Role In Fruit Quality Research Articles

Exogenous application of sucrose promotes the repartitioning of anthocyanin and proanthocyanidin in ‘Cabernet Sauvignon’ grapevine berries

Sugar and its metabolism play a critical role in fruit quality and determine the accumulation characteristics of secondary metabolites. In this study, the dynamic changes in anthocyanin and proanthocyanidin (PA) accumulation during exogenous sugar application were investigated throughout the grape ripening stage, and the underlying biosynthesis mechanism was monitored. Results showed that exogenous sucrose and N-acetyl-d-glucosamine (hexokinase inhibitor, HI) promoted grape berry ripening. Exogenous application of sucrose and HI significantly increased the levels of soluble sugars and anthocyanins, while significantly decreased the levels of acids and PAs in grape berries. Exogenous sucrose and HI activated the transcription of the VvSPS, VvAI and VvNI genes but inhibited the transcription of VvHXK gene to alter sugar metabolism. Notably, the accumulation of anthocyanin compounds, particularly peonidin derivatives, significantly increased in the sucrose- and HI-treated berries by upregulating the transcription of anthocyanin biosynthesis genes, including VvCHS2, VvF3′H, VvDFR, VvLDOX, and VvUFGT, whereas the accumulation of PA units, such as (‒)-epicatechin, (+)-gallocatechin, and (‒)-epigallocatechin, was repressed by downregulating the transcription of the VvLAR2 and VvANR genes, which boosted anthocyanin and PA reprogramming. These results provide preliminary information on how to modulate the biosynthesis and accumulation of anthocyanins and PAs in grape berries by the exogenous application of sucrose and thus, to modify berry composition.

Fungal Mycobiome of Mature Strawberry Fruits (Fragaria x ananassa Variety 'Monterey') Suggests a Potential Market Site Contamination with Harmful Yeasts.

An amplicon metagenomic approach based on the ITS2 region of fungal rDNA was used to investigate the diversity of fungi associated with mature strawberries collected from a volcanic orchard and open-air market stands. Based on the Kruskal-Wallis test, no statistically significant differences were observed in both non-phylogenetic and phylogenetic alpha diversity indices. According to beta diversity analyses, significant differences in fungal communities were found between groups (orchard vs. market). Taxonomic assignment of amplicon sequence variables (ASVs) revealed 7 phyla and 31 classes. The prevalent fungal phyla were Basidiomycota (29.59-84.58%), Ascomycota (15.33-70.40%), and Fungi-phy-Insertae-sedis (0.45-2.89%). The most predominant classes among the groups were Saccharomycetes in the market group, and Microbotryomycetes and Tremellomycetes in the orchard group. Based on the analysis of microbiome composition (ANCOM), we found that the most differentially fungal genera were Hanseniaspora, Kurtzmaniella, and Phyllozyma. Endophytic yeasts Curvibasidium cygneicollum were prevalent in both groups, while Candida railenensis was detected in fruits originating only from the market. In addition, Rhodotorula graminis (relative abundance varying from 1.7% to 21.18%) and Papiliotrema flavescens (relative abundance varying from 1.58% to 16.55%) were detected in all samples regardless of origin, while Debaryomyces prosopidis was detected in samples from the market only, their relative abundance varying with the sample (from 0.80% to 19.23%). Their role in fruit quality and safety has not been yet documented. Moreover, several clinically related yeasts, such as Meyerozyma guilliermondii and Candida parapsilosis, were detected in samples only from the market. Understanding the variety and makeup of the mycobiome in ripe fruits during the transition from the orchard to the market is crucial for fruit safety after harvest.

Phytochemicals and Aroma Compounds Content of Crabapple (Malus tribolata C.K. Schneid.) Genotypes in Kahramanmaraş Province

Crabapple (Malus tribolata C.K. Schneid.), which one of the rare wild fruit trees in Turkey. This study was carried out to determine the aroma compounds, phenolic compound, antioxidant capacity and some fruit properties of fruits obtained from 2 different crabapple genotypes. The amount of phenolic substance was done by Folin-Ciocalteu method; antioxidant analysis was done using DPPH technique. With respect to antioxidant capacities, the highest value (70.12%) was determined in 46 EL 01 genotype. We found that 46 EL 01 genotype had the highest total phenolic content (839.13 mg/100 g). Determination of volatile compounds that play a major role in fruit quality using the HS-SPME/GC/MS technique, total of 37 aroma compound, namely 7 alcohols, 2 terpenes, 5 aldehydes, 17 esters, 1 ketone, 3 acids and 2 other compounds, were found in two different crabapple genotypes. Total aroma compounds in 46 EL 01 and 46 EL 02 genotypes were calculated as 101.78 μg/L and 102.26 μg/L, respectively. As a result, it has been determined that crabapple, which is a wild fruit, has high phenolic and antioxidant contents and also has many aroma compounds.

