Affect Fruit Quality Research Articles

Postharvest application of gamma irradiation affects fruit quality and antioxidant enzymes activities of ‘kinnow’ mandarin fruits during cold storage

Food safety with maintained fruit quality is an important challenge for postharvest industry of citrus fruits. The present study was designed to check the effects of gamma irradiation on postharvest fruit quality of ‘Kinnow’ mandarin stored at 5 ± 1 °C and 90 ± 5% Relative Humidity. In the first experiment, fruits were exposed to different doses of gamma radiation (100-500 Gy), while after analyzing the results of first experiment, in the second experiment fruits were treated with 500, 600, 800 and 1000 Gy of gamma radiation. It was observed that higher doses of gamma irradiation exhibited lower weight loss and disease incidence as well as inhibiting the increase of soluble solid content (SSC) and retained higher titratable acidity (TA) and lower SSC: TA ratio. After 90 days of storage, maximum levels ascorbic acid, total phenolic contents and total antioxidants along with catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activities were recorded higher in fruits treated with 800 Gy. These fruit also exhibited higher score of taste, aroma and texture during storage. Overall results suggest that pre-storage treatment of 800 Gy is the most effective treatment and have potential application for quality management of ‘Kinnow’ mandarin under long term cold storage.

Evaluation of a novel water-soluble decanoic acid formulation as a fruit sanitizer

Fruits irrigated with contaminated water can transmit various pathogens. High sugar content in fruits such as black cherry (BC) fruit encourages microbial proliferation. A novel water-soluble decanoic acid (WSDA) was evaluated as a fruit sanitizer and compared with other traditional fruit sanitizers such as ethanol, bleach, or dishwasher surfactants. WSDA sanitizer killed yeasts, molds and bacteria including E. coli microbes effectively as other sanitizers with (4 log cycle reduction) of microbial load. Furthermore, the bacterial sanitization mechanism i.e. bactericidal or bacteriostatic was evaluated for alcohol, bleaching and WASDA solutions. E. coli was selected as the model pathogen used for such comparison. Results indicated that the mechanism of action for the three sanitizer solutions against E. coli was bactericidal. The problem with most used fruit sanitizers is their negative influence on fruit quality in terms of physical, mechanical and taste properties. In addition, some led to toxicological and ecological concerns. Thus, studies were conducted to explore the changes in the exocarp cell structure of BC fruit upon exposure to WSDA and other sanitizers using microscopic investigation. WSDA could have a very mild or gentle effect on the BC fruit cells compared to other sanitizers. Alcohol, bleaching and dishwasher surfactant changed the cellular structures and the intercellular spaces. Sanitizers may also affect fruit swelling. WSDA showed an increase in percent weight gain but it was significantly (p < 0.05) much lower than dishwasher surfactant and bleaching solution. BC Fruit flesh firmness and hardness were investigated upon exposure to different sanitizer solutions. BC fruit treated with WSDA showed the highest firmness values. Some liquid sanitizers could affect fruit quality in terms of fruit taste. Sensory evaluation in terms of the sanitizer's smell, texture and hedonic of BC fruit after soaking in different sanitizers was carried out. All sensory parameters of BC fruit soaked with WSDA were similar with insignificant differences (p > 0.05) compared to BC fruit soaked in tap water. However, the sensory parameters were significantly different (p < 0.05) when compared with alcohol, bleach and dishwasher surfactant. This ensures that WSDA was superior to other evaluated sanitizers in terms of physical, mechanical and fruit quality.

Relationship between crop load and fruit quality in low-chill peaches and nectarines

ABSTRACT Fruits from low-chill peach and nectarine cultivars have lower quality in comparison with traditional varieties. One of the factors that most affect both fruit quality and fruit yield is the crop load (CL). The objective of the present work was to evaluate the relationship between CL and the external and internal fruit quality of low-chill peaches in a temperate-subtropical transition zone of the central-east region of Santa Fe province (Argentina). Fruit diameter (mm), total soluble solids (°Brix), titratable acidity (%), juiciness (%), skin red over-colour (%) and the Commission Internationale de l'Elcairage (CIE) colour parameters, and fruit yield efficiency (kg cm−2 trunk cross-sectional area; TCSA) were evaluated in nine low-chill peach cultivars under three CL treatments: 1.0 (low), 1.5 (medium) and 2.0 (high) fruit cm−2 TCSA. Increasing from low to medium CL did not affect the internal or external fruit quality attributes of any of the nine low-chill cultivars studied but increased fruit yield from 20% to 44% according to the genotype. In some cultivars, such as ‘Don Agustín’ and ‘Lara’, it was possible to increase the CL to 2 fruit cm−2 TCSA without affecting fruit quality.

