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Summary: Tomato (Solanum lycopersicum) stands as one of the most valuable vegetable crops globally, and fruit firmness significantly impacts storage and transportation. To identify genes governing tomato firmness, we scrutinized the firmness of 266 accessions from core collections. Our study pinpointed an ethylene receptor gene, SlEIN4, located on chromosome 4 through a genome‐wide association study (GWAS) of fruit firmness in the 266 tomato core accessions. A single‐nucleotide polymorphism (SNP) (A → G) of SlEIN4 distinguished lower (AA) and higher (GG) fruit firmness genotypes. Through experiments, we observed that overexpression of SlEIN4AA significantly delayed tomato fruit ripening and dramatically reduced fruit firmness at the red ripe stage compared with the control. Conversely, gene editing of SlEIN4AA with CRISPR/Cas9 notably accelerated fruit ripening and significantly increased fruit firmness at the red ripe stage compared with the control. Further investigations revealed that fruit firmness is associated with alterations in the microstructure of the fruit pericarp. Additionally, SlEIN4AA positively regulates pectinase activity. The transient transformation assay verified that the SNP (A → G) on SlEIN4 caused different genetic effects, as overexpression of SlEIN4GG increased fruit firmness. Moreover, SlEIN4 exerts a negative regulatory role in tomato ripening by impacting ethylene evolution through the abundant expression of ethylene pathway regulatory genes. This study presents the first evidence of the role of ethylene receptor genes in regulating fruit firmness. These significant findings will facilitate the effective utilization of firmness and ripening traits in tomato improvement, offering promising opportunities for enhancing tomato storage and transportation capabilities. [ABSTRACT FROM AUTHOR]

Pear (P. communis L.), which is a climacteric fruit species, has a very short storage and shelf life, and significant losses occur due to high metabolic activity and the fruit's respiration rate after harvest. Therefore, preventing or reducing post‐harvest quality losses in pear is one of the most basic problems awaiting solution. In this study, we planned for this purpose; the fruits of the Ankara pear cultivar treated with modified atmosphere packaging (MAP), putrescine (1 mM), and MAP + putrescine were stored for 120 days at 1°C and 90 ± 5% relative humidity. The quality analyses and measurements, such as weight loss, decay rate, fruit firmness, soluble solids content (SSC), titratable acidity (TA), total phenolic compounds, antioxidant capacity, organic acids, and specific phenolic compounds, were performed on the 30th, 60th, 90th, and 120th days. Weight loss and decay ratios were lower for putrescine and putrescine + MAP‐applied fruit. With these applications, the softening of the fruit was slowed down, and the increasing SSC in the fruit and the decreasing TA rates were lower, and thus the ripening of the fruit was delayed. Changes in individual phenolic content and organic acids were lower in MAP and putrescine‐applied fruit. The study revealed that MAP and putrescine applications in pear can be used effectively to maintain fruit quality after harvest. [ABSTRACT FROM AUTHOR]

Fruit softening is a crucial factor that controls shelf life and commercial value. Pectate lyase (PL) has a major role in strawberry fruit softening. However, the PL gene family in strawberry has not been comprehensively analyzed. In this study, 65 FaPL genes were identified in the octoploid strawberry genome. Subcellular localization prediction indicated that FaPLs are mostly localized to the extracellular and cytoplasmic spaces. Duplication event analysis suggested that FaPL gene family expansion is mainly driven by whole genome or segmental duplication. The FaPL family members were classified into six groups according to the phylogenetic analysis. Among them, FaPL1, 3, 5, 20, 25, 42, and 57 had gradually increased expressions during strawberry fruit development and ripening and higher expression levels in the fruits with less firmness than that in firmer fruit. This result suggested that these members are involved in strawberry softening. Furthermore, overexpression of FaPL1 significantly reduced the fruit firmness, ascorbic acid (AsA), and malondialdehyde (MDA) content but obviously increased the anthocyanins, soluble proteins, and titratable acidity (TA), while it had no apparent effects on flavonoids, phenolics, and soluble sugar content. These findings provide basic information on the FaPL gene family for further functional research and indicate that FaPL1 plays a vital role in strawberry fruit softening. [ABSTRACT FROM AUTHOR]