Sugar Signaling During Fruit Ripening.

Sugars play a key role in fruit quality, as they directly influence taste, and thus consumer acceptance. Carbohydrates are the main resources needed by the plant for carbon and energy supply and have been suggested to be involved in all the important developmental processes, including embryogenesis, seed germination, stress responses, and vegetative and reproductive growth. Recently, considerable progresses have been made in understanding regulation of fruit ripening mechanisms, based on the role of ethylene, auxins, abscisic acid, gibberellins, or jasmonic acid, in both climacteric and non-climacteric fruits. However, the role of sugar and its associated molecular network with hormones in the control of fruit development and ripening is still poorly understood. In this review, we focus on sugar signaling mechanisms described up to date in fruits, describing their involvement in ripening-associated processes, such as pigments accumulation, and their association with hormone transduction pathways, as well as their role in stress-related responses.

Identification and expression profiling of sugar transporter genes during sugar accumulation at different stages of fruit development in apricot.

Sugars are considered as an essential signaling molecule for fruit growth and development, which plays a key role in fruit quality. Up to now, the mechanism controlling sugar metabolism and transport in apricot is unclear. Therefore, in the present study, we measured sugar contents at six different stages of fruit development and ripening, and significant variations were observed throughout these stages. The concentration of glucose and fructose first decreased then increased, sucrose concentration first increased then decreased, while the concentration of sorbitol gradually decreased from growth to maturity. Furthermore, thirty sugar transporter genes related to sucrose synthesis and transport were identified and categorized into different subfamilies based on the phylogenetic analysis. The result of cis-regulatory components showed that under different plant hormones, biotic and abiotic stresses, few elements could be regulated. The correlation analysis showed a higher relationship between ParSuSy5, ParSuSy6, ParSuSy7, and ParFK1 genes and sugar contents, indicating that these genes might have a key role in sugar accumulation and fruit quality. In general, these findings will provide a deep understanding of genomic information and expression profiles of sugar transporter genes, which will contribute toward improvement in fruit quality of apricot.

NMR-based fruit metabonomic analysis of watermelon grafted onto different rootstocks under two potassium levels

Grafting watermelon onto nonself-rootstock is an effective way to solve the soilborne disease, and potassium plays an important role in fruit quality; however, a comprehensive metabonomic analysis of rootstock on the fruit quality of watermelon under different potassium levels is lacking. In this study, the NMR-based metabonomic approaches was used to reveal the effects of nonself-rootstocks (wild watermelon, bottle gourd, pumpkin) on the fruit metabolites accumulation of watermelon under two potassium levels (normal potassium: 6.0 mM K, low potassium: 0.1 mM K) at ripening stage. Thirty eight metabolites were identified, including nineteen amino acids and ammonium compounds, four organic acids, six sugars, four nucleic acid and five other compounds. Compared with self-grafted plants, nonself-rootstock grafting significantly increased the concentrations of some health-related compounds in watermelon fruit under normal potassium, such as citrulline, methionine, isoleucine, phenylalanine, leucine and valine. Low potassium decreased sucrose concentration, but increased the concentrations of some important fruit metabolites, including citrulline and glucose in watermelon fruit. Nonself-rootstock grafting increased the sucrose and citrulline concentrations under low potassium. Our results suggested that the accumulation of some fruit quality-related compounds in watermelon can be enhanced by grafting onto nonself-rootstocks under both normal and low potassium conditions.

