Flesh Tissue Research Articles

BIOTECHNOLOGICAL BASICS AND PRACTICAL METHODS OF PROCESSING COLLAGEN-CONTAINING RAW MATERIALS FROM POULTRY

Subject. The resources of collagen-containing raw materials are significant. These also include processed poultry products, which are used only for feed purposes or are generally disposed of. Therefore, it is necessary to use special methods for processing these collagen-containing raw materials, in particular chicken legs, to obtain a protein product with appropriate functional and technological parameters. Today there are many ways to influence collagen-containing raw materials and obtain collagen preparations for use in the food industry, cosmetology, medicine, etc. Purpose. The purpose of the work is to scientifically substantiate and experimentally confirm the possibility of obtaining high-quality protein products from collagen-containing raw materials (including chicken legs) by using various processing methods. Methods. Comprehensive standard and recognized methods for determining the physical, chemical and mechanical properties of meat products. Results. A study was carried out of the chemical composition of chicken legs in comparison with mechanically deboned poultry meat and grade II beef. The results of the study indicate the possibility of using this raw material as an integral part of the formulations of meat products. Studies were carried out on two groups of samples – collagen-containing ground meat and collagen-containing gel; the results of the collagen content in the samples for different periods of cooking time practically do not change, which confirms the possibility of using collagen-containing products as stabilizers of meat systems in the production of meat products. Collagen-containing ground meat and collagen-containing gel in an amount of 20% in minced chicken meat influences the quality parameters of the finished products. This is confirmed by the results of measuring shear force, critical shear stress, elasticity and consistency of the products. It can be concluded that the use of chicken legs for the production of meat products is possible only with their preliminary processing, namely the separation of flesh tissues from the bones. The method of obtaining these products determines the directions for further their use. Scope of results. Enterprises for processing poultry and producing meat products.

Comparative Cell Wall Polysaccharide Analyses and Transcriptome Profiling during Fruit Ripening Reveal the Molecular Basis of Mealiness in Peach

Mealy peaches are dry and flavorless, which reduces their consumer acceptance. A deeper understanding of the mechanism underlying mealiness is crucial to enhancing peach fruit quality. In this study, comparative profiling was conducted on CP13, CP14, CM, and RM peaches. Sensory evaluation indicated that CP13 and CM are non-mealy clingstone and freestone peaches, respectively, and CP14 and RM are mealy freestone peaches. Both CP13 and CP14, identified as stony hard (SH) peaches, exhibited minimal ethylene release, whereas CM and RM, identified as melting flesh (MF) peaches, released high amounts of ethylene during the ripening process. Scanning electron microscopy (SEM) microstructure observation indicated that cells in the flesh tissue of mealy peaches, CP14 (SH) and RM (MF), were intact and separated, with large intercellular spaces and irregular arrangements. The main factor that promotes mealiness is differences in pectin metabolism, which impact cell wall composition. The fluctuations in polygalacturonase (PG) and pectin methylesterase (PME) activity between mealy and non-mealy peaches were the main factor contributing to mealiness. However, the changes in cell wall metabolism that caused these fluctuations did not have a clear direction. Using transcriptome analysis and weighted gene co-expression network analysis (WGCNA), we were able to identify forty differentially expressed genes (DEGs) that are associated with mealy patterns. Among these DEGs, genes encoding PG were significantly upregulated in mealy peaches (CP14 and RM) compared to non-mealy peaches (CP13 and CM). PpPG1 was the main effector gene for mealiness, while PpPG2, PpEGase2, PpEXP1, PpEXP3, PpAGP2, PpIAA4, and PpABA2 were identified as candidate genes regulating peach mealiness. These findings provide a solid experimental basis for understanding the textual distinctions between mealy and non-mealy peaches.

Influence of Grape Flesh on the Retention and Composition of Polyphenols from Skins and Seeds.