Loquats have drawn much attention due to their essential nutrients and unusual phenology, which fills a market gap in early spring. Fruit firmness (FF) is one of the most important quality attributes. Dynamic changes in FF, cell wall (CW) polysaccharides, CW hydrolase activity, and expression of CW metabolism-related genes during the fruit development and ripening stages of two contrasting loquat cultivars were compared. Although the two cultivars possessed similar FF at the initial fruitlet stage, Dawuxing was significantly firmer than Ninghaibai at all subsequent time points. FF was positively correlated with the contents of covalent-soluble pectin and hemicellulose, activity of peroxidase, and gene expressions of PME, EG, CAD6, and POD; and negatively correlated with the contents of water-soluble pectin, activities of polygalacturonase, endo-glucanase, cellobiohydrolase, and xylanase, and gene expressions of PG, EG2, PAL1, PAL3, and CAD5. Identifying molecular mechanisms underlying the differences in FF is useful for fundamental research and crop improvement in future. [ABSTRACT FROM AUTHOR]

The Cellulose synthase (CesA) and Cellulose synthase-like (Csl) gene superfamilies encode key enzymes involved in the synthesis of cellulose and hemicellulose, which are major components of plant cell walls, and play important roles in the regulation of fruit ripening. However, genome-wide identification and functional analysis of the CesA and Csl gene families in strawberry remain limited. In this study, eight CesA genes and 25 Csl genes were identified in the genome of diploid woodland strawberry (Fragaria vesca). The protein structures, evolutionary relationships, and cis-acting elements of the promoter for each gene were investigated. Transcriptome analysis and quantitative real-time PCR (qRT-PCR) results showed that the transcript levels of many FveCesA and FveCsl genes were significantly decreased during fruit ripening. Moreover, based on the transcriptome analysis, we found that the expression levels of many FveCesA/Csl genes were changed after nordihydroguaiaretic acid (NDGA) treatment. Transient overexpression of FveCesA4 in immature strawberry fruit increased fruit firmness and reduced fresh fruit weight, thereby delaying ripening. In contrast, transient expression of FveCesA4-RNAi resulted in the opposite phenotypes. These findings provide fundamental information on strawberry CesA and Csl genes and may contribute to the elucidation of the molecular mechanism by which FveCesA/Csl-mediated cell wall synthesis regulates fruit ripening. In addition, these results may be useful in strawberry breeding programs focused on the development of new cultivars with increased fruit shelf-life. [ABSTRACT FROM AUTHOR]

Cucumber is an extremely perishable vegetable; however, under room conditions, the fruits become unfit for consumption 2–3 days after harvesting. One natural variant, DC-48 with an extended shelf-life was identified, fruits of which can be stored up to 10–15 days under room temperature. The genes involved in this economically important trait are regulated by non-coding RNAs. The study aims to identify the long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) by taking two contrasting genotypes, DC-48 and DC-83, at two different fruit developmental stages. The upper epidermis of the fruits was collected at 5 days and 10 days after pollination (DAP) for high throughput RNA sequencing. The differential expression analysis was performed to identify differentially expressed (DE) lncRNAs and circRNAs along with the network analysis of lncRNA, miRNA, circRNA, and mRNA interactions. A total of 97 DElncRNAs were identified where 18 were common under both the developmental stages (8 down regulated and 10 upregulated). Based on the back-spliced reads, 238 circRNAs were found to be distributed uniformly throughout the cucumber genomes with the highest numbers (71) in chromosome 4. The majority of the circRNAs (49%) were exonic in origin followed by inter-genic (47%) and intronic (4%) origin. The genes related to fruit firmness, namely, polygalacturonase, expansin, pectate lyase, and xyloglucan glycosyltransferase were present in the target sites and colocalized networks indicating the role of the lncRNA and circRNAs in their regulation. Genes related to fruit ripening, namely, trehalose-6-phosphate synthase, squamosa promoter binding protein, WRKY domain transcription factors, MADS box proteins, abscisic stress ripening inhibitors, and different classes of heat shock proteins (HSPs) were also found to be regulated by the identified lncRNA and circRNAs. Besides, ethylene biosynthesis and chlorophyll metabolisms were also found to be regulated by DElncRNAs and circRNAs. A total of 17 transcripts were also successfully validated through RT PCR data. These results would help the breeders to identify the complex molecular network and regulatory role of the lncRNAs and circRNAs in determining the shelf-life of cucumbers. [ABSTRACT FROM AUTHOR]

