Influence of Bagging on the Development and Quality of Fruits

Investigation on the environmental causes of tomato fruit cracking and its propagation prediction in greenhouse

In this study, Provence tomato variety was chosen for investigating the environmental causes of tomato fruit cracking, cracks characteristics, and their propagation prediction in a greenhouse. Fruit bagging approach was used to alter the temperature and humidity and to create a microclimate around the fruit to induce fruit cracking for testing. Results showed that the fruit cracking rate increased when the environment temperature exceeded 30°C, and the difference between the highest and lowest temperature values in a day was greater than 20°C. The cracking rate was aggravated when the difference between the highest and lowest humidity values in a day was less than 20%. The proportions of top cracking, longitudinal cracking, ring cracking, radial cracking, and combined cracking were 5.4%, 16.1%, 28.3%, 26.8%, and 32.1%, respectively. The fruit shoulder was the most susceptible region to crack, followed by fruit belly and top regions, whereas longer cracks were observed in the fruit belly region indicating a higher propensity to crack propagation in that region. Finally, the measured data were used to validate an extended finite element method developed to effectively predict cracking susceptibility and propagation in tomato fruit with a relative error of 4.68%.

Effects of Different Pre-Harvest Bagging Times on Fruit Quality of Apple

Pre-harvest bagging can improve fruit color and protects against diseases. However, it was discovered that improper bagging times could lead to peel browning in production. Using the Ruixue apple variety as the research model, a study was conducted to compare the external and internal quality of fruits bagged at seven different timings between 50 and 115 days after full bloom (DAFB). Our findings indicate that delaying the bagging time can reduce the occurrence of peel browning in Ruixue apples. Compared to the control, the special bag reduced the browning index by 22.95%. However, the fruit point index of Ruixue fruits increased by 65.05% at 115 DAFB compared to 50 DAFB when bagging was delayed. The chlorophyll content of Ruixue fruits in special bags generally increased and then decreased, with the highest chlorophyll content of Ruixue fruits in special bags at 90 DAFB, which was 26.02 mg·kg-1. When the bagging process was delayed, the soluble solids, total phenols, and flavonoids content in the fruits increased, while the number of control volatiles decreased by 10. After two years of testing, results show that using special fruit bags at 90 DAFB bagging can significantly improve the fruit quality of Ruixue apple.

Factors influencing fruit cracking: an environmental and agronomic perspective

Fruit cracking, a widespread physiological disorder affecting various fruit crops and vegetables, has profound implications for fruit quality and marketability. This mini review delves into the multifaceted factors contributing to fruit cracking and emphasizes the pivotal roles of environmental and agronomic factors in its occurrence. Environmental variables such as temperature, relative humidity, and light exposure are explored as determinants factors influencing fruit cracking susceptibility. Furthermore, the significance of mineral nutrition and plant growth regulators in mitigating fruit cracking risk is elucidated, being calcium deficiency identified as a prominent variable in various fruit species. In recent years, precision farming and monitoring systems have emerged as valuable tools for managing environmental factors and optimizing fruit production. By meticulously tracking parameters such as temperature, humidity, soil moisture, and fruit skin temperature, growers can make informed decisions to prevent or alleviate fruit cracking. In conclusion, effective prevention of fruit cracking necessitates a comprehensive approach that encompasses both environmental and agronomic factors.

Sweet cherry TCP gene family analysis reveals potential functions of PavTCP1, PavTCP2 and PavTCP3 in fruit light responses

BACKGROUND

TCP proteins are plant specific transcription factors that play important roles in plant growth and development. Despite the known significance of these transcription factors in general plant development, their specific role in fruit growth remains largely uncharted. Therefore, this study explores the potential role of TCP transcription factors in the growth and development of sweet cherry fruits.