This study examined the impact of grape flesh polysaccharide, protein, and amino acid contents on polyphenol retention from skins and seeds in Pinot noir (Vitis vinifera) and cold-hardy interspecific cultivars Marquette and Frontenac (Vitis spp.). After isolating grape tissues (skin, seed, and flesh), they were soaked either individually or combined with other tissues in a wine-like solution for up to 7 days. Findings revealed that flesh significantly reduces the concentration of condensed tannin, and mono- and diglucoside forms of anthocyanins in the supernatants, due to its rich content in polysaccharides and proteins. Frontenac skin and flesh tissues were the main sources of soluble proteins, amino acids, and soluble polysaccharides. Surprisingly, Marquette exhibited a higher retention of skin tannin than Pinot noir, likely due to its smaller tannin molecular mass, and a potential competitive effect with anthocyanins for the binding sites of flesh.

Genome-Wide Identification and Expression Analysis of Fifteen Gene Families Involved in Anthocyanin Synthesis in Pear

Anthocyanins play a crucial role in imparting red coloration to pear fruits. However, the specific number and expression patterns of each member within the anthocyanin biosynthesis-related gene families in pears require systematic exploration. In this study, based on the pear genome we identified 15 gene families involved in the anthocyanin biosynthesis pathway using the BLASTP and Hidden Markov Model search methods, comprising a total of 94 enzyme genes. Through phylogenetic analysis, conserved domains, motif, and gene structure analysis, these gene families were further categorized into eight distinct lineages. Subsequent collinearity analysis revealed that the expansion of anthocyanin synthesis-related gene families primarily originated from segmental duplications. Analysis of cis-element in the promoter regions of genes related to anthocyanin synthesis unveiled the presence of light-responsive elements and various hormone-responsive elements. This suggests that changes in light stimulation and hormone levels may influence anthocyanin synthesis. RNA-Seq and qRT-PCR analyses indicated differential expression of anthocyanin biosynthesis-related genes between the peel and flesh tissues. During the accumulation of anthocyanins in red-fleshed pears, upstream genes in the anthocyanin biosynthesis pathway such as PbrPAL2, PbrC4H2, PbrC4H3, Pbr4CL2, Pbr4CL17, PbrF3H5, and PbrF3H6 exhibited high expression levels, likely contributing significantly to the red coloration of pear flesh. In summary, we have identified the number of gene family members involved in pear anthocyanin biosynthesis and analyzed the expression patterns of the genes related to pear anthocyanin biosynthesis. These findings provide a solid foundation for further research on the regulatory mechanisms underlying pear anthocyanin biosynthesis and the breeding of red pear varieties.

Cytological characteristics of blueberry fruit development

Using the blueberry cultivar "Powderblue" after pollination, fruits at different developmental stages were collected for study. The transverse and longitudinal diameters, individual fruit weight, and fruit water content were measured during their development. Employing tissue sectioning and microscopy techniques, we systematically studied the morphological features and anatomical structures of the fruits and seeds at various developmental stages, aiming to elucidate the cytological patterns during blueberry fruit development. The results of our study revealed that the "Powderblue" blueberry fruit growth and development followed a double "S" curve. Mature "Powderblue" blueberries were blue-black in color, elliptical in shape, with five locules, an inferior ovary, and an average fruit weight of 1.73 ± 0.17 g, and a moisture content of 78.865 ± 0.9%. Blueberry fruit flesh cells were densely arranged with no apparent intercellular spaces, and mesocarp cells accounted for 52.06 ± 7.4% of fruit cells. In the early fruit development stages, the fruit flesh cells were rapidly dividing, significantly increasing in number but without greatly affecting the fruit's morphological characteristics. During the later stages of fruit development, the expansion of the fruit flesh cells became prominent, resulting in a noticeable increase in the fruit's dimensions. Except for the epidermal cells, cells in all fruit tissues showed varying degrees of rupture as fruit development progressed, with the extent of cell rupture increasing, becoming increasingly apparent as the fruit gradually softened. Additionally, numerous brachysclereids (stone cells) appeared in the fruit flesh cells. Stone cells are mostly present individually in the fruit flesh tissue, while in the placental tissue, they often group together. The "Powderblue" blueberry seeds were light brown, 4.13 ± 0.42 mm long, 2.2 ± 0.14 mm wide, with each fruit containing 50–60 seeds. The "Powderblue" seeds mainly consisted of the seed coat, endosperm, and embryo. The embryo was located at the chalazal end in the center of the endosperm and was spatially separated. The endosperm, occupying the vast majority of the seed volume, comprised both the chalazal and outer endosperm, and the endosperm developed and matured before the embryo. As the seed developed, the seed coat was gradually lignified and consisted of palisade-like stone cells externally and epidermal layer cells internally.