Grape softening is a complex process that is related to pectin degradation in the plant cell wall. β-galactosidases (BGALs) can degrade the galactose in rhamnogalacturonan (RG-I) pectin and plays an important role in fruit softening, but the functions of genes encoding BGALs during berry development and softening are still unclear. Fourteen VvBGAL genes were identified in the grape genome. Among them, VvBGAL3 was consistently more highly expressed in grape flesh that was still firm compared to soft grape flesh during berry development. Overexpression of VvBGAL3 increased fruit firmness and decreased the postharvest water loss in transgenic tomato fruits. Histological analysis indicated that pericarp thickness and the number of epidermal cell layers increased, and that there were more vascular sheath cells in the fruit mid-column of transgenic tomato fruits. Yeast one-hybrid and dual-luciferase reporter assays verified that VvNAC1 negatively regulated the transcription of VvBGAL3. In addition, overexpression of VvBGAL3 led to down-regulation of cell wall degradation-related genes at different stages of fruit ripening. Together, these results suggested that VvBGAL3 plays an important role in fruit development, fruit ripening and fruit softening and may serve as a target for future breeding programs. • The BGAL enzyme activities of soft-fleshed 'HXM' were significantly higher than those of the firm-fleshed 'SM' during berry softening. • Overexpression of VvBGAL3 increased fruit firmness and decreased the postharvest water loss in transgenic tomato fruits. • Yeast one-hybrid and dual-luciferase reporter assays verified that VvNAC1 negatively regulated the transcription of VvBGAL3. [ABSTRACT FROM AUTHOR]

Fruit firmness is an important target of melon breeding, as it is associated with shelf life and economic value; however, the precise mechanism that determines fruit firmness during fruit ripening remains elusive. In the present study, one hundred forty-four F2 plants and F2–3 families derived from the high-firmness melon line M2–10 and the low-firmness melon line ZT091 were used to identify major quantitative trait loci by specific-locus amplified fragment sequencing with bulked segregant analysis. Simple sequence repeat (SSR) and cleaved amplified polymorphic sequence (CAPS) markers based on the resequencing of parental lines were also used to narrow the associated region to identify candidate genes. Two regions associated with fruit firmness were investigated, including a 4.87 Mb region on chr. 2 and a 28.7 Mb region on chr. 5 of the melon genome. SSR and CAPS markers were used to construct a genetic map of the associated regions: QTL ff5.1 was located between CmSSR13509 and CmSSR13423 and explained 38.44% of the observed variation, with an LOD threshold of 17.44; ff2.1 was located between CmSSR07709 and SNP22228 and explained 28.14% of the variation, with an LOD threshold of 3.8, and this region included 106 Kb and 10 candidate genes. Quantitative real-time PCR was performed to investigated the investigate candidate gene expression at 15, 20 and 25 days after pollination in the parental lines, and significant expression levels were detected for most of the genes, including four genes of unknown function and MELO3C017519, MELO3C017520, MELO3C017522, MELO3C029506, and MELO3C029520. These results revealed a new QTL, ff2.1, for melon fruit firmness-related gene identification. [ABSTRACT FROM AUTHOR]

Fruit maturation and softening are critical traits that control fruit shelf-life. In the climacteric tomato (Solanum lycopersicum L.) fruit, ethylene plays a key role in fruit ripening and softening. We characterized two related proteins with contrasting impact on ethylene production, ACC oxidase 1 (SlACO1) and SlE8. We found SlACO1 and SlE8 to be highly expressed during fruit ripening. To identify loss-of-function alleles, we analysed the tomato genetic diversity but we did not find any natural mutations impairing the function of these proteins. We also found the two loci evolving under purifying selection. To engineer hypomorphic alleles, we used TILLING (target-induced local lesions in genomes) to screen a tomato ethylmethane sulfonate-mutagenized population. We found 13 mutants that we phenotyped for ethylene production, shelf-life, firmness, conductivity, and soluble solid content in tomato fruits. The data demonstrated that slaco1-1 and slaco1-2 alleles could be used to improve fruit shelf-life, and that sle8-1 and sle8-2 alleles could be used to accelerate ripening. This study highlights further the importance of SlACO1 and SlE8 in ethylene production in tomato fruit and how they might be used for post-harvest fruit preservation or speeding up fruit maturation. [ABSTRACT FROM AUTHOR]