RESULTS

Thirteen members of the PavTCP family were identified within the sweet cherry plant, with two, PavTCP1 and PavTCP4, found to contain potential target sites for Pav-miR159, Pav-miR139a, and Pav-miR139b-3p. Analyses of cis-acting elements and Arabidopsis homology prediction analyses that the PavTCP family comprises many light-responsive elements. Homologs of PavTCP1 and PavTCP3 in Arabidopsis TCP proteins were found to be crucial to light responses. Shading experiments showed distinct correlation patterns between PavTCP1, 2, and 3 and total anthocyanins, soluble sugars, and soluble solids in sweet cherry fruits. These observations suggest that these genes may contribute significantly to sweet cherry light responses. In particular, PavTCP1 could play a key role, potentially mediated through Pav-miR159, Pav-miR139a, and Pav-miR139b-3p.

CONCLUSION

This study is the first to unveil the potential function of TCP transcription factors in the light responses of sweet cherry fruits, paving the way for future investigations into the role of this transcription factor family in plant fruit development.

Transcriptome and Physiological Analysis Highlight Lignin Metabolism of the Fruit Dots Disordering during Postharvest Cold Storage in 'Danxiahong' Pear

Pear (Pyrus L.) is one of the most important fruits in the world. Fruit dots are an important trait that affects pear quality. Abnormal fruit dots usually reduce the merchantability of pears. In this research, during cold storage, 'Danxiahong' pear fruit exhibited protrudent fruit dots on the peels. Microscopy system measurement showed that fruit dots size and height on the abnormal fruit peel were bigger and higher than the normal ones. Likewise, scanning electron microscopy observations indicated that the abnormal fruit peel, in contrast to the normal pear peel, exhibited an abnormal cell structure and fruit dots. Physiological analysis showed that the lignin content in abnormal fruit peel was significantly higher than in normal fruit peel. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that the top-enriched pathways were mainly associated with lignin synthesis and metabolism. The transcripts of lignin biosynthesis-associated genes were analyzed, and the results showed that the expression of a cascade of structural genes, including PpyPAL, PpyCCR, PpyC3H, PpyC4H, PpyHCT, PpyCAD, PpyLAC, and PpyPOD, was significantly induced in the protrudent peels. Furthermore, the expression of regulatory genes involved in lignin biosynthesis, especially the NAC-MYB-based gene regulatory network, was significantly upregulated in the abnormal peels. Real-time quantitative PCR (RT-qPCR) analysis confirmed the induction of lignin biosynthesis genes. Overall, this research revealed that the abnormal fruit surface was caused by fruit dots disorder during cold storage. This research provides insights into the fine regulation pathways in the prevention of fruit dots protrusion, especially in modulating lignin synthesis and metabolism during postharvest storage.

Metabolome and transcriptome profiling in different bagging pear fruit reveals that PbKCS10 affects the occurrence of superficial scald via regulating the wax formation

Superficial scald is a physiological disorder of fruit, which is easy to occur during long-term cold storage after harvest. Different preharvest bagging treatments (no bagging, polyethylene bagging and non-woven fabric bagging) were used to explore the occurrence mechanism of superficial scald. UHPLC-MS analysis, GC-MS analysis and RNA-seq revealed the influence of the wax of 'Chili' on the occurrence of superficial scald. The wax content and wax components (Lupeol, lup-20(29)-en-3-one, heptacosane, 9-octadecenoic acid, eicosanoic acid, cis-11-eicosenoic acid) were significantly higher in the fruit bagged with non-woven fabric (NWF, with low incidence of superficial scald) than that in fruit bagged with polyethylene (PE, high incidence of superficial scald). Transcriptomics and qRT-PCR data identified a wax synthesis gene, PbKCS10, which exhibited high expression levels in fruit with low of superficial scald. The results of gene function showed that PbKCS10 reduced the occurrence of superficial scald by increasing the wax formation.