Expression patterns of genes involved in sugar metabolism and accumulation during peach fruit development and ripening

In fleshy fruits, sugars (glucose, fructose, sucrose and sorbitol) are most important for fruit growth and development but also play a central role in fruit quality. In Peach (Prunus persica), we observed the sugars content at six developmental stages through high pressure liquid chromatography (HPLC). There was variation during fruit development and ripening, sucrose first increased then decreased; glucose and fructose first decreased, and then increased while sorbitol always decreased. In past, understanding about the mechanisms which control the sugar metabolism and accumulation in peach remains quite limited. We studied the transcript profiles of total 30 genes encoding key enzymes and transporters, which were involved in sucrose metabolism, resynthesis and transport. 13 putative genes including sucrose phosphatase synthase (PpSPS4 and PpSPS2), Hexokinases (PpHK1 and PpHK3), neutral/natural invertase (PpNINV1and PpNINV2), vacuolar acid invertase (PpVAINV2), sucrose transporter (PpSUT2), vacuolar glucose transporters (PpVGT1, PpVGT2 and PpVGT3) and tonoplast monosaccharides transporters (PpTMT1 and PpTMT2) highly expressed during peach fruit ripening. PpSPS4 had significantly positive correlation with glucose and fructose. Our results suggested that more sucrose accumulated in cytosol because of upregulation of (PpSPS4 and PpSPS2), that sucrose imported into vacuole through upregulation of PpSUT2, PpVGT1, PpVGT2, PpVGT3, PpTMT1 and PpTMT2 transporters, where cleaving of sucrose is done by upregulation of PpVAINV2. Hence, level of sucrose decreased as fruit ripe. As a result, the concentration of glucose and fructose increased at ripening stage (S4 II to S4 III). So, these marker genes can be involved in peach fruit ripening. This study will improve our understanding and lay foundation to explore the function of these genes and improvement of peach fruit quality.

Analysis of Volatile Compounds in Pears by HS-SPME-GC×GC-TOFMS.

Aroma plays an important role in fruit quality and varies among different fruit cultivars. In this study, a sensitive and accurate method based on headspace solid-phase microextraction (HS-SPME) coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) was developed to comprehensively compare aroma components of five pear cultivars. In total, 241 volatile compounds were identified and the predominant volatile compounds were esters (101 compounds), followed by alcohols (20 compounds) and aldehydes (28 compounds). The longyuanyangli has the highest relative concentration (838.12 ng/g), while the Packham has the lowest (208.45 ng/g). This study provides a practical method for pear aroma analysis using SPME and GC×GC-TOFMS.

Characterisation of the whole-genome wide hexokinase gene family unravels the functional divergence in pear (Pyrus bretschneideri Rehd.)

ABSTRACTHexokinase genes (HXK) encode enzymes that play an important role in fruit quality and plant development because they participate in the first step of the glycolytic pathway for sugar accumulation and metabolism. In this study, the authors conducted analysis of the phylogeny, gene structure, and expression of HXK genes in pear (Pyrus bretschneideri Rehd.), comparing them with 7 other plant species. A total of 10 HXK protein sequences from pear and 33 HXKs from 7 other species were identified and clustered into 4 groups, matching their motif classification. Duplication events and motif structure variation attributed the diversification of HXK genes, supported by differential expression pattern of PbrHXKs from pear fruit transcriptome data and qRT – PCR verification. Combining pear fruit soluble sugar content data and analyses above, PbrHXK1and PbrHXK3 were identified as important candidate genes in sorbitol, fructose, and glucose accumulation during pear fruit development. PbrHXK1and PbrHXK3 were identified as important candidate genes in sorbitol, fructose, and glucose accumulation during pear fruit development. Subsequent research on these highly expressed PbrHXKs will benefit the enhancement of sugar content and quality in pear.

Potassium enhances the sugar assimilation in leaves and fruit by regulating the expression of key genes involved in sugar metabolism of Asian pears

Potassium (K) plays an important role in fruit quality, and is well known as the most important quality element. A field experiment was conducted with four K levels of 0 (control), 150 (K150), 300 (K300), 450 (K450) kg K2O ha−1 in 2014–2015. The aim was to elucidate the roles of K in fruit growth, and the mechanism of K in regulating sugar metabolism between the leaves and fruit of Asian pear (Pyrus L.). The results showed that the K concentration and accumulation in leaves and fruit with the net photosynthetic rate and SPAD value of leaves were found to increase with the increase of K application rates. Increasing K application rates also led to promote the effectiveness of accumulation of glucose, fructose, sorbitol, and sucrose in fruit. During the early fruit development stage, the increase of all soluble sugars in leaves was correlated with the up-regulation expression of gene AIV and S6PDH. Furthermore, with fruit development, the expression of AIV1, SPS1 and SUS, S6PDH and SDH3 involved in sugar metabolism in leaves were up-regulated by increasing the K application rates, resulting in higher accumulation of soluble sugars in leaves. Interestingly, at the fruit maturity stage the expression of SUT in leaves, and SPS1, SUS and SUT in fruit was significantly up-regulated, leading to higher sucrose accumulation in fruit. Thus, K-promoted sugar accumulation of the leaves and fruit might result from up-regulated expression levels of key genes involved in sugar metabolism by K in leaves and fruit.