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Pawpaw (Carica pawpaw L.) fruit production and utilisation have been on the increase in Uganda. However, challenges related to identification of phenotypes with inherent characteristics for improvement of fruit shelf life have limited identification of better varieties. The objective of this study was to evaluate the phenotypic diversity and shelf life determinants of Uganda's pawpaw accessions and their variations based on selected quality parameters. Nineteen accessions were collected as seeds from different markets of Uganda, germinated and planted in Namulonge-Wakiso district, central Uganda. The accessions were significantly (P<0.05) variable in terms of fruit weight parameters, with dry matter ranging from 14 - 19% and fruit weight of up to 3.9 kg; while pulp weight was up to 3.2 kg per fruit. Pulp firmness parameters were also significantly variable (P<0.05) and highly correlated with shelf life of the fruit, which ranged from 7 - 13 days depending on the accession. Fruit pulp pH ranged from 4.4-5.6; while titratable acidity of the fruit ranged from 0.03-0.08%. The accessions were clustered in four main clusters depending on the fruit firmness properties, fruit shelf life, fruit weight, pH and titratable acidity as definitive parameters. These accessions were distinguished based on morphological parameters, and henceforth defined for nutritional and economic uses. Accessions with high fruit firmness (>5 kg F) such as 16/20' 16/16, 16/17 and 18/1; and external pulp thickness (>2 cm) such as 16/ 16, 16/17 and 18/1 had improved fruit shelf life and are recommended for marketability and processing. [ABSTRACT FROM AUTHOR]

Summary: The firmness of fleshy fruit crops has a significant effect on their quality, consumer preference, shelf life and transportability. In a combined quantitative trait locus and genome‐wide association studies study of apple fruit texture, we identified a mutation (C‐G) in the ethylene response factor‐associated amphiphilic repression (EAR) motif in the coding region of the apple ETHYLENE RESPONSE FACTOR4 (ERF4) gene. Chromatin immunoprecipitation sequencing showed that ERF4 binds to the promoter of ERF3, which is involved in regulation of ethylene biosynthesis. The EAR mutation in ERF4 results in reduced repression of ERF3 expression, which is turn promotes ethylene production and loss of fruit firmness. ERF4 acts as a transcriptional repressor whose activity is modulated by a TOPLESS co‐repressor 4 (TPL4)‐binding EAR repression motif. Biolayer interferometry analysis showed that the mutation in the EAR motif causes a reduction in the interaction with TPL4. Suppression of ERF4 or TPL4 promoted fruit ripening and ethylene production. Taken together, our results provide insights into how ERF4 allelic variation underlies an important fruit quality trait. Significance Statement: Fruit softening is a hallmark of ripening in apple fruit, but the degree of softening varies among cultivars, with corresponding variation in their quality and consumer preference. Much attention has been paid to the molecular characterization of fruit softening; however, the underlying genetic mechanisms are still not well understood. Here, we show that a mutation in the seqeucene encoding the EAR motif of ERF4 results in a decrease in its repression activity, thereby promoting fruit softening and ripening. [ABSTRACT FROM AUTHOR]

In this research, the effects of pre-harvest 0.25% iron treatments on yield, some fruit quality parameters, biochemical properties and micronutrient content of 'Santa Maria', 'Deveci' and 'Akça' pear cultivars were investigated. Effects of iron treatments on yield were found to be significant. While fruit firmness decreased with iron treatments in 'Santa Maria' and 'Akça' pears, the value increased in 'Deveci' cultivar. Besides, total phenolic compounds and antioxidant activity also decreased with iron treatments. Effects of iron treatments on individual phenolics were not found to be significant. It was concluded that foliar iron treatments had positive effects in all cultivars. [ABSTRACT FROM AUTHOR]

• The silencing of the SlGH9-21 gene increased the drought resistance of tomato. • The silencing of SlGH9-21 gene delayed fruit ripening by about 10 days and significantly enhanced the mechanical hardness of tomato fruits during and after ripening. • The silencing of SlGH9-21 gene may significantly prolong the postharvest storage time of tomato fruits by affecting the mechanical hardness and degradation of cellulose, which is the main component of fruit cell wall. Drought, one of the most important abiotic factors affecting plant growth, causes a large reduction in tomato production every year. Tomato, a berry fruit and vegetable that can be eaten fresh or cooked, has rich nutritional value. However, most of ripe fruits show softening of pericarp, which leads to damage easily during transportation, and shorten the shelf life. Fruit mechanical strength is important to the texture, transport resistance and shelf life of tomato fruit. We found a natural tomato mutant in the field, which showed excellent drought resistance ability and late ripening characteristics. The target gene Solyc09g075360 (SlGH9-21) was obtained through transcriptome data screening. After the gene was silenced, tomatoes improved their drought resistance by reducing stomatal aperture and increasing stem vessel diameter. We also found that silencing of the SlGH9-21 gene delayed the ripening of tomato fruit and improved fruit firmness. Compared with the control, the ripening of the fruit of SlGH9-21 gene-silenced plants was delayed by approximately 10 days, which increased the fruit firmness and storage tolerance and reduced the water loss rate of fruit. Overall, the study of tomato stress response mechanisms and the identification of key genes regulating fruit hardness are beneficial to the improvement of tomato resistance. It is also conducive to the improvement of tomato quality. The research results can lay a foundation for the enhancement of fruit storage tolerance and stress resistance. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) has been proven to be a multifunctional signaling molecule in plants. In this study, we attempted to explore the effects of H2S on the climacteric fruit tomato during postharvest storage. H2S fumigation for 1 d was found to delay the peel color transition from green to red and decreased fruit firmness induced by ethylene. Further investigation showed that H2S fumigation downregulated the activities and gene expressions of cell wall-degrading enzymes pectin lyase (PL), polygalacturonase (PG), and cellulase. Furthermore,H2S fumigation downregulated the expression of ethylene biosynthesis genes SlACS2 and SlACS3. Ethylene treatment for 1 d was found to induce the expression of SlACO1, SlACO3, and SlACO4 genes, whereas the increase was significantly inhibited by H2S combined with ethylene. Furthermore, H2S decreased the transcript accumulation of ethylene receptor genes SlETR5 and SlETR6 and ethylene transcription factors SlCRF2 and SlERF2. The correlation analysis suggested that the fruit firmness was negatively correlated with ethylene biosynthesis and signaling pathway. The current study showed that exogenous H2S could inhibit the synthesis of endogenous ethylene and regulate ethylene signal transduction, thereby delaying fruit softening and the ripening process of tomato fruit during postharvest storage. [ABSTRACT FROM AUTHOR]