Physicochemical properties of lignin nanoparticles from softwood and their potential application in sustainable pre-harvest bagging as transparent UV-shielding films

Technical lignin can be mainly obtained as a waste by-product from pulp industry, and it exhibits unique properties including ultraviolet adsorption, biodegradable, antibacterial, and antioxidant which can be utilized for bioplastic applications. However, common limitations of technical lignin for plastic applications are compatibility mainly due to poor interfacial adhesion, relatively large particle size and impurity. In this study lignin nanoparticles from softwood (S-LNPs) were successfully produced through a continuous-green-scalable antisolvent precipitation and the suitability of S-LNPs for fabrication of bio-composite polybutylene succinate (PBS) films using conventional blown film extrusion was examined. The attained S-LNPs showed lower ash content, higher phenolic content and higher lignin content compared to pristine softwood kraft lignin (S-lignin). Rheological property including shear viscosity and melt-flow index was determined. The obtained PBS/S-LNP composite films showed improved tensile modulus, higher water vapor transmission rate and excellent UV-shielding ability compared to neat PBS and PBS/S-lignin films. Accelerated weathering testing was conducted to replicate outdoor conditions. Degradation indices including carbonyl, vinyl and hydroxyl of the weathered PBS/lignin composites were evaluated for photo-oxidative stability. The S-LNPs as multifunctional bio-additives in biodegradable composite film exhibited superior performances of transparency, UV-absorption and stiffness with high photo-oxidative stability suitable for outdoor applications.

LhANS-rr1, LhDFR, and LhMYB114 Regulate Anthocyanin Biosynthesis in Flower Buds of Lilium ‘Siberia’

The bulb formation of Lilium is affected by many physiological and biochemical phenomena, including flower bud differentiation, starch and sucrose accumulation, photoperiod, carbon fixation, plant hormone transduction, etc. The transcriptome analysis of flower buds of Lilium hybrid ‘Siberia’ at different maturity stages showed that floral bud formation is associated with the accumulation of anthocyanins. The results of HPLC-MS showed that cyanidin is the major anthocyanin found in Lilium ‘Siberia’. Transcriptome KEGG enrichment analysis and qRT-PCR validation showed that two genes related to flavonoid biosynthesis (LhANS-rr1 and LhDFR) were significantly up-regulated. The functional analysis of differential genes revealed that LhMYB114 was directly related to anthocyanin accumulation among 19 MYB transcription factors. Furthermore, the qRT-PCR results suggested that their expression patterns were very similar at different developmental stages of the lily bulbs. Virus-induced gene silencing (VIGS) revealed that down-regulation of LhANS-rr1, LhDFR, and LhMYB114 could directly lead to a decrease in anthocyanin accumulation, turning the purple phenotype into a white color. Moreover, this is the first report to reveal that LhMYB114 can regulate anthocyanin accumulation at the mature stage of lily bulbs. The accumulation of anthocyanins is an important sign of lily maturity. Therefore, these findings have laid a solid theoretical foundation for further discussion on lily bulb development in the future.

Blue Light Simultaneously Induces Peel Anthocyanin Biosynthesis and Flesh Carotenoid/Sucrose Biosynthesis in Mango Fruit

Previous studies focused on the effects of light on fruit appearance, especially the peel color. However, the effect of light on fruit internal quality and the underlying mechanisms are unclear. In this study, we analyzed the effects of blue light on the appearance and internal quality of mango fruit (Mangifera indica L.). Blue light simultaneously induced peel anthocyanin and flesh sucrose/carotenoid biosynthesis in mango fruit. Analyses of co-expression networks and gene expression trends in mango fruit peel and flesh identified candidate genes, including transcription factor genes, involved in blue light-regulated anthocyanin, carotenoid, and sucrose biosynthesis pathways. Key blue light signaling-related genes (MiCRY and MiHY5) and blue light-triggered phytohormones were involved in these pathways. Additionally, there were common and tissue-specific pathways for the blue light-promoted accumulation of anthocyanins, carotenoids, and sucrose. Our results provide new insights into the regulatory effects of light on the appearance and internal quality of mango fruit.

Fruit bagging reduces the postharvest decay and alters the diversity of fruit surface fungal community in 'Yali' pear

Background

Fruit bagging is an effective technique for fruit protection in the orchard management. Bagging can create a micro-environment for fruit growth and affect fruit quality during storage, in which the diversity of microorganisms may play an important role. Therefore, various methods including biochemistry, analytical chemistry, and bioinformatics methods were used to reveal the influences of fruit bagging on postharvest fruit quality, physiological characters, decay and surface fungal community of ‘Yali’ pear fruit were investigated in this study.