Multiscale Static Compressive Damage Characteristics of Kiwifruit Based on the Finite Element Method.

In the handling or processing process, fruits are easily crushed by external loads. This type of damage in fruit often leads to the internal pulp browning and rotting, with the severity largely dependent on the fruit tissue's geometric and mechanical properties. In kiwifruits, with their thin skin and dark-colored flesh, it is particularly challenging to observe and analyze the damage caused by extrusion through traditional experimental methods. The objective of this research is to construct a multi-scale finite element model encompassing the skin, flesh, and core by measuring the geometric and mechanical properties of kiwifruit, to assess and predict the damage characteristics under compression, and to verify the accuracy of the finite element model through experiments. The results indicated that kiwifruits demonstrated different compressive strengths in different directions during compression. The compressive strength in the axial direction was higher than that in the radial direction, and there was little difference between the long and short radial directions. The flesh tissue is the most vulnerable to mechanical damage under external compression, followed by the core. At strain levels below 5%, there was no noticeable damage in the axial or radial directions of the kiwifruit. However, when strain exceeded 5%, damage began to manifest in some of the flesh tissue. To maintain fruit quality during storage and transportation, the stacking height should not exceed 77 fruits in the axial direction, 48 in the long direction, and 53 in the short direction. The finite element analysis showed that the established model can effectively simulate and predict the internal damage behavior of kiwifruits under compression loads, which is helpful for a deeper understanding of the mechanical properties of fruits and provides a theoretical basis and technical guidance for minimizing mechanical damage during fruit handling.

Determination of Heavy Metals in Etroplus suratensis from Koggala Lagoon in Southern, Sri Lanka

Fish is one of the best organisms in many scientific studies to evaluate heavy metal pollution and human health hazards as they are well-understood organisms in the aquatic environment. The present study was carried out to examine the level of heavy metals in different tissues of Etroplus suratensis (Green chromide) in Koggala lagoon, Sri Lanka. Atomic absorption spectrophotometer (AAS) was used to determine the levels of copper (Cu2+), cadmium (Cd+3), lead (Pb+2) and Chromium (Cr+3) ions in the different tissues (skin, liver, gill, and flesh) of fish belonging to three different sizes; small (7.8-10.2) cm, medium (14.1-16.6) cm, and large (19.8-25.2) cm. The number of thirty-six fish were collected from the lagoon randomly. According to available sizes, 12 fish for each size class were used for the analysis. Furthermore, the histological analysis was carried out to identify the changes at the tissue levelling the gill and liver of fish in three different size classes. Heavy metal concentration in fish samples were compared with the standard levels of heavy metals. Heavy metal concentrations in body tissues of three different body sizes of fish were found to be mainly in the order of Cu>Pb>Cr> Cd. The highest concentrations (P<0.05) of heavy metals were found in the fish flesh and skin, while the lowest concentrations were found in the gills. The range of heavy metal concentrations (g g-1 dry weight) in body tissue of small size, E. suratensis fish were, Cu: 0.0443-0.6210, Cd: 0.0110–0.0214, Pb: Below Detection Level (BDL)- 0.46 and Cr: BDL-39.633, Medium size fish were, Cu: 0.0713–0.6210, Cd: 0.0134-0.0170, Pb: BDL-40.906, Cr: 0.0014–0.0500 and large fish were, Cu: 0.0553–0.345, Cd: 0.0110–0.0256, Pb: 0.0204–0.2103 and Cr: 0.0194–0.0773. However, Cd, Cr and Pb concentrations of flesh tissues were under the standard recommended limits referred by the FAO. Through the Cu concentration in flesh, tissues exceeded the standard limits of FAO. It is not considered as a toxic heavy metal. Histological analysis revealed that the deviation of shape of hepatic cells in the liver may due to the exposure to heavy metals in the lagoon. According to the overall result, biomagnification nature of heavy metals, and the consumption of E. suratensis in the Koggala the bioaccumulation and lagoon may create health hazards to consumers. 
 Keywords: Green chromide, Koggala Lagoon, Heavy metals, Histology

