Peel Color Research Articles

INVESTIGATION OF THE SHELF LIFE OF BANANA ‘MAS’ (Musa acuminata Colla) USING GAMMA IRRADIATION

To investigate the shelf life of banana ‘Mas’ (Musa acuminata Colla) using gamma rays in Malaysia. An experimental study to investigate the shelf life of banana Mas using different doses of gamma radiation. Different doses will be given to each group of banana Mas which are 0 (untreated control), 0.4, 0.8 and 1.2 kGy. The irradiated groups were being irradiated by gamma radiation at the National University of Malaysia (UKM) using Gamma Cell 220 Excel Cobalt-60 source. The observation was performed on the physical changes of the sample such as peel colour, decay rate, and physiological weight loss. Findings have shown that the high dose of gamma radiation caused the darkening of the peel and accelerate the ripening process depend on the varieties of the bananas. Among all, group B (0.4 kGy) has the lowest PWL (Physiological Weight Loss) and decay rate when compared to the other groups. The result of the one-way ANOVA test on the weight loss was not statistically significant. The dose of 0.4 kGy was the most effective one in delaying the ripening process for banana Mas when compared to the other group samples.

Genomic Approaches for Improvement of Tropical Fruits: Fruit Quality, Shelf Life and Nutrient Content.

The breeding of tropical fruit trees for improving fruit traits is complicated, due to the long juvenile phase, generation cycle, parthenocarpy, polyploidy, polyembryony, heterozygosity and biotic and abiotic factors, as well as a lack of good genomic resources. Many molecular techniques have recently evolved to assist and hasten conventional breeding efforts. Molecular markers linked to fruit development and fruit quality traits such as fruit shape, size, texture, aroma, peel and pulp colour were identified in tropical fruit crops, facilitating Marker-assisted breeding (MAB). An increase in the availability of genome sequences of tropical fruits further aided in the discovery of SNP variants/Indels, QTLs and genes that can ascertain the genetic determinants of fruit characters. Through multi-omics approaches such as genomics, transcriptomics, metabolomics and proteomics, the identification and quantification of transcripts, including non-coding RNAs, involved in sugar metabolism, fruit development and ripening, shelf life, and the biotic and abiotic stress that impacts fruit quality were made possible. Utilizing genomic assisted breeding methods such as genome wide association (GWAS), genomic selection (GS) and genetic modifications using CRISPR/Cas9 and transgenics has paved the way to studying gene function and developing cultivars with desirable fruit traits by overcoming long breeding cycles. Such comprehensive multi-omics approaches related to fruit characters in tropical fruits and their applications in breeding strategies and crop improvement are reviewed, discussed and presented here.

Codification and description of the phenological growth stages of red-fleshed pitaya (Hylocereus polyrhizus) using the extended BBCH scale- with special reference to spines, areole, and flesh color development under field conditions

Pitaya (Hylocereus spp.) has become a global fruit crop, particularly in Southeast Asia, with two main species cultivated over recent decades; the white-fleshed pitaya (H. undatus) and the red-fleshed pitaya (H. polyrhizus). Although the morphological description of the phenological stages of white-fleshed pitaya (H. undatus) has been recorded using a three-digit numerical system as per the Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale rule; however, the description of spine development, an important characteristic of bud burst under the areole is lacking. Additionally, the description scale for flesh color change caused by the accumulation of the betalain pigment, which is important for its nutrition value in red-fleshed pitaya, is lacking. This study investigated the phenological stages of a red-fleshed pitaya, an allied species with remarkable similarity to white-fleshed pitaya, “Da Hong” (also called “Big Red”), using the BBCH scale to provide uniform phenology-related information and develop a more suitable scale for the scientific studies and crop practices of red-fleshed pitaya. Furthermore, at each stage, the development of the spine and flesh color to address fruit developmental characteristics owing to its red flesh was simultaneously assessed and recorded. The flesh started to grow at the first stage of fruit development (code 711). The flesh color changed at the final phase of fruit development (code 719) and at the first phase of fruit peel maturity (code 811). The peel color in the flesh and mesocarp changed completely in the final phase (code 819), indicating the completion of fruit maturity. This important phenological stage scale may be used in growth, development, and physiology studies, and in orchard management, including field practice, nutrition management, and pest and disease control.