Results

Fruit bagging significantly decreased the postharvest decay after 15 days of ambient storage. There were no significant differences in fruit firmness, titratable acid and ethylene production rate between the fruit-bagging and non-bagging group after 15 days of storage, while the soluble solids contents (SSC) and respiration rate in non-bagging fruit was significantly higher than that in fruit-bagging after 15 days of storage. Furthermore, the surface microbes of pear were collected and determined by the new generation sequencing technology. The alpha diversity of fungi in non-bagging fruit decreased significantly after 15 days of storage, while there were no significant changes in bagging fruit. Ascomycota and Basidiomycota were the two major phyla detected in the bagging fruit, and the dominant fungal genera were Alternaria (23.7%), Mycosphaerella (17.25%), Vishniacozyma (16.14%), and Aureobasidium (10.51%) after 15 days of storage. For the non-bagging pear, Ascomycota was the only phylum detected, and the dominant genera was Pichia (83.32%) after 15 days of storage. The abundance of Pichia may be regarded as the biomarker to indicate the degree of fruit decay.

Conclusions

This study showed that fruit bagging could significantly reduce postharvest fruit decay and respiration rate of ‘Yali’ pear. Significant differences were found in fungal composition between bagging and non-bagging pear after storage for 0 or 15 days. Fruit bagging maintained the diversity of fungi on the fruit surface, increased the abundance of non-pathogenic fungi, and even antagonistic fungi such as Aureobasidium, Vishniacozyma, and Mycosphaerella. A reduction in the abundance of pathogenic fungi and incidence of postharvest decay during the storage of ‘Yali’ pear were also recorded. In conclusion, fruit-bagging changed the fungal diversity on fruit surface of ‘Yali’ pear, which had significant effect on reducing postharvest fruit decay, and thus prolong the storage period of ‘Yali’ pears. The future thrust of this study will focus on the isolation of fungi or bacteria from pear fruit surface and identify their roles in causing fruit decay and changing fruit quality during storage.

Heat stress mitigation in tomato (Solanum lycopersicum L.) through foliar application of gibberellic acid

Phytohormones mediate physiological, morphological, and enzymatic responses and are important regulators of plant growth and development at different stages. Even though temperature is one of the most important abiotic stressors for plant development and production, a spike in the temperature may have disastrous repercussions for crop performance. Physiology and growth of two tomato genotypes ('Ahmar' and 'Roma') were studied in two growth chambers (25 and 45 °C) when gibberellic acid (GA₃) was applied exogenously. After the 45 days of planting, tomato plants were sprayed with GA₃ at concentrations of 25, 50, 75, and 100 mg L⁻¹, whereas untreated plants were kept as control. Under both temperature conditions, shoot and root biomass was greatest in 'Roma' plants receiving 75 mg L⁻¹ GA₃, followed by 50 mg L⁻¹ GA₃. Maximum CO₂ index, photosynthetic rate, transpiration rate, and greenness index were recorded in 'Roma' plants cultivated at 25 °C, demonstrating good effects of GA₃ on tomato physiology. Likewise, GA₃ enhanced the proline, nitrogen, phosphorus, and potassium levels in the leaves of both genotypes at both temperatures. Foliar-sprayed GA₃ up to 100 mg L⁻¹ alleviated the oxidative stress, as inferred from the lower concentrations of MDA and H₂O_2, and boosted the activities of superoxide dismutase, peroxidase, catalase. The difference between control and GA₃-treated heat-stressed plants suggests that GA₃ may have a function in mitigating heat stress. Overall, our findings indicate that 75 mg L⁻¹ of GA₃ is the optimal dosage to reduce heat stress in tomatoes and improve their morphological, physiological, and biochemical characteristics.

Influence of fruit bagging technique on the morphometric and biochemical characteristics of two pomegranate varieties (Punica granatum L.)

