Accumulation of Scoparone in Heat-Treated Lemon Fruit Inoculated with Penicillium digitatum Sacc

Phytoalexin scoparone (6,7-dimethoxycoumarin) generally was not detected in noninoculated lemon fruit (Citrus limon [L.] Burm., cv Eureka) but accumulated in fruit after inoculation with Penicillium digitatum Sacc. A much greater increase in the amount of scoparone was found in fruit exhibiting an incompatible response to Penicillium after heat treatment at 36°C for 3 days. Heat treatment prevented development of decay in the inoculated fruit. The concentration of the compound after inoculation continued to increase during and after the heat treatment period, reaching 178 micrograms per gram fresh weight of the flavedo 6 days after the heat treatment. Changes in scoparone concentration in fruit were closely correlated with the changes in the antifungal activity of the fruit extract. A low concentration of the phytoalexin was detected in fruit injured mechanically. Scoparone also accumulated in the fruit following ultraviolet illumination; the concentration of the compound was dose-dependent. Median effective dose values of the inhibition of germ tube elongation and spore germination of P. digitatum were 29 and 46 micrograms per milliliter, respectively. Our findings suggest that the rapid increase in scoparone concentration plays an important role in the increased resistance of heat-treated lemon fruit to infection by P. digitatum.     

Involvement of ethylene biosynthesis and perception in the susceptibility of citrus fruits to Penicillium digitatum infection and the accumulation of defence-related mRNAs

Citrus fruits infected with the fungus Penicillium digitatum substantially increase the production of the plant hormone ethylene. In this study, the regulation of ethylene biosynthesis in Citrus sinensis-infected fruits and its putative involvement in an active defence response against P. digitatum infection is examined. Ethylene production is demonstrated as being the result of the co-ordinated and differential up-regulation of at least three ethylene biosynthetic genes: ACS1, ACS2, and ACO. Blocking ethylene perception by 1-MCP resulted in an increased ethylene production and ACS2 expression during infection and mechanical wounding, suggesting that this gene is negatively regulated by ethylene. ACO expression was induced by ethylene in the absence of wounding or infection, although further results indicate that its induction during the course of infection may not be primarily mediated by ethylene. Treatment with 1-MCP also increased susceptibility to Penicillium decay, showing an involvement of ethylene perception in promoting defence responses in citrus fruits. The changes in the expression of two defence-related genes up-regulated during infection were also studied: the ones coding for phenylalanine ammonia-lyase (PAL) and an acidic class II chitinase (ACR311). The onset of PAL expression after mechanical wounding or inoculation was not changed in 1-MCP-pretreated fruits, while its later increase during the course of infection was abolished. Chitinase gene induction was more related to mechanical damage and was partially repressed by ethylene. These studies indicate distinct possible regulatory mechanisms of plant fruit defence genes in the context of fungal infection and ethylene perception.     

Preference and performance of peach fruit fly (Bactrocera Zonata) and Melon fruit fly (Bactrocera Cucurbitae) under laboratory conditions

In Pakistan and all over the world, the Peach Fruit Fly (PFF), Bactrocera zonata (Saunders.) and the Melon Fruit Fly (MFF), Bactrocera cucurbitae (Coquillett.) are considered severe and polyphagous insect pests for various fruits and vegetables. The current study was conducted to check the Laboratory preference and performance of B. cucurbitae and B. zonata on selected Fruits Citrus (Citrus sinensis), Apple (Malus domestica), Banana (Musa acuminate), and vegetable, Sponge gourd (luffa aegyptiaca), Bitter gourd (Momordica charantia) Pumpkin (Cucurbita moschata) under laboratory conditions. The study showed that Sponge Gourd was the preferable host with the mean pupae resurgence of (242.33), followed by Bitter Gourd (78.333) among selected vegetables. At the same time, among fruits, a banana was the preferable host with mean pupae resurgence (204.33), followed by orange (158.33). The pumpkin and apple was the least preferable host for both B. cucurbitae and B. zonata, with mean pupae resurgence (35.667) and (79.000), respectively. Furthermore, the study showed that Banana was the preferable host for B. Zonata among intact and infested fruits, whereas B. cucurbitaee showed the most preference to Bitter gourd among intact and infested vegetables showing significantly different results among intact and infested fruits and vegetables. Maximum number of eggs, pupa, female flies, male flies, adult emergence from pupa (flies) and period of pupa of B. zonata and B. cucurbitae on banana and bitter gourd. While, other fruits and vegetables showed the minimum number of eggs, pupa, female flies, male flies, adult emergence from pupa (flies) and period of the pupa. The current study concluded there is a need to evaluate other host plants against these fruit fly species for effective control.     