Highlights • A loss of blueberry fruit firmness corresponded to extensively fractured cell microstructures. • HCl-soluble pectins were converted to water-soluble pectins during early ripening. • Arabinose levels in HCl-soluble pectins were substantially lost, correlating with fruit softening. • Pectin modifying enzyme activities were high during early ripening, whereas α-mannosidase activity increased during late ripening. • Cell wall-related processes are a key feature of early ripening in blueberries. Abstract Blueberry fruits undergo rapid softening, which has important consequences for postharvest shelf life. However, the mechanism of softening is not well understood. Here, we examined fruit quality characteristics and cell wall-associated fruit softening in 'Bluecrop' highbush blueberry by investigating cell wall composition, cell microstructure, and cell wall modifying enzyme activities at different fruit ripening stages. Fruit firmness significantly declined during ripening, with the greatest reduction between the pale green and reddish purple stages. The decrease in firmness corresponded to an extensively fractured microstructure in the parenchyma tissues and positively correlated with reductions in the contents of fruit cell wall materials. The increased amount of water-soluble pectins correlated with a decline in HCl-soluble pectins during ripening. A substantial loss of arabinose and a decreased ratio of arabinose and galactose to rhamnose in HCl-soluble pectins significantly correlated with fruit softening. Hemicellulose was significantly reduced, mainly between the pale green and reddish purple stages, showing a significant positive correlation with fruit firmness. Polygalacturonase, α-arabinofuranosidase, and β-galactosidase showed higher activities during early ripening, whereas the activities of α-mannosidase and endo-1,4-β-xylanase were higher during late ripening. These results indicate that cell wall-related processes are a key feature of early ripening in 'Bluecrop' highbush blueberry fruits. Our results set the stage for efforts to improve fruit shelf life by managing softening-related fruit losses in highbush blueberries. [ABSTRACT FROM AUTHOR]

Sunburn damage due to excessive solar radiation is one of the major problems affecting the avocado fruit production. Shade netting has been introduced so that growers can cover their orchards with the nets to protect their trees/fruit. However, little is known on the effect of different coloured shade netting on avocado fruit quality. Thus, the influence of blue, red and white photo selective netting on marketable yield, physicochemical characteristics and incidence of anthracnose in ‘Hass’ avocado fruit was investigated. Blue and white netting improved the marketable yield, and accelerated fruit ripening after 28 d cold storage at 5.5 °C followed by 5 d at shelf-life conditions. Ripening, as indicated by fruit softening, correlated well with the content of d -mannoheptulose. The concentration of α–tocopherol, oleic acid and phenolic acids was also affected by growing conditions, due to different coloured shade netting being used. However, incidence of anthracnose was reduced on the 5th d at shelf-life conditions due to delayed ripening, higher phenylalanine ammonia lyase activity, and epicatechin content in the pericarp. White and blue netting appear to be a suitable pre-harvest tool to improve the marketable yield. [ABSTRACT FROM AUTHOR]