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The bagging technique shown influence in the size and shape of the pomegranate fruits.

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TSS, MI, glucose, α punicalagin, α + β punicalagin, and ellagic acid was affected by bagging.

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pH, TA, ABTS, DPPH, FRAP, TP, fructose, organic acids, β punicalagin and anthocyanins were not influenced.

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It can be said that bagging can improve fruit quality by reducing external damage.

The pomegranate tree is cultivated and its fruits consumed since ancient times. This tree is typical of the Mediterranean climate, with high thermal demands to mature properly. The main objective of this work was to study the influence of the fruit bagging technique on the morphometric and biochemical characteristics of the pomegranate fruits of two new varieties that are currently cultivated in the Southeast of Spain. The results indicated that the fruit bagging presented a significant effect on the weight, equatorial diameter, height and shape of the fruit, however, it did not show any influence on the peel thickness. No significant differences have been observed in the number of healthy fruits with and without bagging, however, the number of cracked fruits with Cryptoblabes gnidiella damage was higher for the non-bagged fruits. The fruit bagging presented a significant effect on the total soluble solids, maturity index, glucose, α-punicalagin, α + β-punicalagin and ellagic acid, but it did not show influence on pH, acidity, ABTS, DPPH, FRAP, total phenols, fructose, citric, malic, and quinic acid, β-punicalagin and anthocyanins. The internal fruit color was not affected by the bagging, although it did affect the external color of the fruit, and unevenly depending on the variety. Based on the results, it can be said that bagging can improve the quality of the fruit by reducing damage from pests and pathophysiology, and this benefit compensates or even exceeds the negative effects of bagging on peel color.

Effect of Paper and Aluminum Bagging on Fruit Quality of Loquat (Eriobotrya japonica Lindl.)

Bagging regulates the fruit microenvironment and improves the quality and market value of fruits. It is a safe and ecofriendly technique to protect fruits from insect/pest infestation and multiple biotic and abiotic stresses. In the current study, the influence of fruit bagging was evaluated on the development and quality of loquat fruits. Fruits from a healthy loquat orchard (Cv. Zaozhong No.6), located in Fujian, China, were enveloped in paper (T1), aluminum (T2), and aluminum-polyethylene bags (T3), while unbagged fruits were maintained as control (T0). In general, fruit bagging improved fruit quality in terms of fruit physiological and biochemical attributes and protected fruits from physical damage. In particular, aluminum-polyethylene bagging enhanced fruit weight, length, and width by 1.37-, 1.18-, and 1.13-fold, respectively. Loquat fruits bagged with paper bags exhibited the maximum soluble sugar and lowest titratable acid content. Fruits treated with paper and aluminum-ethylene bags showed twofold higher sugar-acid ratio as compared to control. Aluminum-polyethylene bagging caused 66.67%, 55.56%, and 33.33% reductions in skin burn, fruit rotting, and black spot of loquat. The fruits bagged in aluminum and aluminum-polyethylene did not show insect or bird damage, while unbagged fruits had 14.70% and 17.65% insect and bird damage, respectively. Overall, the results suggest that paper, aluminum, and aluminum-polyethylene bagging improved fruit health by 75%, 131%, and 144%, respectively, as compared to control. To delineate bagging type-dependent effects, principal component analysis was performed. Paper bagging was positively correlated with fruit firmness, rotting, soluble sugars, sugar-acid ratio, and proline content. Aluminum bagging was highly associated with improvements in titratable acids, cystine, and methionine. Aluminum-polyethylene bags were correlated with fruit weight, size, peel thickness, edible rate, and certain amino acids.