Leipothrix argutae (Acari: Eriophyidae) infesting kiwi fruit trees in Jilin province, Northeastern China

Eriophyoid mites are herbivorous mites of a worldwide distribution. The genus Leipothrix (Eriophyidae) was established by Keifer (1966) and currently consisted of 53 species (including two species unpublished). This genus is characterized by (1) the absence of femoral setae bv from both legs and (2) the distinctive form of dorsal palp genual setae d, which is moderately long and bifurcate, with its branch being minute or very minute (sometimes seen as a sharp bend in the seta). Most Leipothrix spp. cause no damage and are vagrant on the leaf surface. However, some of them caused russeting and drying of the leaves when the mites were in high density. During field surveys in Zuojia Experimental Plot in Jilin Province, China, we collected two sympatric morphs of Leipothrix species from the hardy kiwi, Actinidia arguta (Siebold &amp; Zucc.) Planch. ex Miq. (Actinidiaceae), a cultivated vine. The mites were later described as L. argutae Han, Wang &amp; Ai, 2020, which is a deuterogynous species (Han et al. 2020). These mites were found with large rust on the surfaces of leaves and fruits of the host plant. Local people wrongly attributed these symptoms to a kind of plant disease. Sometimes L. argutae is also confused with Phyllocoptruta oleivora (Ashmead), which also causes rust in Citrus sp. and other related plant species. This is the first record of Leipothrix species on a species of Actinidiaceae, and also a new record of an eriophyoid mite causing serious symptoms and affecting fruit quality in kiwi fruits. &#x0D;

Unraveling correlations between calcium deficiency and spongy tissue in mango fruit flesh

Spongy tissue, as one of internal flesh breakdown in mango fruits, is correlated with calcium (Ca) deficiency, and adversely affects fruit quality and yield worldwide. However, the underlying mechanism causing spongy tissue remains unknown. Here, we explored the effects of Ca deficiency on spongy tissue in a susceptible cultivar, ‘Keitt’, at the physiological and molecular levels. Nutrient analysis showed that flesh with spongy tissue had lower Ca content and higher N/Ca, K/Ca and Mg/Ca rations than healthy fruit flesh. Ca accumulation in the cell wall, especially in chelator-soluble pectin, was elevated due to increased pectin content, lower levels of pectin methylesterification, and increased pectin methylesterase (PME) activity. During spongy tissue development, levels of Ca oxalate (CaOx) and oxalic acid both increased, whereas soluble Ca content decreased in the flesh. Transcriptomic analysis of healthy flesh and flesh with spongy tissue revealed 2054 up-regulated and 996 down-regulated genes. Gene ontology term analysis showed that the up-regulated genes were mainly enriched in functions related to the transmembrane transporter activity, calcium ion binding, and the cell wall. Importantly, up-regulated genes in spongy tissue included five glucuronate 4-epimerase (GAE) genes and two galactosyltransferase (GALT) genes, which involved in pectin synthesis; four PME genes which control pectin demethylesterification; and eight autoinhibited calcium-transporting ATPase (ACA) genes and two vacuole H+/Ca2+ exchanger (CAX) genes which contribute to Ca influx in the vacuole. Our findings illustrate a mechanism by which Ca deficiency leads to spongy tissue, which will contribute to efforts to control this physiological disorder.

Fruit Characteristics of Citrus Trees Grown under Different Soil Cu Levels.