SmuMYB113 is the determinant of fruit color in pepino (Solanum muricatum).

Pepino (Solanum muricatum) is an herbaceous crop phylogenetically related to tomato and potato. Pepino fruit vary in color, size and shape, and are eaten fresh. In this study, we use pepino as a fruit model to understand the transcriptional regulatory mechanisms controlling fruit quality. To identify the key genes involved in anthocyanin biosynthesis in pepino, two genotypes were studied that contrasted in foliar and fruit pigmentation. Anthocyanin profiles were analyzed, as well as the expression of genes that encode enzymes for anthocyanin biosynthesis and transcriptional regulators using both RNA-seq and quantitative PCR. The differential expression of the transcription factor genes R2R3 MYB SmuMYB113 and R3MYB SmuATV suggested their association with purple skin and foliage phenotype. Functional analysis of these genes in both tobacco and pepino showed that SmuMYB113 activates anthocyanins, while SmuATV suppresses anthocyanin accumulation. However, despite elevated expression in all tissues, SmuMYB113 does not significantly elevate flesh pigmentation, suggesting a strong repressive background in fruit flesh tissue. These results will aid understanding of the differential regulation controlling fruit quality aspects between skin and flesh in other fruiting species.

Role of sugar and energy metabolism in apple flesh browning during cold storage

In order to uncover the roles of soluble sugars and energy levels in the flesh browning of apple fruit during refrigeration, the differences of sugar and energy metabolism among the normal flesh tissue of normal fruit (Control) and the normal (FN) and browning (FB) tissue of browning fruit were investigated. Results revealed that the FB tissue exhibited the lowest levels of fructose, glucose, and sucrose. The activities of acid/neutral/cell wall invertase and their transcriptional levels were highest in FB tissue, while sucrose synthase and sucrose phosphate synthase have the opposite. Moreover, succinic dehydrogenase, cytochrome-c oxidase, H+-and Ca2+-ATPase activities were down-regulated in the FB tissue, resulting in the lowest levels of energy charge, adenosine triphosphate, and adenosine diphosphate compared with the non-browning tissues. These findings suggest that the browning of apple flesh during cold storage is associated with a decrease in soluble sugars and energy levels.

Quality maintenance mechanism of oxalic acid treatment in fresh-cut apple fruit during storage based on nontarget metabolomics analysis

A complicated storage reaction mechanism will occur during the storage period in fresh-cut apples, and oxalic acid could physiologically modify the flesh tissue to achieve preservation purposes. This study revealed the storage quality regulation mechanism treated with oxalic acid (3 mmol⋅L−1) in fresh-cut apples through nontarget metabolomics and physiological analyses. It was discovered that oxalic acid could enhance the antioxidant enzymes activities, i.e. superoxide dismutase, catalase, glutathione reductase, etc., contents of soluble solids, total phenolic and reducing sugar, postpone the enhancement of hydrogen peroxide and superoxide anion, and defer the decrease of titratable acid, hardness and total antioxidant capacity. 427 differentially expressed metabolites were identified by nontarget metabolomics. Among them, mainly involved in glycerol ester metabolism, phenylalanine metabolism, starch and sucrose metabolism, etc. were up-regulated treated with oxalic acid. In summary, oxalic acid could enhance the antioxidant properties and regulate metabolite synthesis, leading to delayed quality deterioration of fresh-cut apples.