Increasing the performance of Passion fruit (Passiflora edulis) seedlings by LED light regimes

Due to progress in the industrial development of light-emitting diodes (LEDs), much work has been dedicated to understanding the reaction of plants to these light sources in recent years. In this study, the effect of different LED-based light regimes on growth and performance of passion fruit (Passiflora edulis) seedlings was investigated. Combinations of different light irradiances (50, 100, and 200 µmol m⁻² s⁻¹), quality (red, green, and blue light-emitting LEDs), and photoperiods (10 h/14 h, 12 h/12 h and 14 h/10 h light/dark cycles) were used to investigate the photosynthetic pigment contents, antioxidants and growth traits of passion fruit seedlings in comparison to the same treatment white fluorescent light. Light irradiance of 100 µmol m⁻² s⁻¹ of a 30% red/70% blue LED light combination and 12 h/12 h light/dark cycles showed the best results for plant height, stem diameter, number of leaves, internode distance, and fresh/dry shoot/root weights. 14 h/10 h light/dark cycles with the same LED light combination promoted antioxidant enzyme activities and the accumulation of phenols and flavonoids. In contrast, lower light irradiance (50 µmol m⁻² s⁻¹) had negative effects on most of the parameters. We conclude that passion fruit seedlings' optimal performance and biomass production requires long and high light irradiances with a high blue light portion.

Analysis of Light-Independent Anthocyanin Accumulation in Mango (Mangifera indica L.)

Light dependent anthocyanin accumulation contributes to the red pigmentation of the fruit skin of mango (Mangifera indica L.). Light-independent pigmentation has also been reported, but remains poorly characterized. In this study, the pigmentation patterns in the skin of two red mango cultivars, ‘Ruby’ and ‘Sensation’, were evaluated. Metabolomic profiling revealed that quercetin-3-O-glucoside, cyanidin-3-O-galactoside, procyanidin B1, and procyanidin B3 are the predominant flavonoid compounds in the skin of ‘Ruby’ and ‘Sensation’ fruit. Young fruit skin mainly accumulates flavonol and proanthocyanidin, while anthocyanin is mainly accumulated in the skin of mature fruit. Bagging treatment inhibited the biosynthesis of flovonol and anthocyanin, but promoted the accumulation of proanthocyanidin. Compared with ‘Sensation’, matured ‘Ruby’ fruit skin showed light red pigmentation at 120 days after full bloom (DAFB), showing a light-independent anthocyanin accumulation pattern. However, the increase of anthocyanin concentration, and the expression of key anthocyanin structural and regulatory genes MiUFGT1, MiUFGT3, and MiMYB1 in the skin of bagged ‘Ruby’ fruit versus ‘Sensation’ at 120 DAFB was very limited. There was no mutation in the crucial elements of MiMYB1 promoter between ‘Ruby’ and ‘Sensation’. We hypothesize that the light-independent anthocyanin accumulation in the skin of mature ‘Ruby’ fruit is regulated by plant hormones, and that ‘Ruby’ can be used for breeding of new more easily pigmented red mango cultivars.

Flavonoids Accumulation in Fruit Peel and Expression Profiling of Related Genes in Purple (Passiflora edulis f. edulis) and Yellow (Passiflora edulis f. flavicarpa) Passion Fruits

Flavonoids play a key role as a secondary antioxidant defense system against different biotic and abiotic stresses, and also act as coloring compounds in various fruiting plants. In this study, fruit samples of purple (Passiflora edulis f. edulis) and yellow (Passiflora edulis f. flavicarpa) passion fruit were collected at five developmental stages (i.e., fruitlet, green, veraison, maturation, and ripening stage) from an orchard located at Nanping, Fujian, China. The contents of flavonoid, anthocyanin, proanthocyanin, and their metabolites were determined using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS), activities of key enzymes involved in flavonoid metabolism were measured, and expression profiling of related genes was done using quantitative real-time PCR (qRT-PCR). The results revealed that total flavonoids, anthocyanins, and procyanidins were found to be increased in the fruit peel of both cultivars with fruit maturity. Total flavonoids, anthocyanins, procyanidins, flavonoid metabolites (i.e., rutin, luteolin, and quercetin), and anthocyanin metabolites (i.e., cyanidin-3-O-glucoside chloride, peonidin-3-O-glucoside, and pelargonidin-3-O-glucoside) were found abundant in the peel of purple passion fruit, as compared to yellow passion fruit. Principle component analysis showed that the enzymes, i.e., C4H, 4CL, UFGT, and GST were maybe involved in the regulation of flavonoids metabolism in the peel of passion fruit cultivars. Meanwhile, PePAL4, Pe4CL2,3, PeCHS2, and PeGST7 may play an important role in flavonoid metabolism in fruit peel of the passion fruit. This study provides new insights for future elucidation of key mechanisms regulating flavonoids biosynthesis in passion fruit.