Studies on the maturation of mangoes in growing regions may help determine the optimal harvest strategies to support proper post-harvest handling and improve the fruit shelf life. The aim of the present study is to evaluate changes and establish correlations of physical and mechanical parameters during the ripening of mangoes cv. 'Tommy Atkins' collected from fifty plant rows in a commercial orchard. The fruits were picked at 35, 50, 65, 80, 95, 110, 125 and 135 days after flowering (DAF). Fruit mass, longitudinal diameter (LD), transverse diameter (TD), fruit firmness, force and maximum deformation compression, tension and Hencky's strain were evaluated. The statistical design was totally randomized with four replications with ten fruits each. The results were submitted to longitudinal data analysis due to the quantitative nature imposed by the harvest time factor. Hencky's strain curves and deformity underwent an analysis of the standard error of the mean. From the beginning of the harvest up to 125 DAF, the fruit went through an increase in its mass, in its longitudinal and transverse diameters and in its compressive strength. Both physical and mechanical parameters exhibited high correlation, up 0.93, as regards the fruit maturation stages. This demonstrates that the mangoes cv. 'Tommy Atkins' hold excellent prospects of development. [ABSTRACT FROM AUTHOR]

Ripening is a highly coordinated, irreversible event involving a series of physiological and biochemical changes, leading to the development of a soft fruit. One of the limiting factors that influence the economic value of fruit is the relatively short ripening period and limited shelf-life. In climacteric fruit, ethylene is a key regulator of ripening; however, recent research has shown that auxin also plays an important role during the event. To understand the contributions of ethylene, auxin and their interaction in ripening, two plum cultivars with widely varying fruit ripening behaviors were compared. The early cultivar, EG, exhibited a brief ripening process in association with rapid decline in firmness. The late cultivar, V9, displayed slow ripening behavior accompanying by notable extension in fruit firmness, resulting in prolonged shelf-life along with preserved fruit quality traits. Auxin has been suggested to play an indirect role in promoting fruit ripening via stimulating the transcription of several ethylene components, resulting in ethylene-induced fruit ripening and softening. This study shows further that there is a direct involvement of auxin in advancing ripening events independent of ethylene action through stimulating the transcription of several genes that encode cell-wall metabolism-related proteins critical for determining the fruit softening rate and potential shelf-life. These results support the hypothesis that the autonomous role played by auxin is as important as that of ethylene in determining not only fruit ripening behavior, but also in mediating other fruit quality traits including shelf-life. [ABSTRACT FROM AUTHOR]

Fruit ripening and softening are key traits for many fleshy fruit. Since cell walls play a key role in the softening process, expansins have been investigated to control fruit over ripening and deterioration. In tomato, expression of Expansin 1 gene, SlExp1 , during fruit ripening was associated with fruit softening. To engineer tomato plants with long shelf life, we screened for mutant plants impaired in SlExp1 function. Characterization of two induced mutations, Slexp1-6_W211S , and Slexp1-7_Q213Stop , showed that SlExp1 loss of function leads to enhanced fruit firmness and delayed fruit ripening. Analysis of cell wall polysaccharide composition of Slexp1-7_Q213Stop mutant pointed out significant differences for uronic acid, neutral sugar and total sugar contents. Hemicelluloses chemistry analysis by endo-β-1,4- d -glucanase hydrolysis and MALDI-TOF spectrometry revealed that xyloglucan structures were affected in the fruit pericarp of Slexp1-7_Q213Stop mutant. Altogether, these results demonstrated that SlExp1 loss of function mutants yield firmer and late ripening fruits through modification of hemicellulose structure. These SlExp1 mutants represent good tools for breeding long shelf life tomato lines with contrasted fruit texture as well as for the understanding of the cell wall polysaccharide assembly dynamics in fleshy fruits. [ABSTRACT FROM AUTHOR]

Banana is one of the most consumed tropical fruits around the world. It is marketed nearly all year-around and has a relatively short shelf life. Fruits are harvested mature green and treated with ethylene to stimulate ripening before distribution and sale. The fruits generally ripen within 4-5 days after ethylene treatment and sold primarily at yellow stage of ripening. After turning yellow the fruit becomes unsuitable for marketing in 1-3 days. Thus 1-2 days of improvement in the fruit shelf life could enhance the market value of banana. Previous studies conducted in our laboratory have demonstrated that both pre- and postharvest application of lysophosphatidylethanolamine (LPE) can retard aging and improve shelf life of various fruits. The objective of this study was to investigate the possibility of improving shelf life of banana fruit by a postharvest dip in LPE. For this purpose, whole fruits obtained from the market at ripeness stage of 2.5 (about 75% green) were dipped in solution of 500 ppm LPE for 30 minutes and observed for a period of five days at room temperature. Each treatment was applied to 50 uniform fruits. From each hand bought, an equal number of fruits were separated for LPE and control treatments to reduce the variability. Five days after dip treatment, the fruit treated with LPE were firmer and thicker as compared with the control. Starch breakdown was also delayed in the LPE-treated fruits. LPE treatment slowed the development of brown spots on the peel tissue. Both peel and pulp tissue of LPE-treated fruits had lower ion leakage compared with the control. Fruit peel slices treated with LPE for 3 hours also showed a decrease in ion leakage and respiration rate at 24 hours after treatment. Results of the present study indicate that a postharvest dip treatment with LPE may improve shelf life of banana fruit by 1-2 days. These results suggest that LPE may improve shelf life by maintaining membrane integrity, reducing respiration, and slowing the breakdown of starch and cell walls during ripening and senescence of banana fruit tissue. [ABSTRACT FROM AUTHOR]