Signal transduction in lemon seedlings in the hypersensitive response against Alternaria alternata: participation of calmodulin,G-protein and protein kinases

The development of an effective hypersensitive response (HR) in any plant system relies, not only in their gene composition and expression, but also on an effective and rapid signal transduction system. Lemon seedlings induce the phenylpropanoid pathway, which results in the de novo biosynthesis of the phytoalexin scoparone, as part of the hypersensitive response against Alternaria alternata. In order to elucidate some of the signaling elements that participate in the development of HR in lemon seedlings, we used several compounds that are known as activators or inhibitors of signal transduction elements in plants or in animal cells. Lemon seedlings treated either with cholera toxin or with phorbol 12-myristate 13-acetate (PMA), in the absence of A. alternata induced phenylalanine ammonia-lyase (PAL, E. C. 4.3.1.5) and the synthesis of scoparone, suggesting the participation of a G-protein and of a serine/threonine kinase, respectively, in signal transduction. The use of trifluoperazine (TFP), W-7, staurosporine, lavendustin A or 2,5-dihydroximethyl cinnamate (DHMC) prevented PAL induction as well as scoparone biosynthesis in response to the fungal inoculation, thus allowing us to infer the participation of Calmodulin (CaM), of serine/threonine and of tyrosine protein kinases (TPK) for signal transduction in Citrus limon in response to A. alternata.     

Antimicrobial activity of wax and hexane extracts from Citrus spp. peels

Antibacterial and antifungal properties of wax and hexane extracts of Citrus spp. peels were tested using bioautographic and microdilution techniques against three plant pathogenic fungi (Penicillium digitatum, Curvularia sp., and Colletotrichum sp.), two human pathogens (Trichophyton mentagrophytes and Microsporum canis), and two opportunistic bacteria (Escherichia coli and Staphylococcus aureus). Two polymethoxylated flavonoids and a coumarin derivative, were isolated and identified from peel extracts, which presented antimicrobial activity especially against M. canis and T. mentagrophytes: 4',5,6,7,8-pentamethoxyflavone (tangeritin) and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin) from C. reticulata; and 6,7-dimethoxycoumarin (also known as escoparone, scoparone or scoparin) from C. limon.     

Terpene down-regulation in orange reveals the role of fruit aromas in mediating interactions with insect herbivores and pathogens

Plants use volatile terpene compounds as odor cues for communicating with the environment. Fleshy fruits are particularly rich in volatiles that deter herbivores and attract seed dispersal agents. We have investigated how terpenes in citrus fruit peels affect the interaction between the plant, insects, and microorganisms. Because limonene represents up to 97% of the total volatiles in orange (Citrus sinensis) fruit peel, we chose to down-regulate the expression of a limonene synthase gene in orange plants by introducing an antisense construct of this gene. Transgenic fruits showed reduced accumulation of limonene in the peel. When these fruits were challenged with either the fungus Penicillium digitatum or with the bacterium Xanthomonas citri subsp. citri, they showed marked resistance against these pathogens that were unable to infect the peel tissues. Moreover, males of the citrus pest medfly (Ceratitis capitata) were less attracted to low limonene-expressing fruits than to control fruits. These results indicate that limonene accumulation in the peel of citrus fruit appears to be involved in the successful trophic interaction between fruits, insects, and microorganisms. Terpene down-regulation might be a strategy to generate broad-spectrum resistance against pests and pathogens in fleshy fruits from economically important crops. In addition, terpene engineering may be important for studying the basic ecological interactions between fruits, herbivores, and pathogens.     