The effects of the increased soil copper (Cu) on fruit quality due to the overuse of Cu agents have been a hot social issue. Seven representative citrus orchards in Guangxi province, China, were investigated to explore the fruit quality characteristics under different soil Cu levels and the relationship between soil-tree Cu and fruit quality. These results showed that pericarp color a value, titratable acid (TA), and vitamin C (Vc) were higher by 90.0, 166.6, and 22.4% in high Cu orchards and by 50.5, 204.2, and 55.3% in excess Cu orchards, compared with optimum Cu orchards. However, the ratio of total soluble solids (TSS)/TA was lower by 68.7% in high Cu orchards and by 61.6% in excess Cu orchards. With the increase of soil Cu concentrations, pericarp color a value and Vc were improved, TA with a trend of rising first then falling, and TSS/TA with a trend of falling first then rising were recorded. As fruit Cu increased, pericarp color a value and TSS reduced and as leaf Cu increased, TSS/TA decreased while Vc was improved. Moreover, a rise in soil Cu enhanced leaf Cu accumulation, and a rise in leaf Cu improved fruit Cu accumulation. Fruit Cu accumulation reduced fruit quality by direct effects, leaf Cu improved fruit quality by direct and indirect effects. Soil Cu affected fruit quality by indirect effects by regulating leaf Cu and fruit Cu. Therefore, reasonable regulation and control of soil Cu concentrations can effectively increase pericarp color, sugar, and acid accumulation in citrus fruit.

Underlying mechanism of menthol on controlling postharvest citrus sour rot caused by Geotrichum citri-aurantii

Sour rot, caused by Geotrichum citri-aurantii, has affected fruit quality and caused severe economic losses. Menthol is widely applied to medicine and food industries due to its antiseptic and antimicrobial effects, whereas its application in postharvest fruit management is rarely reported. The present study investigated the antifungal activity of menthol and its underlying mechanism involved. The in vitro experiments showed that the minimum inhibitory concentration (MIC) of menthol was 6.4 mmol L-1. Menthol induced the formation and accumulation of reactive oxygen species (ROS) in G. citri-aurantii and triggered severe membrane lipid peroxidation, resulting in the destruction of plasma membrane integrity. The activity of extracellular alkaline phosphatase (AKP) was increased after menthol treatment. Otherwise, the decrease of blue fluorescence in the cell wall and the change of cell wall morphology were also observed, indicating that the cell wall structure was disrupted. Notably, in vivo, the disease incidence of citrus fruit decreased by 43% after the application of 128 mmol L-1 menthol. Furthermore, menthol treatment maintained the quality of citrus fruit and enhanced defense-related enzyme activities in citrus. To further explore the potential pathogenicity of G. citri-aurantii, we de novo assembled the genome of G. citri-aurantii G50 based on Illumina NovaSeq PE150 and PacBio Sequel. The revised genome size was 25.41 Mb, assembled onto 27 scaffolds with a total length of 27,548,716 bp, 38.49% GC content and 4181 protein-coding genes. Herein, we identified four CWI-MAPK-related genes (GciPKC1, GciBCK1, GciMKK1 and GciSLT2). The expressions of these genes were down-regulated after menthol treatment, influencing on downstream chitin and glucan synthesis. Collectively, these results demonstrated that menthol might be beneficial as a potential alternative for decay management of citrus sour rot. Our research provided new perspectives for postharvest disease control and management control of this pathogen and elucidated its pathogenic mechanism.

Abundance and Population Dynamics of the Key Insect Pests and Agronomic Traits of Tomato (Solanum lycopersicon L.) Varieties under Different Planting Densities as a Sustainable Pest Control Method