Comparative transcriptomic and plastid development analysis sheds light on the differential carotenoid accumulation in kiwifruit flesh.

Carotenoids are colorful lipophilic isoprenoids synthesized in all photosynthetic organisms which play roles in plant growth and development and provide numerous health benefits in the human diet (precursor of Vitamin A). The commercially popular kiwifruits are golden yellow-fleshed (Actinidia chinensis) and green fleshed (A. deliciosa) cultivars which have a high carotenoid concentration. Understanding the molecular mechanisms controlling the synthesis and sequestration of carotenoids in Actinidia species is key to increasing nutritional value of this crop via breeding. In this study we analyzed fruit with varying flesh color from three Actinidia species; orange-fleshed A. valvata (OF), yellow-fleshed A. polygama (YF) and green-fleshed A. arguta (GF). Microscopic analysis revealed that carotenoids accumulated in a crystalline form in YF and OF chromoplasts, with the size of crystals being bigger in OF compared to YF, which also contained globular substructures in the chromoplast. Metabolic profiles were investigated using ultra-performance liquid chromatography (UPLC), which showed that β-carotene was the predominant carotenoid in the OF and YF species, while lutein was the dominant carotenoid in the GF species. Global changes in gene expression were studied between OF and GF (both tetraploid) species using RNA-sequencing which showed higher expression levels of upstream carotenoid biosynthesis-related genes such as DXS, PSY, GGPPS, PDS, ZISO, and ZDS in OF species compared to GF. However, low expression of downstream pathway genes was observed in both species. Pathway regulatory genes (OR and OR-L), plastid morphology related genes (FIBRILLIN), chlorophyll degradation genes (SGR, SGR-L, RCCR, and NYC1) were upregulated in OF species compared to GF. This suggests chlorophyll degradation (primarily in the initial ripening stages) is accompanied by increased carotenoid production and localization in orange flesh tissue, a contrast from green flesh tissue. These results suggest a coordinated change in the carotenoid pathway, as well as changes in plastid type, are responsible for an orange phenotype in certain kiwifruit species.

Optical properties and Monte Carlo multi-layered simulation of potato skin and flesh tissues

The study of optical properties of potato plays an essential role in optimizing the application of visible near-infrared (VIS-NIR) spectroscopy for nondestructive testing. This study aimed to investigate the propagation pattern of light in potato tissues and determine the depth of light penetration via a five-layer Monte Carlo simulation. A VIS-NIR integrating sphere system was used to measure the reflectance and transmittance of potato tissues in the range of 550 – 1850 nm. The absorption coefficient μa and the reduced scattering coefficient μ's were calculated using the inverse adding-doubling (IAD) method. The results demonstrated that the difference in μa between the potato skin and flesh tissues was not significant, whereas the difference in μ's was significant. The different microstructures of the potato skin and flesh tissues led to the significant difference in μ's. The results of Monte Carlo multi-layered simulations revealed that light had low reflectivity, high absorbance, and zero transmittance when propagating through the five-layer potato tissue. The wavelengths with highest and lowest absorbance were found to be 1451 and 891 nm, respectively. According to convolution (CONV) calculation results, the penetration depth of light in potato tissue was about 5.5 – 10.6 mm and the diffusion radius was 6.64 – 8.68 mm. This study provided a more accurate and usable sampling area for reflectance measurements using VIS-NIR spectroscopy. The findings of this study provided a reference for more refined non-destructive testing methods for potatoes.