Light Intensity Alters the Behavior of Monilinia spp. in vitro and the Disease Development on Stone Fruit-Pathogen Interaction

The development of brown rot caused by the necrotrophic fungi Monilinia spp. in stone fruit under field and postharvest conditions depends, among others, on environmental factors. The effect of temperature and humidity are well studied but there is little information on the role of light in disease development. Herein, we studied the effect of two lighting treatments and a control condition (darkness) on: (i) several growth parameters of two Monilinia spp. (M. laxa and M. fructicola) grown in vitro and (ii) the light effect in their capacity to rot the fruit (nectarines) when exposed to the different lighting treatments. We also assessed the effect of such abiotic factors in the development of the disease on inoculated nectarines during postharvest storage. Evaluations also included testing the effect of fruit bagging on disease development as well as on ethylene production. Under in vitro conditions, lighting treatments altered colony morphology and conidiation of M. laxa but this effect was less acute in M. fructicola. Such light-induced changes under in vitro development also altered the capacity of M. laxa and M. fructicola to infect nectarines, with M. laxa becoming less virulent. The performance of Monilinia spp. exposed to treatments was also determined in vivo by inoculating four bagged or unbagged nectarine cultivars, indicating an impaired disease progression. Incidence and lesion diameter of fruit exposed to the different lighting treatments during postharvest showed that the effect of the light was intrinsic to the nectarine cultivar but also Monilinia spp. dependent. While lighting treatments reduced M. laxa incidence, they enhanced M. fructicola development. Preharvest conditions such as fruit bagging also impaired the ethylene production of inoculated fruit, which was mainly altered by M. laxa and M. fructicola, while the bag and light effects were meaningless. Thus, we provide several indications of how lighting treatments significantly alter Monilinia spp. behavior both in vitro and during the interaction with stone fruit. This study highlights the importance of modulating the lighting environment as a potential strategy to minimize brown rot development on stone fruit and to extent the shelf-life period of fruit in postharvest, market, and consumer's house.

Transcriptome data-based identification of candidate genes involved in metabolism and accumulation of soluble sugars during fruit development in 'Huangguan' plum

Fruit sweetness being an important factor of organoleptic quality directly affects the consumers' preferences for fresh fruit consumption, and is influenced by the composition and quantity of sugars. In this study, four soluble sugars (sucrose, fructose, glucose, and sorbitol) were identified and quantified in plum fruits cv. 'Huangguan' at four different maturity stages (fruitlet, green, veraison, and mature stage). The results revealed that sucrose and glucose are major soluble sugar components at the fruitlet and mature stages, respectively. RNA-Seq analysis was carried out and 6,778 differentially expressed genes (DEGs) were identified, including 121 genes involved in sugar metabolism. Furthermore, a total of 39 transcripts of 8 gene families encoding key enzymes related to the metabolism and accumulation of soluble sugars were separately identified. ERD6L (gene 103322904) was involved in keeping a balance of glucose between the inside and outside of vacuole. SS (gene 103333990) and SDH (gene 103335104) regulated the accumulation of fructose at the green stage. SDH (gene 103335104) controlled the degradation of sorbitol at the green stage. SS (gene 103333990) and PFK (gene 103333391) regulated the degradation of sucrose at the early stages of fruit development. Moreover, NINV (gene 103331108) regulated the accumulation of total sugar in plum. Genes 103321334 and 103335689 were important bZIP transcription factors that regulate the accumulation of glucose and fructose in fruits. Twelve DEGs were selected and validated to observe the relative accuracy of transcriptome sequencing data using qRT-PCR. Gene expression patterns were consistent between qRT-PCR and RNA-Seq data, indicating the reliability of RNA-Seq data. PRACTICAL APPLICATIONS: The results of this study provided new insights into comprehensive understanding of the genetic control of sugar metabolism and accumulation in plum fruits.