Participation of the phosphoinositide metabolism in the hypersensitive response of Citrus limon against Alternaria alternata

Lemon seedlings inoculated with Alternaria alternata develop a hypersensitive response (HR) that includes the induction of Phenylalanine ammonia-lyase (PAL, E. C. 4.3.1.5) and the synthesis of scoparone. The signal transduction pathway involved in the development of this response is unknown. We used several inhibitors of the Phosphoinositide (PI) animal system to study a possible role of Inositol-1,4,5-triphosphate (IP3) in the transduction of the fungal conidia signal in Citrus limon. The HR was only partially inhibited by EGTA, suggesting that not only external but internal calcium as well are necessary for a complete development of the HR. In this plant system, Alternaria alternata induced an early accumulation of the second messenger IP3. When lemon seedlings were watered long term with LiCl, an inhibitor of the phosphoinositide cycle, the IP3 production was reduced, and the LiCl-watered plants could neither induce PAL nor synthesize scoparone in response to fungal conidia. Furthermore, neomycin, a Phospholipase C (PLC, E. C. 3.1.4.3) inhibitor, also inhibited PAL induction and scoparone synthesis in response to A. alternata. These results suggest that IP3 could be involved in the signal transduction pathway for the development of the HR of Citrus limon against A. alternata.     

Scoparone O-demethylase assay is not useful to differentiate the effects of model inducers of cytochrome P-450 in rabbit and guinea pig liver

Coumarin derivative, scoparone (6,7-dimethoxycoumarin), is regioselectively O-demethylated into isoscopoletin (I) and scopoletin (S). This oxidation is inversely influenced by cytochrome P-450 inducers in the rat such as 3-methylcholantrene (3-MC) and phenobarbital (PB). The I/S ratio is higher than 1.5 with 3-MC treatment whereas it is lower than 0.5 with PB treatment. With regards to this contrasting effect, it gas been suggested that the I/S ratio should be useful to differemtiate between the effects of these types of inducers. We studied the consequences of in vivo PB and 3-MC treatment on scoparone biotransformation in guinea pig and rabbit. In these two species, at the basal state, scoparone biotransformation was enhanced in comparison to the rat. Moreover, in these untreated animals, two other metabolites were formed. After 3-MC or PB treatment, scoparone metabolism is, in contrast to the rat, inappropriate to differentiate between the P-450 profile of other animals.     

Ecological factors influencing survival and growth of human pathogens on raw fruits and vegetables

Outbreaks of human infections associated with consumption of raw fruits and vegetables have occurred with increased frequency during the past decade. Factors contributing to this increase may include changes in agronomic and processing practices, an increase in per capita consumption of raw or minimally processed fruits and vegetables, increased international trade and distribution, and an increase in the number of immuno-compromised consumers. A general lack of efficacy of sanitizers in removing or killing pathogens on raw fruits and vegetables has been attributed, in part, to their inaccessibility to locations within structures and tissues that may harbor pathogens. Understanding the ecology of pathogens and naturally occurring microorganisms is essential before interventions for elimination or control of growth can be devised.     

Identification and characterization of a hexapeptide with activity against phytopathogenic fungi that cause postharvest decay in fruits

A hexapeptide of amino acid sequence Ac-Arg-Lys-Thr-Trp-Phe-Trp-NH2 was demonstrated to have antimicrobial activity against selected phytopathogenic fungi that cause postharvest decay in fruits. The peptide synthesized with either all D- or all L-amino acids inhibited the in vitro growth of strains of Penicilium italicum, P. digitatum, and Botrytis cinerea, with MICs of 60 to 80 microM and 50% inhibitory concentration (IC50) of 30 to 40 microM. The inhibitory activity of the peptide was both sequence- and fungus-specific since (i) sequence-related peptides lacked activity (including one with five residues identical to the active sequence), (ii) other filamentous fungi (including some that belong to the genus Penicllium) were insensitive to the peptide's antifungal action, and (iii) the peptide did not inhibit the growth of several yeast and bacterial strains assayed. Experiments on P. digitatum identified conidial germination as particularly sensitive to inhibition although mycelial growth was also affected. Our findings suggest that the inhibitory effect is initially driven by the electrostatic interaction of the peptide with fungal components. The antifungal peptide retarded the blue and green mold diseases of citrus fruits and the gray mold of tomato fruits under controlled inoculation conditions, thus providing evidence for the feasibility of using very short peptides in plant protection. This and previous studies with related peptides indicate some degree of peptide amino acid sequence and structure conservation associated with the antimicrobial activity, and suggest a general sequence layout for short antifungal peptides, consisting of one or two positively charged residues combined with aromatic amino acid residues.     