‘d’Anjou’ pear metabolism during ultra-low O2, low CO2 controlled atmosphere storage reflects disorder outcome

With increasingly restrictive regulation of postharvest crop protectants and expected year-round availability, pear (Pyrus communis L.) production is ever more reliant on precise controlled atmosphere (CA) storage technologies to provide both ripening and disorder control for long term storage. Ultra-low oxygen (ULO; <1 kPa O2) CA storage meets many of these criteria affording control of ripening and superficial scald. However, internal browning often is an unintended outcome caused by atmospheric conditions and other events that occur, similarly to superficial scald, prior to symptom development. While this is often associated with elevated CO2, it also can occur at lower partial pressures (<0.5 kPa CO2) reducing its widespread use for storing pears. We expected levels of specific metabolites in ‘d’Anjou’, a cultivar susceptible to both disorders, would reflect specific disorder risk under ULO and low CO2. The metabolic profile of pear peel stored at 0.5 °C in air, CA (1.5 kPa O2; 0.5 kPa CO2), or ULO (determined in the first week of storage by monitoring chlorophyll fluorescence; 0.5 kPa O2; 0.5 kPa CO2) was compared at multiple time points during 0−16 weeks storage. Final fruit quality and relative ripeness were assessed at 16 weeks plus 7 d at 20 °C. Quality and ripeness differences and related metabolism followed that established in existing literature regarding peel color, titratable acidity, ethylene evolution, respiration, and sucrose metabolism. Superficial scald developed on air stored fruit and core browning incidence most in pears stored in 0.4 kPa O2. α-Farnesene oxidation increased most in air followed by 1.5 kPa O2 storage indicating risk of this disorder on fruit from those storage conditions. As in other studies, γ-aminobutyric acid (GABA) was elevated most where internal browning had occurred, although levels were also elevated in the peel. Levels of glutamic acid, alanine, and, unique to this study, proline were also most elevated in peel from pears stored in 0.5 kPa O2 indicating their association with conditions that lead to core browning. Monitoring α-farnesene oxidation coupled with GABA, glutamic acid, alanine, and proline levels in peel may be a means to indicate whether ULO CA atmospheres with reduced CO2 levels are accomplishing the critical task of controlling pear superficial scald without causing internal browning before injury occurs.

Influence of pre-harvest fruit bagging and plant cover on peel colour, physical appearance and quality traits of pomegranate fruits in arid conditions

Aim: To study the influence of fruit bagging and plant cover on microclimate modification and its role on external quality traits and physico-chemical fruit characteristics of pomegranate cv. Bhagwa in arid conditions. Methodology: Fruits bagging was done with single layer bags of news paper (NP), brown paper (BP), white parchment paper (PP), non-woven polypropylene (NWP), complete plant covering with non-woven polypropylene (CNWP), and un-bagged with no cover was kept as control. Bagging was done 60 days after fruit set and continued until harvest, each year. Results: Bagging and plant covering modified the microenvironment which positively influenced the fruit development. Among the bags, inside air temperature was higher in BP followed by NP, PP and NWP, while RH was higher in PP. PP bags was most effective for the development of attractive red peel color (a* value = 44.4) followed by NWP (a* value = 39.6) or CNWP (a* value = 36.6). All four bags were able to check thrips incidence completely, while PP bagging provided physical scratches or fungal spot free fruits. Physical attributes of fruits including fruit weight, aril weight, peel thickness and juice content were considerably affected. Interpretation: Fruit bagging or plant covering is simple, cost-effective and eco- friendly way to produce quality safe pomegranate fruits under adverse climatic conditions of arid regions.