Changes in the Content of Organic Acids and Expression Analysis of Citric Acid Accumulation-Related Genes during Fruit Development of Yellow (Passiflora edulis f. flavicarpa) and Purple (Passiflora edulis f. edulis) Passion Fruits

Organic acids are key components that determine the taste and flavor of fruits and play a vital role in maintaining fruit quality and nutritive value. In this study, the fruits of two cultivars of passion fruit Yellow (Passiflora edulis f. flavicarpa) and purple (Passiflora edulis f. edulis) were harvested at five different developmental stages (i.e., fruitlet, green, veraison, near-mature and mature stage) from an orchard located in subtropical region of Fujian Province, China. The contents of six organic acids were quantified using ultra-performance liquid chromatography (UPLC), activities of citric acid related enzymes were determined, and expression levels of genes involved in citric acid metabolism were measured by quantitative real-time PCR (qRT-PCR). The results revealed that citric acid was the predominant organic acid in both cultivars during fruit development. The highest citric acid contents were observed in both cultivars at green stage, which were reduced with fruit maturity. Correlation analysis showed that citrate synthase (CS), cytosolic aconitase (Cyt-ACO) and cytosolic isocitrate dehydrogenase (Cyt-IDH) may be involved in regulating citric acid biosynthesis. Meanwhile, the PeCS2, PeACO4, PeACO5 and PeIDH1 genes may play an important role in regulating the accumulation of citric acid. This study provides new insights for future elucidation of key mechanisms regulating organic acid biosynthesis in passion fruit.

Influence of Pre-Harvest Bagging on the Incidence of Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) and Fruit Quality in Mango

Simple Summary

The white mango scale Aulacaspis tubercularis is an invasive pest that causes important damage to mango crops in Southern Spain. The use of integrated management strategies (cultural, biological, and chemical control) is recommended for its effective and sustainable management. Among cultural control measures, fruit bagging technology is being widely used in some mango production regions prior to harvest to protect fruit from diseases, pests, and mechanical damage. However, despite the proven efficacy of bagging, its usefulness has still not been proved to control A. tubercularis infestations on mango fruits. In this study, we evaluated not only the mango bagging efficacy on A. tubercularis control but also its effects on the development and quality of bagged fruits. We tested two commercial types of bags (a yellow satin paper bag and a white muslin cloth bag) commonly used to cover several other fruits. Both bags were effective in reducing the pest incidence and damage caused by A. tubercularis when mango fruits were bagged before the scales migrated to them. Our findings indicate that the use of bags for the pre-harvest protection of mango fruits is feasible, and it may improve their development (weight and size) and quality (color and soluble solids).

Abstract

Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) is the main pest of mango, Mangifera indica L., in Spain, causing significant economic losses by aesthetic damage that reduce the commercial value of fruit. Bagging fruit with two commercial bags (a yellow satin paper and a white muslin cloth bag) was evaluated for control of A. tubercularis in two organic mango orchards during the 2020 cropping season in pursuit of the development of a mango IPM program to produce pest-free and residue-free fruits. Results from fruit damage evaluations at harvest showed that bagging significantly reduced pest incidence and fruit damage compared with non-bagged plots. Of the two bags evaluated, white muslin cloth bag provided higher levels of fruit protection from A. tubercularis damage, reducing the non-commercial fruit percentage by up to 93.42%. Fruit quality assessment indicated that weight and size of bagged fruit were significantly higher than the non-bagged. Paper-bagged mangoes showed higher whiteness and yellowness compared to the other treatments. Soluble solids content (ºBrix) was higher in paper-bagged fruit than all other treatment plots. The results from this study indicate that pre-harvest fruit bagging is effective at controlling A. tubercularis and should be integrated into an IPM program for Spanish mango production.