Volatile compounds in the peel and flesh of cucumber (Cucumis sativus L.) grafted onto bottle gourd (Lagenaria siceraria) rootstocks

SummaryThe objective of this study was to investigate the distribution of volatile organic compounds (VOCs) in the peel and flesh of the cucumber (Cucumis sativus L.) cultivar ‘Çengelköy’ grafted onto different bottle gourd rootstocks, as VOCs play an essential role in fruit quality. Three genotypes of bottle gourd (Lagenaria siceraria; ‘33-35’, ‘33-41’ and ‘46-03’) were chosen as being representative of Turkish bottle gourd germplasm. The VOCs in each rootstock-scion combination were analysed using carboxen-divinylbenzene-polydimethylsiloxane fibres for solid-phase micro-extraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The VOCs (Z)-6-nonenol (21.4 – 28.6%), (E,Z)-2,6-nonadienol (3.2 – 13.0%), (E,Z)-3,6-nonadienol (1.9 – 7.1%), 1-nonanol (4.9 – 7.2%), (E)-2-nonenal (3.9 – 6.6%), (E,Z)-2,4-heptadienal (5.7 – 6.9%), (Z)-6-nonenal (3.6 – 5.4%), (E)-2-hexenal (0.9 – 4.4%), (E,E)-3,5-octadien-2-one (3.2 – 3.5%), and hexanal (1.9 – 3.6%) were the most abundant compounds found in cucumber peel. Grafting had a significant (P ≤ 0.05) effect on the percentage composition of the major VOCs in peel. (E,Z)-2,6-Nonadienal (34.3 – 41.5%), (E)-2-nonenal (15.5 – 19.9%), (Z)-6-nonenal (5.9 - 8.0%), (Z,Z)-3,6-nonadienol (2.6 – 8.4%), (Z)-6-nonenol (2.7 – 7.9%), 3-decyne (2.1 – 3.4%), and (E,Z)-2,6-nonadienol (1.9 – 5.7%) were the most significant volatiles in cucumber flesh. Of these compounds, (E,Z)-2,4-heptadienal, (E,E)-3,5-octadien-2-one, and 3-decyne were identified as cucumber VOCs for the first time. The results showed that the percentage composition of VOCs in the peel and flesh of cucumbers grafted onto bottle gourd ‘33-41’ were closest to those in ungrafted control cucumber, ‘Çengelköy’. Therefore, Turkish bottle gourd genotype ‘33-41’ has high potential as a rootstock for cucumer grafting.

RELATIONSHIP BETWEEN INSTRUMENTAL AND SENSORY DETERMINATION OF APPLE AND PEAR TEXTURE

ABSTRACT The relationship between compressive forces, tensile forces and sensory perception of apple and pear texture was evaluated over two harvest years. A trained panel assessed the sensory attribute of apple and pear samples. Compressive forces were determined using a Guss Fruit Texture analyzer and Sinclair iQ™. Tensile determinations were obtained using a unique method employing both tensile and compression elastic modulus of the fruit tissue. Results showed that crispness, hardness and fracturability were significantly correlated (r = 0.80–0.90). Sinclair iQ™ System and Guss Fruit Texture measurements on apple (r = 0.78–0.83) and pears (r = 0.83) showed a significant correlation with sensory results for hardness. Tensile determinations predicted crispness in apples (r = 0.88) and pears (r = 0.85). A combination method of compressive and tensile determinations may offer the most accurate prediction of textural properties of apples and pears.PRACTICAL APPLICATIONSApple and pear firmness is a primary measure of fresh quality. With apples and pears being such an important commodity in Washington State and firmness playing such an important role in fruit quality, more knowledge about tissue mechanics and its correlation with human perception is important for further development of the apple and pear industry. In response to the need to develop an instrumental determination of texture with a strong correlation to sensory evaluation, a new methodology was developed whereby the tensile properties of apples and pears were measured.