The Transcriptome and Metabolome Reveal Stress Responses in Sulfur-Fumigated Cucumber (Cucumis sativus L.).

Sulfur (S) fumigation is a commonly used sterilization method in horticultural facilities against fungal diseases. S fumigation damaged cucumber leaves, although the response mechanism is unclear. This study analyzes the growth, transcriptome, and metabolomic profiles of young and mature leaves, ovaries, and commercial cucumber fruits to decipher the mechanism of cucumber stress response under S fumigation. S fumigation significantly changed the photosynthetic efficiency and reactive oxygen species (ROS) in leaves, but not fruit development, fruit mass, and peel color. Transcriptome analysis indicated that S fumigation strongly regulated stress defense genes. The weighted gene co-expression network analysis revealed that S fumigation regulated ASPG1, AMC1 defense genes, LECRK3, and PERK1 protein kinase. The abscisic acid (ABA)-mediated model of regulation under S fumigation was constructed. Metabolome analysis showed that S fumigation significantly upregulated or downregulated the contents of amino acids, organic acids, sugars, glycosides, and lipids (VIP > 1 and P-value < 0.05). The opposite Pearson’s correlations of these differential metabolites implied that cucumber had different metabolic patterns in short-term and long-term S fumigation. Besides, the elevated levels of proline and triglyceride indicated that stress-responsive mechanisms existed in S-fumigated cucumber. Moreover, the comprehensive analysis indicated that S fumigation elevated secondary S-containing metabolites but decreased sulfate absorption and transportation in cucumber. Overall, our results provided a comprehensive assessment of S fumigation on cucumber, which laid the theoretical foundation for S fumigation in protected cultivation.

QTL mapping and transcriptome analysis to identify genes associated with green/russet peel in Pyrus pyrifolia

Peel colour is a very important appearance quality and is strongly associated with commercial value. Green, russet and partially russet peels are observed in the fruit of Pyrus pyrifolia. Currently, the mechanisms of peel russeting in fruit development are still uncertain. Two pear cultivars, ‘Zaoshengxinshui’ (russet peel) and ‘Qiushui’ (green peel), and 92 offspring were sequenced by specific-locus amplified fragment sequencing (SLAF-seq) to isolate SNPs to identify the QTLs. The results showed that 8,545 SLAF tags were used to construct the genetic map with a genetic distance of 2,486.18 cM. Two QTLs were related to peel colour: qColour-LG9.1 and qColour-LG9.2 (LOD >5.2). A total of 73 and 64 genes were annotated in qColour-LG9.1- and qColour-LG9.2-related chromosome regions, respectively. Transcriptome analysis revealed the expression of all genes. Four differentially positively expressed genes, PpRAX3, PpHAT22, PpKN1, and PpC3H23, were found in the qColour-LG9.1-related chromosome region. The transient overexpression of these genes showed that PpC3H23 could increase the peel russeting ratio, thus implying that PpC3H23 might play important roles in peel russeting. Transcriptome analysis also found 403 differentially expressed genes in peel russeting, including transcription factors (MYB, HD, and BHLH) and functional genes related to fatty acid, glycerolipid, cutin, suberine and wax biosynthesis (GDSL, KCS, GPAT, HHT, etc.). Altogether, the results of the present study provide new insights into the molecular mechanism underlying peel russeting in P. pyrifolia.

Integrated Analysis of the Metabolome and Transcriptome on Anthocyanin Biosynthesis in Four Developmental Stages of Cerasus humilis Peel Coloration.