Mineral and Metabolome Analyses Provide Insights into the Cork Spot Disorder on ‘Akizuki’ Pear Fruit

Cork spot is a common physiological disorder in pear fruits, which has been found in some pear cultivars. Mineral nutrition imbalance in fruit is regarded as the principal influence factor for disorder incidence, with some ongoing confusion and controversy. In our research, we explored the cork spot characteristics in Japanese pear ‘Akizuki’ (Pyrus pyrifolia Nakai), adopted metabolome and mineral content analysis for healthy and disordered fruits, and made a correlation analysis of mineral and metabolites. Cork spots are mainly distributed on the outer flesh beneath the fruit peel. In cork spotted tissues, superoxide (SOD) and peroxidase (POD) activities, as well as malondialdehyde (MDA) content, increased. A total of 1024 known metabolites were identified from all the samples and more changes in metabolism were detected between normal and cork spotted flesh tissues. Correlation analysis displayed that Ca, especially the Mg/Ca in fruits, could be used to predict whether an orchard will develop cork spot disorder; Mg and B were associated with the appearance of symptoms, and the contents of Zn, Fe, and Mg, as well as Mg/B and Zn/B, might be strongly tied to the formation of cork spots in pears. This research provides insights into the occurrence of pear cork spot disorder and clarifies the role of minerals.

Stone fruit phenolic and triterpenoid compounds modulate gene expression of Monilinia spp. in culture media

Phenolic and triterpenoid compounds are essential components in stone fruit skin and flesh tissues. They are thought to possess general antimicrobial activity. However, regarding brown rot disease, investigations were only confined to a limited number of phenolics, especially chlorogenic acid. The activity of triterpenoids against Monilinia spp., as an essential part of the peach cuticular wax, has not been studied before. In this work, the anti-fungal effect of some phenolics, triterpenoids, and fruit surface compound (FSC) extracts of peach fruit at two developmental stages were investigated on Monilinia fructicola and Monilinia laxa characteristics during in vitro growth. A new procedure for assaying anti-fungal activity of triterpenoids, which are notoriously difficult to assess in vitro because of their hydrophobicity, has been developed. Measurements of colony diameter, sporulation, and germination of second-generation conidia were recorded. Furthermore, the expression of twelve genes of M. fructicola associated with germination and/or appressorium formation and virulence-related genes was studied relative to the presence of the compounds. The study revealed that certain phenolics and triterpenoids showed modest anti-fungal activity while dramatically modulating gene expression in mycelium of M. fructicola on culture medium. MfRGAE1 gene was overexpressed by chlorogenic and ferulic acids and MfCUT1 by betulinic acid, at 4- and 7- days of mycelium incubation. The stage II FSC extract, corresponding to the period when the fruit is resistant to Monilinia spp., considerably up-regulated the MfLAE1 gene. These findings effectively contribute to the knowledge of biochemical compounds effects on fungi on in vitro conditions.

Comparative study of expression patterns of aquaporin (AQP) genes in apple fruits with contrasting ripening behavior

This research compared expression patterns of aquaporin (AQP) genes in two apple cultivars that exhibit contrasting ripening behavior. Commercially-mature apple fruits of cultivars ‘Golden Delicious’ and ‘Red Fuji’ were chosen as materials. The results showed that compared with ‘Red Fuji’, ‘Golden Delicious’ generally had higher rate of respiration, ethylene production, weight loss, dry matter concentration (DMC), titratable acidity (TA), total soluble solids (TSS) and soluble sugar contents during ripening. At 35 d, cells in ‘Golden Delicious’ were loosely arranged with larger intercellular space, while in ‘Red Fuji’, cells were still densely packed. A total of 20 AQPs were detected in both cultivars. Expression of these identified genes was in a tissue- and cultivar-specific manner during ripening. Generally, expression of MdAQPs was differentially induced at climacteric stage in peel and flesh tissues of ‘Golden Delicious’. In contrast, expression of most MdAQPs was differentially up-regulated at preclimacteric stage in peel and flesh tissues of ‘Red Fuji’. These results will be useful for further study the relationships between MdAQPs and storability of different apple cultivars.