In Saudi Arabia, the tomato is susceptible to a wide range of insect pests that could destroy this valuable vegetable crop, cause yield losses, and affect fruit quality and quantity. Insecticides are widely applied to protect tomatoes and control pests that develop a resistance to pesticides, but these affect human health and have a negative impact on the environment. The application of Good Agriculture Practices (GAP) is a worthwhile sustainable alternative for controlling insect pests in tomato fields. To investigate the population dynamics of the major pests affecting tomato growth and yield, two commercial varieties (Areenez F1 and Tala F1) were cultivated at three plant spacings (30 × 50 cm, 60 × 50 cm, and 90 × 50 cm) under the conditions of the desert climate. The experiments were conducted in the field in 2020 and 2021 and were laid out in a Randomized Complete Block Design (RCBD) with each treatment repeated for 4 times. A total of 14 major insect pests including Empoasca fabae, Bemisia tabaci, Orosius orientalis, Acheta domesticus, and Lasius niger were recorded on a weekly basis. The results showed that the mean abundances of E. fabae, O. orientalis, and B. tabaci were higher in the 30 × 50 cm plant spacing, whereas the 90 × 50 cm plant spacing resulted in a higher abundance of A. domesticus and L. niger. The measured agronomic traits, plant height (cm), plant dry mass (g), and total yield/ha (ton) of both the tomato varieties were significantly increased when the plants were spaced at 60 cm between plants and 50 cm between rows. We recommend that growing tomato plants at 60 cm between plants and 50 cm between rows may reduce the need to apply pesticides given that this plant spacing significantly reduced the abundance of some key insect pests and enhanced the tomato fruit yield.

Joint metabolome and transcriptome analysis of the effects of exogenous GA3 on endogenous hormones in sweet cherry and mining of potential regulatory genes.

Gibberellin (GA) is an important phytohormone that can participate in various developmental processes of plants. The study found that application of GA3 can induce parthenocarpy fruit and improve fruit set. However, the use of GA3 affects endogenous hormones in fruits, thereby affecting fruit quality. This study mainly investigates the effect of exogenous GA3 on endogenous hormones in sweet cherries. The anabolic pathways of each hormone were analyzed by metabolome and transcriptome to identify key metabolites and genes that affect endogenous hormones in response to exogenous GA3 application. Results showed that exogenous GA3 led to a significant increase in the content of abscisic acid (ABA) and GA and affected jasmonic acid (JA) and auxin (IAA). At the same time, the key structural genes affecting the synthesis of various hormones were preliminarily determined. Combined with transcription factor family analysis, WRKY genes were found to be more sensitive to the use of exogenous GA3, especially the genes belonging to Group III (PaWRKY16, PaWRKY21, PaWRKY38, PaWRKY52, and PaWRKY53). These transcription factors can combine with the promoters of NCED, YUCCA, and other genes to regulate the content of endogenous hormones. These findings lay the foundation for the preliminary determination of the mechanism of GA3's effect on endogenous hormones in sweet cherry and the biological function of WRKY transcription factors.

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

BackgroundFruit 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.ResultsFruit 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.ConclusionsThis 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.

Impact and packaging: do they affect fruit quality?

Impact and packaging: do they affect fruit quality?

The Molecular Network behind Volatile Aroma Formation in Pear (Pyrus spp. Panguxiang) Revealed by Transcriptome Profiling via Fatty Acid Metabolic Pathways.

Simple SummaryPear is a widely eaten fruit all over the world. Volatile aroma is an important factor affecting fruit quality and the fatty acid metabolism pathway is important in synthesizing volatile aromas. In this study, Panguxiang (Pyrus spp. Panguxiang) is a new variety bred from P. bretschneideri Rehd. cv. ‘Biyang piaoli’ and, unlike most white pear varieties cultivated in China, its aroma is also vital. The study aimed to explore unique pear resources of rich fruit aroma and to clarify the metabolism and regulation mechanism of the aromatic components in pear fruit. This paper used physiological and transcriptome methods to explore the molecular network behind volatile aroma formation in Panguxiang revealed via fatty acid metabolic pathways. Through transcriptome sequencing, weighted gene co-expression network analysis (WGCNA) identified yellow functional modules and several biological and metabolic pathways related to fatty acid formation. Finally, we identified seven and eight hub genes in the fatty acid synthesis and fatty acid metabolism pathways, respectively. Further analysis of the co-expression network allowed us to identify several key transcription factors related to the volatile aroma, including AP2/ERF-ERF, C3H, MYB, NAC, C2H2, GRAS, and Trihelix, which may also be involved in fatty acid synthesis and further influence the formation of aroma.Pears are popular table fruits, grown and consumed worldwide for their excellent color, aroma, and taste. Volatile aroma is an important factor affecting fruit quality, and the fatty acid metabolism pathway is important in synthesizing volatile aromas. Most of the white pear varieties cultivated in China are not strongly scented, which significantly affects their overall quality. Panguxiang is a white pear cultivar, but its aroma has unique components and is strong. The study of the mechanisms by which aroma is formed in Panguxiang is, therefore, essential to improving the quality of the fruit. The study analyzed physiological and transcriptome factors to reveal the molecular network behind volatile aroma formation in Panguxiang. The samples of Panguxiang fruit were collected in two (fruit development at 60, 90, 120, and 147 days, and fruit storage at 0, 7, 14, 21, and 28 days) periods. A total of nine sample stages were used for RNA extraction and paired-end sequencing. In addition, RNA quantification and qualification, library preparation and sequencing, data analysis and gene annotation, gene co-expression network analysis, and validation of DEGs through quantitative real-time PCR (qRT-;PCR) were performed in this study. The WGCNA identified yellow functional modules and several biological and metabolic pathways related to fatty acid formation. Finally, we identified seven and eight hub genes in the fatty acid synthesis and fatty acid metabolism pathways, respectively. Further analysis of the co-expression network allowed us to identify several key transcription factors related to the volatile aroma, including AP2/ERF-ERF, C3H, MYB, NAC, C2H2, GRAS, and Trihelix, which may also be involved in the fatty acid synthesis. This study lays a theoretical foundation for studying volatile compounds in pear fruits and provides a theoretical basis for related research in other fruits.