Cerasus humilis is a unique dwarf shrub and fruit color is an important trait in the species. In this study, we evaluated the transcriptomic and metabolomic profiles of the plant at different developmental stages to elucidate the mechanism underlying color formation. In a metabolomics analysis, 16 anthocyanin components were identified at four developmental stages, and high levels of cyanidin O-syringic acid and pelargonidin 3-O-beta-d-glucoside (callitephin chloride) were correlated with the reddening of the fruit peel. A co-expression analysis revealed that ANS and UFGT play key roles in pigmentation (PCC > 0.82). Additionally, transcriptome data showed that most anthocyanin biosynthetic genes and two MYB transcription factors were significantly up-regulated. QRT-PCR results for these differentially expressed genes were generally consistent with the high-throughput sequencing. Moreover, the overexpression of ChMYB1 (TRINITY_DN21536_c0_g1) in apple calli could contribute to the accumulation of anthocyanin. It was also found that UFGT (TRINITY_DN19893_c1_g5) and ChMYB1 (TRINITY_DN21536_c0_g1) have similar expression patterns. These findings provide insight into the mechanisms underlying anthocyanin accumulation and coloration during fruit peel development, providing a basis for the breeding of anthocyanin-rich C. humilis cultivars.

Bioactive Compounds, Sugars, and Sensory Attributes of Organic and Conventionally Produced Courgette (Cucurbita pepo).

Organic agriculture is considered one of the elements of sustainable food production and consumption, mainly due to its limited impact on the natural environment. At the same time, the quality features of organically produced foods, especially sensory attributes and health promoting values, are important factors determining consumers’ interest, and therefore play a key role in the organic sector’s development. The aim of this study was to investigate the sensory characteristics and concentrations of sugars and selected health-promoting bioactive compounds of organic courgette compared to conventionally grown courgette. In addition, untargeted metabolomic analysis of the courgette fruits was performed. The results of this study did not show a significant effect of the horticultural system (organic vs. conventional) on the concentrations of vitamin C, carotenoids, and chlorophylls in the courgette fruits. However, the fruits from the organic systems were significantly richer in sugars when compared to the conventionally cultivated ones (p = 0.038). Moreover, the organic fruits fertilized with manure contained significantly higher amounts of polyphenols, including gallic acid (p = 0.016), chlorogenic acid (p = 0.012), ferulic acid (p = 0.019), and quercetin-3-O-rutinoside (p = 0.020) compared to the conventional fruits. The untargeted analysis detected features significantly differentiating courgette fruits depending on the cultivar and horticultural system. Some significant differences in sensory values were also identified between fruits representing the two cultivars and coming from the horticultural systems compared in the study. Conventional courgettes were characterized by the most intensive peel color and aquosity, but at the same time were the least hard and firm compared to the fruits from the two organic systems. There was also a trend towards higher overall quality of the organically grown fruits. The presented study shows that the organic and conventional courgette fruits differ in a number of quality features which can influence consumers’ health and purchasing choices.

Ethyl Formate as a Methyl Bromide Alternative for Fumigation of Citrus: Efficacy, Fruit Quality, and Workplace Safety.

Ethyl formate (EF) was evaluated as a potential alternative to methyl bromide (MB) for phytosanitary treatment of imported citrus fruit in the Republic of Korea. Planococcus citri (Risso) (Hemiptera: Pseudococcidae), a mealybug with known tolerance against EF and MB, was used as a representative pest to test efficacy of the two fumigants against eggs. In nine commercial-scale refrigerated container (67.5 m3) trials using imported orange, lemon and grapefruit, EF applied at the currently approved dose for citrus (70 g·m-3 at 5°C for 4 h, developed for Aspidiotus excisus Green (Hemiptera: Diaspididae), a species less EF tolerant than P. citri) resulted in 76.9-98.3% mortality of P. citri eggs. The EF treatment did not affect the sugar content or the color of peel and pulp of the treated fruit. When oranges were treated according to the current MB (64 g·m-3 at >5°C for 2 h) or EF treatment guidelines, the concentration of fumigant around the fruit fluctuated between 9.4 and 185.1 ppm for EF and 9.5-203.0 ppm for MB during the 72-h post-fumigation processes (venting [0-2 h], transportation to storage [2-24 h], and storage periods [24-72 h]) with both EF and MB maintained between 10 and 100 ppm during the storage period. Considering the efficacy of EF, its apparent lack of phytotoxicity, and its more manageable threshold limit value for humans (100 ppm EF compared to 1 ppm MB for an 8-h time weighted average exposure), our results suggest that EF may be a promising alternative to MB for the phytosanitary treatment of imported citrus in Korea.