The effects of bagging on fruit characteristics and its role in physical fruit protection were investigated in three pitaya cultivars: Vietnam White (VN-White) and Chuchi Liu (Hylocereus undatus), and Chaozou 5 (Hylocereus sp.). The experiment comprised four treatments: paper-white bag (P-WB), net screen-black bag, polyethylene plastic- black bag (PP-BB), polyethylene plastic-white bag (PP-WB) and non-bagged control. Fruit bagging did not change the fruit lightness but significantly affected other peel colorimetric parameters. VN-White fruits bagged with P-WB became redder (a* = 27.6), less yellow (b* = 4.4) and had higher colour purity (h8 = 10.7) than non-bagged fruits. Fruits with P-WB in Chuchi Liu also showed significant difference in b* and h8 values as compared with control. Bagging with PP-BB or PP-WB in Chaozou 5 also produced redder fruits (a* = 31.7 and 30.3) with more colour intensity (C* 5 32.4 and 31.3) than non-bagged fruits. There were no significant differences in fruit size and weight, total soluble solids content and fruit ripening duration among treatments in all three cultivars. Fruit firmness also exhibited no significant differences among most treatments except for PP-BB, which gave a lower value than other treatments. In general, fruit bagging could reduce the peel thickness but could not increase the edible fruit rate. The most important role of fruit bagging was to effectively protect fruits from physiological factors such as cracking, bird damage and blemish, which led to the significant decrease of the total damaged and defective fruits (13.7 - 33.3%), as compared with non-bagged control (66.7 - 72.6%). [ABSTRACT FROM AUTHOR]

Vitamin B6 plays a crucial role in plant metabolism. It acts as a cofactor in over 140 reactions and has a potent antioxidant function, as described in plant growth and development related to root and leaf tissues, but not yet in fruit ripening. Here, we aimed to explore simple practices to improve endogenous content of vitamin B6 in avocados, measured by high-performance liquid chromatography (HPLC), and to evaluate to what extent and through which mechanisms pyridoxal-5′-phosphate (PLP) treatment influences fruit quality during postharvest ripening and cold storage. Emphasis was put on evaluating a possible link between vitamin B6 and phytohormones by performing hormonal profiling analyses using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). We hypothesized that PLP could improve quality parameters and prolong the shelf life of fruit. Results showed that Bacon avocados had a low vitamin B6 content compared to Hass and other varieties. However, basic techniques like short-term cold storage increased the vitamin B6 content 2.5 fold. Exogenous application of vitamin B6 slightly delayed avocado ripening at room temperature and caused reduced softening in the mesocarp, which was related to a hormonal response that was most likely mediated by cytokinins. In long-term cold-stored avocados, PLP treatment triggered γ-tocotrienol and plastochromanol-8 accumulation, which improved the tocochromanol composition in the fruit. In conclusion, the vitamin B6 content of Bacon avocados can be improved through simple practices. Exogenous applications of PLP can be used either to delay ripening of avocados at room temperatures or to increase tocochromanol content in cold-stored fruit. • Cold exposure increases vitamin B 6 content in Bacon avocados. • Pyridoxal 5′-phosphate treatment delays early fruit softening mediated by hormones. • Pyridoxal 5′-phosphate treatment triggers γ-tocotrienol and plastochromanol-8 accumulation in cold-stored fruit. [ABSTRACT FROM AUTHOR]