Role of tomato wild relatives in breeding disease-free varieties

Cultivated tomato (Solanum lycopersicum) is one of the most economically important and widely grown vegetable crops worldwide. However, tomato plants are often affected by biotic and abiotic stresses that reduce yield and affect fruit quality. Phenotypic diversity is evident in cultivated tomatoes, particularly for horticultural traits, but genetic diversity is rather narrow. Major disease resistance genes for different pathogens such as viruses, fungi, bacteria and nematodes are mainly derived from wild tomato species and introgressed into cultivated tomatoes. Here, we list the major disease and insect-pest resistance genes identified in S. pimpinellifolium, S. habrochaites, S. peruvianum, S. chilense, S. pennellii, S. galapagense, S. arcanum and S. neorickii with perspective on the gap between current knowledge on tomato wild relatives and the knowledge that is needed.

Blueberry endogenous ethylene production affects fruit quality and storability

Blueberry endogenous ethylene production affects fruit quality and storability

The Effect of Harvest Date and Storage Conditions on the Quality of Remontant Strawberry Cultivars Grown in a Gutter System under Covers

The storage characteristics of three remontant strawberry cultivars San Andreas®, Albion® and Murano® were studied in 2018–2020. The short-term storage conditions (7 days) of strawberries used in the study significantly affected fruit quality indicators. The highest quality of stored strawberries was provided by controlled atmosphere (CA) conditions, as evidenced by the typically highest fruit firmness and the lowest natural loss of strawberry weight. The modified atmosphere packaging (MAP) conditions obtained in the Xtend® bags provided a similar good storage effect for strawberries. Strawberries stored in MAP bags had the lowest respiratory intensity, and their firmness and the percentage of rotten fruit were the same as those stored in a controlled atmosphere. In addition, MAP bags were effective in reducing the weight loss of stored strawberries. The quality of strawberries stored in a conventional air storage (AA) was slightly lower compared to the fruit stored in a controlled and modified atmosphere. This was due to their lower firmness and significantly higher respiration intensity and higher weight loss. In addition, the percentage of rotten fruit, although low, has always been the highest among AA strawberries. The quality of the strawberries also depended on the date of fruit harvest. Strawberries harvested later, compared to those collected earlier, were generally characterized by higher firmness, lower acidity and lower respiration intensity.

Influences of Shading on Ascorbic Acid Biosynthesis of Blackcurrant (Ribes nigrum L.)