Identification and Application of BhAPRR2 Controlling Peel Colour in Wax Gourd (Benincasa hispida).

Peel color is an important factor affecting commodity quality in vegetables; however, the genes controlling this trait remain unclear in wax gourd. Here, we used two F2 genetic segregation populations to explore the inheritance patterns and to clone the genes associated with green and white skin in wax gourd. The F2 and BC1 trait segregation ratios were 3:1 and 1:1, respectively, and the trait was controlled by nuclear genes. Bulked segregant analysis of both F2 plants revealed peaks on Chr5 exceeding the confidence interval. Additionally, 6,244 F2 plants were used to compress the candidate interval into a region of 179 Kb; one candidate gene, Bch05G003950 (BhAPRR2), encoding two-component response regulator-like protein Arabidopsis pseudo-response regulator2 (APRR2), which is involved in the regulation of peel color, was present in this interval. Two bases (GA) present in the coding sequence of BhAPRR2 in green-skinned wax gourd were absent from white-skinned wax gourd. The latter contained a frameshift mutation, a premature stop codon, and lacked 335 residues required for the protein functional region. The chlorophyll content and BhAPRR2 expression were significantly higher in green-skinned than in white-skinned wax gourd. Thus, BhAPRR2 may regulate the peel color of wax gourd. This study provides a theoretical foundation for further studies of the mechanism of gene regulation for the fruit peel color of wax gourd.

THE PHYSICAL AND CHEMICAL PROPERTIES OF THE JUJUBE FRUITS AT DIFFERENT MATURATION STAGES

The effects of maturation stages on some physical and chemical properties of the jujube fruits were investigated. The maturation stages of the jujube fruits were described as green, yellow, half-red and red maturation. The physical properties and chemical composition of the jujube fruit significantly changed depending on the maturation stage. The size and weight of the jujube fruits increased, and the peel color changed from green to red with the maturation. The content of water-soluble vitamins, trans-resveratrol, total phenolic content and antioxidant capacity of the jujube fruits decreased during the maturation. The trans-resveratrol content of the jujube fruits was investigated for the first time and no trans-resveratrol content could be detected at red maturation stage. The major organic acid and sugar at the red maturation stage were found to be malic acid and sucrose, respectively. The phenolic composition also changed, but these changes showed unstable trend during the maturation. The major phenolic compound was catechin at the green maturation stage, whereas chlorogenic acid dominated at the red maturation stage. The jujube fruit is rich in minerals especially potassium and no changes in the mineral contents except for copper was observed between green and red maturation stages.

Evaluating the response of insecticides and fungicides for rind blemishes management in Kinnow mandarin (Citrus nobilis Lour × Citrus deliciosa Tenora) fruits caused by biotic factors