PpHY5 is involved in anthocyanin coloration in the peach flesh surrounding the stone.

Red coloration around the stone (Cs) is an important trait of canned peaches (Prunus persica). In this study, an elongated hypocotyl 5 gene in peach termed PpHY5 was identified to participate in the regulation of the Cs trait. The E3 ubiquitin ligase PpCOP1 was expressed in the flesh around the stone and could interact with PpHY5. Although HY5 is known to be degraded by COP1 in darkness, the PpHY5 gene was activated in the flesh tissue surrounding the stone at the ripening stages and its expression was consistent with anthocyanin accumulation. PpHY5 was able to promote the transcription of PpMYB10.1 through interacting with its partner PpBBX10. Silencing of PpHY5 in the flesh around the stone caused a reduction in anthocyanin pigmentation, while transient overexpression of PpHY5 and PpBBX10 resulted in anthocyanin accumulation in peach fruits. Moreover, transgenic Arabidopsis seedlings overexpressing PpHY5 showed increased anthocyanin accumulation in leaves. Our results improve our understanding of the mechanisms of anthocyanin coloration in plants.

Internal Flesh Browning in Apple and Its Predisposing Factors—A Review

This review article is focused on internal flesh browning (IFB)-related physiological disorders affecting apple (Malus domestica Borkh.) fruit. The expression of different physiological and metabolic IFB-related disorders during post-harvest storage are investigated along with the pre-harvest factors contributing to development. The effectiveness of commercially available pre-harvest technologies for preventing IFB-related disorders are also examined. Internal flesh browning-related disorders are erratic and devastating disorders that result in post-harvest deterioration of fruit quality in apples. Internal flesh browning-related disorders can result in severe economic losses to the apple industry through reduced consumer trust and market acceptability of susceptible cultivars. There are several IFB-related disorders and incidence can range from 0 to 100% of a crop, with severity ranging from no brown flesh to browning of the entire fruit flesh. While IFB-related disorders are found in several apple cultivars, some cultivars are more prone than others. The development of IFB-related disorders involve complex mechanisms depending upon the different types and causes, or factors involved in loss of structural integrity and functional stability of the cell membranes and cell components. Membrane disruption followed by enzymatic oxidation of fruit phenolic compounds by polyphenol oxidases and the production of brown polymers is considered to be the general underlying mechanism causing the browning of flesh tissue. It can be observed in different patterns based on the injured portion of the fruit flesh and the cause of membrane disruption. Three broad categories of IFB-related disorders, including chilling injury, internal CO2 injury, and senescent-related browning disorders, are discussed along with their sub-types. The development of IFB-related disorders can be influenced by both pre-harvest factors and post-harvest conditions and their interactions. Although commonly associated with storage, IFB can also be found immediately after harvest and sometimes in unharvested fruit prior to full maturity. As pre-harvest conditions are a strong contributor to IFB-related disorders, the influence of several pre-harvest orchard conditions, including fruit size, crop load, maturity at harvest, cultivar, climatic conditions, seasonal temperatures, growing degree days, and major mineral nutrients, such as nitrogen (N), phosphorus (P), potassium (K), and calcium (Ca) are reported. Although there are contradictory findings in the studies reported, in general, factors such as larger fruit size, light crop load and delayed harvesting, along with cool temperatures after bloom and warmer temperatures before harvest, increase the risk of IFB-related disorders. In relation to fruit mineral concentrations, high N and low Ca have been associated with increasing IFB, while there is conflicting evidence in relation to the impact of both P and K. This review also examines the effectiveness of commercial pre-harvest technologies such as 1-methylcyclopropene, aminoethoxyvinylglycine and diphenylamine in the prevention of IFB-related disorders, but none of these technologies were found promising due to varied and contradictory results.