Improving Biocontrol Activity of Pichia guillermondii Against Post-harvest Decay of Oranges in Commercial Packing-houses by Reduced Concentrations of Fungicides

Three commercial tests were conducted in 2000-2001 in two commercial packing-houses (Muravera and Villacidro) located in Sardinia, Italy, to evaluate the efficacy of biological, chemical and integrated treatments against Penicillium digitatum and P. italicum on naturally inoculated orange fruit. Damage caused by the packing-house processing line was also assessed. Treating orange fruits with the yeast Pichia guilliermondii (strain 5A) in the processing line generally led to a significant reduction of post-harvest decay compared to the processed control, while the commercial product Aspire®, based on Candida oleophila , was ineffective in inhibiting the pathogen when applied alone. The integrated application of thiabendazole or imazalil with the biocontrol agents significantly improved the control of fruit decay. Using thiabendazole at concentrations of 0.1 and 1.2 g L -1 , led to similar inhibition of fruit decay in two trials. Both yeasts were equally able to colonize the fruit actively during storage. Passing fruits through the packing line caused a significant increase in fruit decay.     

Differential Induction of Proteins in Orange Flavedo by Biologically Based Elicitors and Challenged byPenicillium digitatumSacc.

The effects of biologically based inducing agents (elicitors) applied singly or in combination to harvested oranges were investigated for enhancing host resistance to green mold. Oranges (Citrus sinensiscv. ‘Valencia’) treated with inducing agents and challenged by the green mold pathogen (Penicillium digitatum) showed a delay in the onset and progression of disease symptoms compared with inoculated fruits not treated with the elicitors. Chitosan (a preparation of ground crab shells), Margosan-O (an oil-based plant-derived product from neem seed) + Aspire (a water dispersible granule containing an antagonistic yeast), Aspire, and chitosan + Aspire reduced fruit decay 38, 41, 42, and 44%, respectively. The inducing agents reduced disease incidence but not disease severity. Application of elicitors followed by inoculation withP. digitatumandP. digitatuminfection alone increased total soluble proteins in the flavedo (the tissue that forms the outer colored rind) twofold relative to the untreated control. The flavedo is an important tissue that is vulnerable to postharvest diseases especially at storage and transport of the harvested crop. No apparent qualitative differences were visualized in protein patterns analyzed by SDS–PAGE of all treatments across all days of incubation. A temporal differential induction of chitinase, β-1,3-glucanase, and peroxidase was demonstrated as a result of elicitor application followed by challenge inoculation withP. digitatum.Induction of these enzymes was corroborated by immunodetection. Lysozyme and a polygalacturonase-inhibiting protein were detected at low activity levels. However, the defensive proteins appeared to be constitutive and slightly induced but did not involve thede novosynthesis of novel proteins.     

Effect of Pattern and Duration of Breastfeeding on the Consumption of Fruits and Vegetables among Preschool Children

Background

The duration and pattern of breastfeeding can influence the consumption of fruits and vegetables in later childhood.

Objective

To investigate the association between pattern and duration of breastfeeding and consumption of fruits and vegetables in children aged between 4 and 7 years.

Methods

We conducted a secondary analysis using data from a former randomized clinical trial with 323 adolescent mothers, their children, and maternal grandmothers, when they cohabited. Information on infant feeding was collected monthly during the first 6 months of life, every two months until the child was 1 year old over and when children were between 4 and 7 years old. The associations between duration of breastfeeding and exclusive breastfeeding and consumption of fruits and vegetables were tested by a logistic regression model.