Kinnow mandarin being produced in Pakistan faces different quality issues ending up in poor rind quality bearing blemishes on the peel. The main reason behind quality issues is inadequate production management including unoptimized production technology with an inappropriate spray schedule of insecticides and fungicides. Major blemishes found on the surface of fruit are biotic in nature (diseases and insects) and generally appear during the early 8-12 weeks of fruit setting. The objective of this study was to optimize insecticides and fungicides to manage rind blemishes in ‘Kinnow’ mandarin fruits caused by biotic factors. The present study was conducted during 2017-2018; there were four kinds of pesticides such as Actara (Thiamethoxam) or Confidor (Imidacloprid) and Nativo (Tebuconazole and Trifloxystrobin) or Topsin M (Thiophanate-methyl) sprayed to the trees at onset of fruit setting. The extent and nature of blemishes related to diseases and insects were significantly reduced after the spray of 0.3 g L-1 Nativo, 1.5 ml L-1 Confidor as compared to the application of Actara (0.24 g L-1 water) and Topsin M (2 g L-1 water), while the higher extent of blemishes was recorded in control block. Surface smoothness and peel colour of fruits showed significant improvement in sprayed trees compared to control. Likewise, preharvest sprays reduced the post-bloom and commercial fruit drop, resulting in a high yield per tree. However, the preharvest sprays showed a non-significant effect on organoleptic quality and biochemical attributes of ‘Kinnow’ fruit. Conclusively, the combination of Confidor (1.5 ml L-1 water) and Nativo (0.3 g L-1 water) sprays at fruit setting stage could be helpful in managing biotic blemishes in ‘Kinnow’ mandarin fruits resulted in an increased proportion of A-grade quality fruits in final pack out.

Effects of mode and timing of calcium chloride application on tissue calcium concentration and acceptability of mango fruits

Mango (Mangifera indica L) production in Kenya directly supports approximately 200,000 farmers and many other beneficiaries. Despite this, its production suffers from post-harvest losses due to the fruits' short shelf life in ambient conditions. Calcium maintains cell integrity, strengthens the cell wall, membrane structure, and thus increases shelf life. A completely randomized block design with a split plot arrangement was used to compare the effect of spraying and immersion of ‘Van Dyke' mango fruits at maturity or 15 days later in calcium chloride at different concentrations (0.5%, 1%, 1.5%, or 0%) and times on the fruit ripening rate and organoleptic acceptance. The peel firmness (N), total soluble solids (0Brix), flesh color (Ho), beta carotene (mg/100ml), and carbon dioxide evolution (ml/kg/hr) of fruits were determined at time 0 and every two days for up to eight days in ambient conditions. Additionally, organoleptic characteristics, flesh firmness, calcium concentration (g/mg), and their correlations were determined. Fruits immersed in calcium chloride at maturity had higher retained peel firmness (10.6 N, 10.3 N), deeper flesh color (37.45, 36.78), lower total soluble solids (14, 13.8), a lower carbon dioxide evolution (30.7 ml/kg/hr), higher beta carotene and higher flesh calcium concentration than fruits exposed to other treatments. Fruits sprayed at maturity outperformed those sprayed 15 days later in the studied parameters. Flesh calcium content correlated positively with flesh firmness (r= 0.913, r= 0.852), flesh color (r= 0.828, r= 0.841), fruit aroma (r=0.8199, r=0.841), and negatively with skin shriveling (r=-0.778, r=-0.806) and fruit flavor (r=-0.811, r=-0.829). Flesh firmness correlated negatively with skin shriveling (r=-0.868, r=-0.788) and fruit flavor (r=-0.8869, r=-0.821), but positively with peel color (r=0.9115, r=0.856) and aroma (r=0.907, r=0.848). Skin shriveling was found to have a negative relationship with peel color (r=-0.944, r=-0.93) and aroma (r=-0.944, r=-0.938), but a positive relationship with fruit flavor (r=0.933, r=0.947). Peel color correlated positively with aroma (r=0.979, r=0.977) and negatively with fruit flavor (r=-0.962, r=-0.950), respectively. Despite the effectiveness of post-harvest calcium chloride immersion in extending fruit shelf life, optimal use is advised to avoid deteriorated pulp flavor and increased shriveling. More research is needed to determine how calcium chloride can be made available to the fruit while it is still attached to the tree.