Melatonin Treatments Reduce Chilling Injury and Delay Ripening, Leading to Maintenance of Quality in Cherimoya Fruit

Spain is the world's leading producer of cherimoya, a climacteric fruit highly appreciated by consumers. However, this fruit species is very sensitive to chilling injury (CI), which limits its storage. In the present experiments, the effects of melatonin applied as dipping treatment on cherimoya fruit CI, postharvest ripening and quality properties were evaluated during storage at 7 °C + 2 days at 20 °C. The results showed that melatonin treatments (0.01, 0.05, 0.1 mM) delayed CI, ion leakage, chlorophyll losses and the increases in total phenolic content and hydrophilic and lipophilic antioxidant activities in cherimoya peel for 2 weeks with respect to controls. In addition, the increases in total soluble solids and titratable acidity in flesh tissue were also delayed in melatonin-treated fruit, and there was also reduced firmness loss compared with the control, the highest effects being found for the 0.05 mM dose. This treatment led to maintenance of fruit quality traits and to increases in the storage time up to 21 days, 14 days more than the control fruit. Thus, melatonin treatment, especially at 0.05 mM concentration, could be a useful tool to decrease CI damage in cherimoya fruit, with additional effects on retarding postharvest ripening and senescence processes and on maintaining quality parameters. These effects were attributed to a delay in the climacteric ethylene production, which was delayed for 1, 2 and 3 weeks for 0.01, 0.1 and 0.05 mM doses, respectively. However, the effects of melatonin on gene expression and the activity of the enzymes involved in ethylene production deserves further research.

Characterization of Potato Tuber Tissues Using Spatialized MRI T2 Relaxometry.

Magnetic Resonance Imaging is a powerful non-destructive tool in the study of plant tissues. For potato tubers, it greatly assists the study of tissue defects and tissue evolution during storage. This paper describes the MRI analysis of potato tubers with internal defects in their flesh tissue at eight sampling dates from 14 to 33 weeks after harvest. Spatialized multi-exponential T2 relaxometry was used to generate bi-exponential T2 maps, coupled with a classification scheme to identify the different T2 homogeneous zones within the tubers. Six classes with statistically different relaxation parameters were identified at each sampling date, allowing the defects and the pith and cortex tissues to be detected. A further distinction could be made between three constitutive elements within the flesh, revealing the heterogeneity of this particular tissue. Relaxation parameters for each class and their evolution during storage were successfully analyzed. The work demonstrated the value of MRI for detailed non-invasive plant tissue characterization.

Gene expression profiling in Rosa roxburghii fruit and overexpressing RrGGP2 in tobacco and tomato indicates the key control point of AsA biosynthesis.

Rosa roxburghii Tratt. is an important commercial horticultural crop endemic to China, which is recognized for its extremely high content of L-ascorbic acid (AsA). To understand the mechanisms underlying AsA overproduction in fruit of R. roxburghii, content levels, accumulation rate, and the expression of genes putatively in the biosynthesis of AsA during fruit development have been characterized. The content of AsA increased with fruit weight during development, and AsA accumulation rate was found to be highest between 60 and 90 days after anthesis (DAA), with approximately 60% of the total amount being accumulated during this period. In vitro incubating analysis of 70DAA fruit flesh tissues confirmed that AsA was synthesized mainly via the L-galactose pathway although L-Gulono-1, 4-lactone was also an effective precursor elevating AsA biosynthesis. Furthermore, in transcript level, AsA content was significantly associated with GDP-L-galactose phosphorylase (RrGGP2) gene expression. Virus-induced RrGGP2 silencing reduced the AsA content in R. roxburghii fruit by 28.9%. Overexpressing RrGGP2 increased AsA content by 8-12-fold in tobacco leaves and 2.33-3.11-fold in tomato fruit, respectively, and it showed enhanced resistance to oxidative stress caused by paraquat in transformed tobacco. These results further justified the importance of RrGGP2 as a major control step to AsA biosynthesis in R. roxburghii fruit.