Results

Approximately 60% and 45% of children consumed fruits and vegetables, respectively, five or more times a week. Consumption of vegetables among 4-7-year-old children was higher in children who were breastfed for 12 months or longer (OR 2.7; 95%CI 1.49–4.93); however, exclusive breastfeeding duration did not have a significant association with consumption of vegetables (OR 1.5; 95%CI 0.70–3.04). There was no association between weekly consumption of fruits and duration of breastfeeding (OR 1.3; 95%CI 0.71–2.30) or exclusive breastfeeding (OR 0.7; 95%CI 0.34–1.44).

Conclusions

Longer duration of breastfeeding was positively associated with consumption of vegetables in children aged 4–7 years; however, there was no association with consumption of fruits. Exclusive breastfeeding duration did not have influence on consumption of fruits or vegetables.     

Changes in Intake of Fruits and Vegetables and Weight Change in United States Men and Women Followed for Up to 24 Years: Analysis from Three Prospective Cohort Studies

BackgroundCurrent dietary guidelines recommend eating a variety of fruits and vegetables. However, based on nutrient composition, some particular fruits and vegetables may be more or less beneficial for maintaining or achieving a healthy weight. We hypothesized that greater consumption of fruits and vegetables with a higher fiber content or lower glycemic load would be more strongly associated with a healthy weight.ConclusionsIncreased consumption of fruits and non-starchy vegetables is inversely associated with weight change, with important differences by type suggesting that other characteristics of these foods influence the magnitude of their association with weight change.     

Quantitative microbial risk assessment models for consumption of raw vegetables irrigated with reclaimed water

Quantitative microbial risk assessment models for estimating the annual risk of enteric virus infection associated with consuming raw vegetables that have been overhead irrigated with nondisinfected secondary treated reclaimed water were constructed. We ran models for several different scenarios of crop type, viral concentration in effluent, and time since last irrigation event. The mean annual risk of infection was always less for cucumber than for broccoli, cabbage, or lettuce. Across the various crops, effluent qualities, and viral decay rates considered, the annual risk of infection ranged from 10(-3) to 10(-1) when reclaimed-water irrigation ceased 1 day before harvest and from 10(-9) to 10(-3) when it ceased 2 weeks before harvest. Two previously published decay coefficients were used to describe the die-off of viruses in the environment. For all combinations of crop type and effluent quality, application of the more aggressive decay coefficient led to annual risks of infection that satisfied the commonly propounded benchmark of < or =10(-4), i.e., one infection or less per 10,000 people per year, providing that 14 days had elapsed since irrigation with reclaimed water. Conversely, this benchmark was not attained for any combination of crop and water quality when this withholding period was 1 day. The lower decay rate conferred markedly less protection, with broccoli and cucumber being the only crops satisfying the 10(-4) standard for all water qualities after a 14-day withholding period. Sensitivity analyses on the models revealed that in nearly all cases, variation in the amount of produce consumed had the most significant effect on the total uncertainty surrounding the estimate of annual infection risk. The models presented cover what would generally be considered to be worst-case scenarios: overhead irrigation and consumption of vegetables raw. Practices such as subsurface, furrow, or drip irrigation and postharvest washing/disinfection and food preparation could substantially lower risks and need to be considered in future models, particularly for developed nations where these extra risk reduction measures are more common.     