Comparative metabolomics and sensory evaluation of pineapple (Ananas comosus) reveal the importance of ripening stage compared to cultivar

The pineapple ripening stage is determined at the time of harvest and can be classified into the C0 to C4 stage based on its peel color. C1 and C4 pineapples are the most commonly exported products with high demand. Pineapple also has many cultivars with different tastes and appearances. However, there are limited studies regarding the metabolite and taste profiles of pineapple from different cultivars and ripening stages using a metabolomics approach. Therefore, the objective of this study was to investigate the metabolite and sensory profiles of pineapple from different cultivars and different ripening stages. Three cultivars of pineapple (Red Spanish, Smooth Cayenne, and Queen) and C1, C3, and C4 stages from Indonesia, Japan, the Philippines, and Taiwan, respectively, were analyzed by gas chromatography/mass spectrometry (GC/MS). The data obtained from GC/MS analysis were combined with the data obtained from sensory evaluation, which showed that sourness and firmness contributed to C1 fruits with metabolites correlated to isocitric acid+citric acid, malic acid, ascorbic acid, and quinic acid, while sweetness, juiciness, and high acceptability contributed to C4 fruits with metabolites that correlated were asparagine, serine, glycine, threonic acid, sucrose, and 5-hydroxytryptamine. GC/MS analysis using different pineapple cultivars also showed characteristic metabolites for each cultivar. Prediction of the sensory profile was performed by investigating the relative intensity of taste-related metabolites. This information can provide a basis for improving pineapple taste quality related to metabolites, depending on the cultivar and ripening stage.

PME and CaCl2 vacuum infusion maintains the firmness and physicochemical characteristics of tomato fruits

Tomato is a fruit of great commercial importance and highly cultivated. However, postharvest losses represent one of the main problems of this crop and can be minimized as alternative techniques. Therefore, the objective of the present work was to maintain tomato firmness by applying calcium chloride-associated pectin-methylesterase (PME) by the vacuum infusion method. Tomatoes of cultivar IAP-6 were submitted to vacuum infusion with water, vacuum infusion with 5% calcium chloride and vacuum infusion with PME associated with 5% calcium chloride, fruits without infusion were used as control. Fresh mass loss, fruit firmness, peel color, soluble solids content, pH, total acidity, PME activity and calcium activity were evaluated. The experiment was carried out in a completely randomized design in a 4x5 factorial scheme with three replications for 12 days, evaluated every 3 days. The means were compared using the Tukey test (p &lt;0.05). Data were analyzed graphically with confidence interval (CI p &lt;0.05). Regarding the loss of fresh mass there was an increase over time in all treatments. The PME + CaCl2 5% treatment was the most suitable for reducing firmness loss, as well as presenting the smallest variation of PME activity, as well as low levels of organic acids. Therefore, vacuum infusion with PME + CaCl2 in tomatoes maintains acceptable firmness and physicochemical characteristics as well as CaCl2 infusion.

Physicochemical Changes, Peel Colour, and Juice Attributes of Blood Orange Cultivars Stored at Different Temperatures

Changes in physicochemical traits, peel colour, and juice attributes of four blood orange cultivars (‘Moro’, ‘Tarocco’, ‘Sanguinello’, and ‘Sanguine’) were evaluated during 180 days at 2 and 5 °C plus 2 days at 20 °C for shelf life. ‘Tarocco’ had the lowest weight and firmness losses at both temperatures during storage. Titratable acidity (TA) at 5 °C was higher than 2 °C, with ‘Sanguinello’ and ‘Tarocco’ showing the highest and lowest TA, respectively. Juice content decreased during storage at both temperatures, although ‘Sanguinello’ had the highest juice content among the tested cultivars. Peel colour parameters including L* (lightness), b*, hue angle (h°), and chroma (C*) decreased during cold storage, while a* and citrus colour index (CCI) increased in all cultivars at both temperatures. The order for CCI was ‘Tarocco’ &gt; ‘Moro’ &gt; ‘Sanguinello’ &gt; ‘Sanguine’. Overall, prolonged storage at 5 °C was considered as optimum temperature for all cultivars, although ‘Sanguinello’ cultivar had a better aptitude for the citrus juice industry.

PbWRKY75 promotes anthocyanin synthesis by activating PbDFR, PbUFGT, and PbMYB10b in pear.

