linn. Aqueous extract in acrylamide intoxicated rats.

INTRODUCTION: The present study was conducted to evaluate the antioxidant and immunostimulant effects of The Carica papaya fruit aqueous extract (CPF, Caricaceae) against acrylamide induced oxidative stress and improvement of Immune functions which affected by free radicals liberating acrylamide in rats. MATERIAL AND METHODS: Sixty male wistar albino rats (195-230g) were assigned to four groups, (fifteen/group). The first group used as control group and received normal physiological saline orally daily. The second group was supplemented with acrylamide 0.05% in drinking water. The third group was gastro-gavaged with 250 mg/kg of papaya fruit extract orally on daily basis. The fourth group was supplemented with acrylamide 0.05% in drinking water and gastro-gavaged with 250 mg/kg of papaya fruit extract orally on daily basis. The chosen dose of papaya fruit extract was based on the active pharmacological dose range obtained from the orientation study earlier conducted. The experimental period was extended to forty day. At the expiration of the experimental period and night fasting, blood samples were collected from the orbital venous sinus. The sera were separated and used for determining of IgG and IgM and the stomach, liver and kidney homogenates for estimation of MDA, GSH level, SOD and CAT activity as a biomarker of lipid peroxidation and antioxidative stress. RESULTS AND DISCUSSION: The obtained results revealed that, acrylamide caused significant increases in MDA and decrease of GSH level, SOD and CAT activity due to the oxidative stress induced by acrylamide on membrane polyunsaturated fatty acids in rat's stomach, liver and kidney while administration of CPF aqueous extract, was significantly ameliorated the increased levels of MDA and decline of GSH, SOD and CAT activity in the stomach, liver and kidney tissues caused by acrylamide toxicity. Meanwhile, CPF aqueous extract significantly increased immune functions (IgG and IgM) while acrylamide significantly decrease it specially IgG. Thus, this study suggests that acrylamide-induced oxidative stress in rats can be ameliorated by administration of CPF aqueous extract.