Cultivation conditions may greatly affect fruit quality, especially in the accumulation of functional metabolites. Blackcurrant fruits (Ribes nigrum L.) have high ascorbic acid (AsA) concentrations. The purpose of the current study was to investigate the influence of different shading treatments (full sunlight, and 40% and 60% sunlight) on the fruits’ maturity, and on the levels of fruit firmness, soluble solid, AsA, and enzyme activity involved in AsA biosynthesis and recycling in two blackcurrant (Ribes nigrum) cultivars, ‘Heifeng’ and ‘Adelinia’. Shading conditions of 40% and 60% sunlight delayed fruit ripening and increased fruit firmness in both ‘Adelinia’ and ‘Heifeng’. Soluble solids in ‘Adelinia’ were markedly reduced by shading compared with ‘Heifeng’. Compared with full sunlight, the AsA content was significantly decreased in the ripe fruits under the 40% and 60% shading treatments. Additionally, the AsA content was decreased during the fruit development process under the 60% shading treatment, which was associated with the reduced activity of the enzymes monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione oxidoreductase (GR), ascorbate peroxidase (APX), and L-galactose dehydrogenase (GalDH) involved in the biosynthesis and recycling pathway of AsA. The correlation analysis results showed that the activity of MDHAR, DHAR, GR, APX, and GalDH was significantly positively correlated with AsA concentrations during the 60% shading treatment in ‘Adelinia’ and ‘Heifeng’ fruits, suggesting that AsA biosynthesis and recycling were affected and the two cultivars have similar mechanisms to deal with shading. Our results not only provide a better understanding of the regulation mechanism of AsA accumulation under shading, but also provide a theoretical basis for taking effective cultivation measures aimed at the improvement of AsA levels in blackcurrant fruits.

A Horticultural Cuticle Supplement Can Impact Quality Characters and Drosophila suzukii Damage of Several Small and Stone Fruit.

Surface wax and other cellular building blocks play an important role in preserving fruit integrity from biotic and abiotic adversities. Huge energy expenses are made by plants to place these protective compounds onto the epidermal cuticle. Sprayable plant and fruit coatings have been developed to protect plant tissues from environmental stresses, pathogens, and arthropods. The aim of this study was to determine if an experimental cuticle supplement containing waxes can affect fruit quality parameters such as firmness and size of various crops. Cherry, blueberry, and winegrape plants treated with the cuticle supplement showed significant increases in berry firmness ranging from 4.6 to 11.6%. No quality benefits were however observed on blackberry. Cuticle supplement applications did not significantly affect berry size. Laboratory trials resulted in a 54% mean reduction in a model pest insect i.e., Drosophila suzukii egg laying on blueberry. Short-duration field trials over 72 ± 2 to 96 ± 2 h on commercial-standard blueberry bushes resulted in 50-93.4% reductions of D. suzukii damage. Longer-term field trials on cherry and blueberry challenged with egg-laying D. suzukii showed reductions of damage ranging from 45 to 95%, up to 30 d after initial cuticle supplement applications. These results indicate that the cuticle supplement significantly alters berry firmness and reduces D. suzukii damage under commercial production conditions. One factor that may contribute to this reduction includes improved fruit quality parameters. The current work serves to expand integrated pest management options to control D. suzukii populations in commercial field settings.

Hydraulic Trait Variation with Tree Height Affects Fruit Quality of Walnut Trees under Drought Stress

Persian or common walnut (Juglans regia L.) is a fruit tree of significant agricultural importance and is considered highly drought-resistant. However, the effects of different irrigation treatments and tree height on the physiology, growth and fruit quality of the walnut tree remain largely elusive. In the presently study, we selected ‘Wen 185’, one of the main walnut cultivars, as the target plant species. We established three irrigation treatments (deficit (DI), conventional (CI) and excess irrigation (EI)) from April to September of 2020 and measured leaf hydraulic traits, photosynthetic characteristics, soluble sugar (SS) content, leaf area, branch growth, fruit morphology and the no and deflated kernel (NDK) rate of walnut trees in each treatment. Our results showed that: (1) midday leaf water potential (Ψmd) decreased significantly under the DI treatment and declined significantly with increasing tree height; upper canopy Ψmd in the DI group decreased by 18.40% compared to the lower canopy; (2) the light compensation point, light saturation point, maximum net photosynthetic rate, maximum photochemical efficiency and chlorophyll SPAD values of trees in the DI group decreased slightly but did not differ significantly from the CI and EI treatments; (3) reduced irrigation did not significantly affect the soluble sugar content of leaves (LSs) and fine roots (RSs), but the soluble sugar content of walnut kernels (FSs) was significantly higher in the DI treatment than under the CI and EI treatments and also increased with tree height; the average soluble sugar content across heights was 6.61% in the EI group, 7.19% in the CI group and 9.52% in the DI group; (4) branch terminal leaf area (LA) was significantly reduced at the end of new branches, and Huber values (HV) were significantly higher under the DI treatment; compared to the EI group, LA was reduced by 52.30% in the DI group and 32.50% in the CI group; HV increased by 79.00% in the DI group and 15.70% in the CI group; (5) reduced irrigation did not significantly affect fruit morphology but did increase the NDK rate of walnuts, which also increased with tree height; the average NDK rate across all heights was 4.63% in the EI group, 5.04% in the CI group, and 8.70% in the DI group; the NDK rate was 41.75% higher in the upper part of the canopy compared to the lower part in the DI group. Our results indicate that walnut trees suffer greater water stress in the upper canopy than in the middle and low parts of the canopy. By increasing HV, walnut trees maintained relatively stable photosynthetic capacity under drought. However, water deficit had a significant effect on NDK rates, particularly at greater tree heights.