Evaluation of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) as a mortality factor of Ceratitis capitata (Diptera: Tephritidae) infesting Citrus species under laboratory and field-cage conditions

Ceratitis capitata (or medfly) is one of the major pests currently affecting fruit crops in northwestern Argentinian Citrus-producing areas. Medfly populations are sustained in large exotic fruits, such as Citrus paradisi, Citrus aurantium and Citrus sinensis, which are known to hinder the activity of almost all native parasitoid species. Therefore, a feasible approach to controlling medfly involves the use of exotic parasitoids such as Diachasmimorpha longicaudata. In this study, the prediction that parasitoid females would be proficient at finding medfly larvae infesting the Citrus species mentioned earlier was tested. Particularly, the variation in fruit species preference by parasitoid females, the efficacy of the parasitoid to kill medfly and the effect of host density on parasitoid performance were determined. Parasitoids were allowed to forage for 8 h on grapefruits and oranges artificially infested with medfly larvae under controlled (laboratory) and uncontrolled (field cage) environmental conditions. Fruit choice and no-choice tests were performed. Results were assessed by comparing the number of female visits to and ovipositor insertions into the fruit, and parasitoid emergence, parasitism and additional host mortality percentages. Parasitoid preference for visiting larger fruits (sour orange and grapefruit) may be related to the increased fruit surface area. Ovipositional activity on fruit was influenced by the variation of the larval host density per unit of fruit surface. The higher parasitism rates recorded from sweet orange would be mainly a result of both increased host density and fruit physical features. Nevertheless, D. longicaudata showed the capacity to parasitise hosts in all Citrus species tested.     

金柚贮藏真菌病害及保鲜技术研究

1998年5月-2000年10月间调查了梅州柚果贮藏期的真菌病害,它们是:①柚果绿霉病(Penicilliumdigitatum),②柚果炭疽病(Collettrichumgloeosporioides),③柚果黑腐病(Alternariacitri),④柚果焦腐病(Diplodianatalensis)和⑤柚果酸腐病(Oosporacitri-aurantii)等5种.从几种安全性高的保鲜剂中筛选出1个混用配方,该配方对柚果贮藏防腐保鲜效果明显,贮藏5个月无病斑果达100%,6个月也只有20%的柚果出现少量病斑,且柚果几项质量指标较好.     

Dietary patterns with fresh fruits and vegetables consumption and quality of sleep among older adults in mainland China

With modern society’s increased pressures, problems arise regarding duration and quality of sleep. Many Chinese seniors report poor quality of sleep. With rapid urbanization, Chinese dietary patterns have shifted dramatically, with vegetables consumption declining rapidly. This research focuses on the associations between fruits and vegetables consumption with basic dietary behaviors and sleeping patterns. Using the 2014 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), multinomial logistic regression models predicted older adults’ (age > = 65) quality and duration of sleep. Predictors included fruits and vegetables consumption, types of cooking oil, staple foods, and meat. The mean age of the study sample was around 85 years. Approximately 56% of respondents consumed fresh vegetables daily. A majority of seniors consumed rice as their staple food. Only 14% of seniors consumed fresh fruits daily. Most seniors consumed meat weekly or more frequently. We found that seniors who consumed fruits and vegetables occasionally had lower odds of reporting good quality of sleep [Fruits: AOR (Adjusted odds ratio) = 0.77; Vegetables: AOR = 0.58] compared with daily consumers. Respondents who reported consuming wheat and half rice-half wheat had higher odds of reporting good quality of sleep (Wheat: AOR = 1.52; Half rice-half wheat: AOR = 1.28), compared with seniors who reported rice as their staple food. Chinese public health practitioners and nutritionists should design dietary plans with more frequent consumption of fruits, vegetables, and wheat to help older adults’ overall health including their sleeping patterns.

     

Phytoalexin Induction as a Factor in the Protection of Capsicum annuum L. Fruits Against Infection by Botrytis cinerea Pers.

Immature Capsicum annuum fruits treated at wound-sites with glucans from the hyphal walls of Glomerella cingulata and incubated for 24 h or longer accumulated levels of capsicannol phytoalexins sufficient to inhibit rot development by Botrytis cinerea. Elicitor application to intact fruits induced the accumulation of relatively low levels of capsicannol compounds but further phytoalexin accumulation in fruits after wound-inoculation with B. cinerea was much more rapid than in untreated fruits and rot development was suppressed. Capsicannol phytoalexins were produced in the live cells of the epidermis and little or no necrosis was associated with quantities produced in intact tissues. Elicitor treatment of intact fruits to protect against rot development by B. cinerea was achieved without the fruits sustaining unsightly damage.