Anthocyanins are common secondary metabolites in plants that impart red coloration to fruits and flowers. The important WRKY transcription factor family plays multifaceted roles in plant growth and development. In this study, we found a WRKY family gene, Pyrus bretschneideri WRKY75, that may be involved in anthocyanin synthesis in pear. Unlike Arabidopsis thaliana WRKY75, PbWRKY75 may be a positive regulator of anthocyanin synthesis. A transient expression assay indicated that PbWRKY75 promoted pear anthocyanin synthesis. The structural genes (PbANS, PbDFR, and PbUFGT) and positive regulators (PbMYB10 and PbMYB10b) of anthocyanin synthesis were significantly upregulated in the fruitlet skins of PbWRKY75-overexpressing "Zaosu" pears. Subsequently, yeast one-hybrid and dual-luciferase assays indicated that PbWRKY75 promoted PbDFR, PbUFGT, and PbMYB10b expression by activating their promoters. These results revealed that PbWRKY75 may promote the expression of both PbMYB10b and anthocyanin late biosynthetic genes (PbDFR and PbUFGT) by activating their promoters, thereby inducing anthocyanin synthesis in pear. This study enhanced our understanding of the mechanism of pear anthocyanin synthesis, which will be beneficial in the improvement of pear peel color.

Comparing the number of Iranian pomegranate genotypes based on morphological and biochemical properties

Punica granatum L. is one of the oldest known edible fruits. Numerous chemical compounds have been isolated from pomegranate seeds, juice, and peels, which have beneficial effects on human health. This study aimed to perform the physicochemical and morphological properties of twenty-four pomegranate genotypes from various provinces of Iran. Fifteen fruits of each cultivar are collected at harvest maturity in the normal ripening period for the pomegranate from the Iranian pomegranate genetic collection in Yazd, Iran. Five fruits were randomly harvested from each of four orientations of the tree, and were immediately taken to the laboratory for analysis. Three replicates were maintained for each analysis. The results indicated the highest levels of anthocyanin was observed in S783 and R633, while polyphenols in Q529, the antioxidant capacity in N755 and the total soluble solids levels in R633 and the total acidity levels were found in K477 and E336. On the other hand, the fruit weight (in S948), fruit diameter (in SH1738), crown diameter (in R533), total weight of the seeds (in S948), peel thickness (in S716), peel colour (in S948), and red juice (in S783) are significantly affected by the genotype. At a similarity of 50%, the genotypes were divided into nine sub-clusters including A, B, C, D, E, F, G, H and I. These identified genotypes can be rolled out in future breeding programmes.

Citrus black spot severity related to premature fruit drop in sweet orange orchards

AbstractCitrus black spot (CBS) may cause substantial yield loss in sweet orange orchards. Severity and distribution of CBS symptoms on fruit may be variable and not all affected fruit may fall. However, the relationship between CBS symptoms and yield loss has not yet been investigated. This study aimed to determine CBS characteristics associated with premature fruit drop. A set of fruit was removed from the tree to measure the detachment force and another set of dropped fruit was collected from Pera and Valencia sweet orange orchards in three municipalities in Sao Paulo state, Brazil. CBS severity, distance of the nearest lesion from the peduncle, and fruit peel colour were assessed in both fruit sets. CBS severity was consistently related with the force to remove fruit and hence associated to the premature fruit drop, irrespective of the cultivar and location. The segmented linear regression showed that the fruit detachment force was reduced abruptly, at a rate of 7% for every 1% increase in disease severity up to 4.2 ± 1.0% CBS severity and, above this breakpoint, the force decreased slightly at a rate of 1.5%. Taking into account all orchards, the proportion of dropped fruit with CBS severity higher than the breakpoint was approximately 90%. This study provides a better understanding of the relationship between CBS severity and premature fruit drop of sweet orange. CBS severity breakpoint may be used as a reference to anticipate harvest and reduce CBS‐related yield loss in orchards intended for juice processing.