Effect of tomato pleiotropic ripening mutations on flavour volatile biosynthesis

Ripening is a tightly controlled and developmentally regulated process involving networks of genes, and metabolites that result in dramatic changes in fruit colour, texture and flavour. Molecular and genetic analysis in tomato has revealed a series of regulatory genes involved in fruit development and ripening, including MADS box and SPB box transcription factors and genes involved in ethylene synthesis, signalling and response. Volatile metabolites represent a significant part of the plant metabolome, playing an important role in plant signalling, defence strategies and probably in regulatory mechanisms. They also play an important role in fruit quality. In order to acquire a better insight into the biochemical and genetic control of flavour compound generation and links between these metabolites and the central regulators of ripening, five pleiotropic mutant tomato lines were subjected to volatile metabolite profiling in comparison with wild-type Ailsa Craig. One hundred and seventeen volatile compounds were identified and quantified using SPME (Solid Phase Microextraction) headspace extraction followed by Gas Chromatography–Mass Spectrometry (GC–MS) and the data were subjected to multivariate comparative analysis. We find that the different mutants each produce distinct volatile profiles during ripening. Through principal component analysis the volatiles most dramatically affected are those derived from fatty-acids. The results are consistent with the suggestion that specific isoforms of lipoxygenase located in the plastids and the enzymes that provide precursors and downstream metabolites play a key role in determining volatile composition.

ENDOPOLYGALACTURONASE GENOTYPIC VARIATION IN PRUNUS

Softening is an integral component of ripening for most fruit. The cell wall-metabolizing enzyme, endopolygalacturonase (endoPG), is involved in fruit softening of many species. In peach and nectarine (Prunus persica), maximum expression of endoPG coincides with the climacteric peak and period of rapid softening known as the melting phase that is characteristic of most fresh-market cultivars. We previously identified endoPG as the gene controlling the major fruit firmness and texture traits of Melting flesh (M) and Freestone (F) in peach. There appear to be at least two copies of the gene at the same locus, and we hypothesize that one copy controls M and another F, where the three main phenotypes observed are due to major deletions in one or both gene copies. Smaller changes in endoPG are suspected to result in quantitative differences in fruit firmness and texture. Other Prunus fruit crops, such as apricot, plum, and cherry, also have traits resembling M and F, and given the close synteny within Prunus, endoPG may play an important role in fruit quality in each of these crops. Therefore, diverse germplasm was surveyed with PCR tests for endoPG to confirm the role in Prunus fruit softening, and to identify further alleles in cultivated and related wild species that may convey useful new quality characteristics. A microsatellite associated with endoPG was the most polymorphic region of the gene using PCR amplification, allowing a detailed examination of endoPG genotypic diversity in Prunus. Sequence analysis of other parts of the gene is complementing our insights into the diversity and function of this important fruit quality gene.

The role of fruit mineral composition on fruit softness and mesocarp discolouration in ‘Pinkerton’ avocado (Persea americana Mill.)

SummaryThe successful marketing and export of fruit depends, to a large degree, on the predictability and consistency of quality. The ‘Pinkerton’ avocado, however, is prone to a physiological disorder known as “mesocarp discolouration” during and after storage. Furthermore, fruit have been found to arrive at their European destination with variable softness. Mesocarp discolouration was initially thought to be the result of chilling injury, however differences in quality were noted between fruit from different origins. Fruit were subjected to mineral analysis following a suspicion that pre-harvest factors played a role in fruit quality. Excessive nitrogen concentrations were found to have the most significant role in determining the severity of mesocarp discolouration. In addition, decreasing copper, manganese and boron concentrations during the season also appeared to contribute to the development of the disorder. The results of this study indicate that interactions between minerals could be more important in determining quality than evaluating individual elements.

Biochemistry and biological functions of citrus limonoids

Abstract Limonoids are one of bitter principles in citrus juices. Excessive bitterness lowers the quality and value of citrus juices. Nomilin is considered to be the precursor of all other limonoids accumulated in Citrus and related species. It is biosynthesized from acetate via the terpenoid biosynthetic pathway in the phloem region of stems and then translocated to the leaves, fruit tissues, peels, and seeds where it is further metabolized to other limonoids. The citrus limonoid aglycones are then glucosidated by limonoid UDP‐D‐glucose transferase in maturing fruit tissues and seeds. These limonoid glucosides are accumulated in such high concentrations that they are one of major secondary metabolites in citrus fruit tissues, and they play an important role in fruit quality and possibly in human health. Research on creation of transgenic citrus trees that produce fruits free of the limonoid bitterness problem is in progress. Limonoids have been shown to induce glutathione S‐transferase activity and inhib...