Tomato Oxalyl-CoA Synthetase Degrades Oxalate and Affects Fruit Quality.

Acyl activating enzyme 3 (AAE3) encodes oxalyl-CoA synthetase involved in oxalate degradation. In this study, we investigated the role of AAE3 (SlAAE3) in the fruit quality of tomato (Solanum lycopersicum). The purified recombinant SlAAE3 protein from Escherichia coli exhibited a high activity toward oxalate, with a Km of 223.8 ± 20.03 μm and Vmax of 7.908 ± 0.606 μmol mg–1 protein min–1. Transient expression of SlAAE3-green fluorescent protein (GFP) fusion proteins suggests that SlAAE3 is a soluble protein without specific subcellular localization. The expression of SlAAE3 is both tissue- and development-dependent, and increased during fruit ripping. The Slaae3 knockout mutants had improved fruit quality as evidenced by the increased sugar-acid ratio and mineral nutrient content. To find the mechanism by which SlAAE3 affects fruit quality, transcriptome, and metabolome were employed on SlAAE3 over-expressed line and wide type fruits. The transcriptomic and metabolic profiles indicated that SlAAE3 in fruits mainly functions at 20 days post-anthesis (20 DPA) and mature green (MG) stages, resulting in up-regulation of amino acid derivatives, nucleotides, and derivatives, but down-regulation of lipid compounds. However, differentially expressed genes (DEGs) were mainly enriched at redox pathways. Taken together, both in vivo and in vitro results suggest that SlAAE3-encoded protein acts as an oxalyl-CoA synthetase, which also participates in redox metabolism. These data provide a further understanding of the mechanism by which SlAAE3 participates in tomato fruit quality.

Large-Scale, High-Throughput Phenotyping of the Postharvest Storage Performance of 'Rustenburg' Navel Oranges and the Development of Shelf-Life Prediction Models.

We conducted a large-scale, high-throughput phenotyping analysis of the effects of various pre-harvest and postharvest features on the quality of ‘Rustenburg’ navel oranges, in order to develop shelf-life prediction models to enable the use of the First Expired, First Out logistics strategy. The examined pre-harvest features included harvest time and yield, and the examined postharvest features included storage temperature, relative humidity during storage and duration of storage. All together, we evaluated 12,000 oranges (~4 tons) from six different orchards and conducted 170,576 measurements of 14 quality parameters. Storage time was found to be the most important feature affecting fruit quality, followed by storage temperature, harvest time, yield and humidity. The examined features significantly affected (p < 0.001) fruit weight loss, firmness, decay, color, peel damage, chilling injury, internal dryness, acidity, vitamin C and ethanol levels, and flavor and acceptance scores. Four regression models were evaluated for their ability to predict fruit quality based on pre-harvest and postharvest features. Extreme gradient boosting (XGBoost) combined with a duplication approach was found to be the most effective approach. It allowed for the prediction of fruit-acceptance scores among the full data set, with a root mean square error (RMSE) of 0.217 and an R2 of 0.891.