Peach softening is usually attributed to the dismantling of the cell wall in which endo-polygalacturonase (endo-PG)- catalysed depolymerization of pectins plays a central role. In this study, the hypothesis that the function of endo-PG is critical for achieving a melting flesh fruit texture but not for reducing fruit firmness was tested by comparing pericarp morphology and endo-PG expression and localization in melting (MF) and non-melting flesh (NMF) fruit at successive stages of ripening. MF Bolero, Springbelle, and Springcrest, and NMF Oro-A and Jonia cultivars were analysed. Both MF and NMF fruit were left to ripen on the tree and reached a firmness of <10 Newtons (N). The image analysis of pericarp tissues revealed that during softening the loss of cell turgidity was a process common to mesocarp cells of all MF and NMF fruit and was clearly visible in peaches with a firmness of less than ~20 N. In contrast, the loss of cell adhesion was a feature exclusively observed in ripe MF fruit pericarp. In this ripe fruit, large numbers of endo-PG isoforms were highly expressed and the enzyme localization corresponded to the middle lamella. As a consequence, wide apoplastic spaces characterized the pericarp of ripe MF peaches. In contrast, no loss of cell adhesion was observed in any NMF fruit or in unripe MF peaches. Accordingly, no endo-PG was detected in unripe NMF fruit, whereas few and poorly expressed enzyme isoforms were revealed in ripe NMF and in unripe MF peaches. In this fruit, the poorly expressed endo-PG localized mainly in vesicles within the cytoplasm and inner primary cell wall. On the whole the results suggested that endo-PG function was needed to achieve melting flesh texture, which was characterized by wide apoplastic spaces and partially deflated mesocarp cells. Conversely, endo-PG activity had no critical influence on the reduction of fruit firmness given the capacity of NMF peaches to soften, reaching values of 5–10 N. As in tomato, the change of symplast/apoplast water status seems to be the main process through which peach fruit regulates its firmness. [ABSTRACT FROM AUTHOR]

Abstract: Two transgenic strawberry lines (Pel 1 and Pel 3) containing the open reading frame of a fruit specific strawberry pectate lyase gene (FaplC) under the control of the CaMV35S promoter have been obtained to evaluate the role of this gene on fruit softening. Ripen fruits from both lines showed a significant down-regulation of FaplC, being the percentage of silencing of 84 and 71% on Pel 1 and Pel 3, respectively. The agronomic behaviour of transgenic plants was evaluated during two consecutive years. Fruit set increased in the two transgenic lines when compared with control plants, although Pel 1 showed a significant reduction on fruit weight. Firmness of full ripen fruits from Pel lines was significantly higher than control fruits, while color and soluble solids were not affected. The increase of firmness in Pel lines was maintained when ripe fruits were stored for 3 days at 25°C. Histological analysis of ripe fruits showed lower intercellular spaces and a higher degree of cell to cell contact area in transgenic fruits when compared with controls. Altogether, these results suggest a direct relationship between pectate lyase gene expression and strawberry fruit softening. [Copyright &y& Elsevier]

Skin of ‘Hass’ avocados (Persea americana Mill.) changes colour from green to purple/black as fruit ripen. This colour change is important as an indicator of ripeness for both industry and consumers. We sought to characterise pigment changes during ripening of ‘Hass’ avocados. Skin colour and changes in chlorophyll and anthocyanin concentrations in relation to fruit firmness at three ripening temperatures (15, 20 and 25 °C) were studied. As fruit ripened, skin colour changed from green, to purple, to black, which was observed as a decrease in L, chroma and hue. Total anthocyanins in skin tissue increased during ripening, but this increase was due almost entirely to a single anthocyanin; cyanidin 3-O-glucoside. Cyanidin 3-O-glucoside concentration increased after 3–6 days postharvest (depending on ripening temperature), and levels increased earlier, and were higher, with higher ripening temperature. Chlorophyll a and b levels decreased until 4–5 days after harvest, but did not change significantly thereafter. No significant differences in chlorophyll concentration were observed among the three ripening temperatures. Fruit harvested directly from the tree (unripe) with skin darkening showed similar pigments changes to that during ripening (reduced chlorophyll and increased cyanidin 3-O-glucoside). Colour change in ‘Hass’ avocados from green to purple, then black, results from an initial decrease in chlorophyll content, followed by an increase in the levels of the anthocyanin, cyanidin 3-O-glucoside. [Copyright &y& Elsevier]

Silverleaf whitefly (SLW) (Bemisia argentifolii Bellows and Perring) feeding on tomato (Lycopersicon esculentum Mill.) plants induces a disorder in the fruit known as irregular ripening. The effects of silverleaf whitefly feeding on ripening of tomato fruit both attached to and detached from the plant are described. ‘Florida Petite’ tomatoes free of SLW, attached to the plant, began an ethylene climacteric between 40 and 45 days after anthesis (DAA), coincident with a rapid increase in red color and loss of firmness. The ethylene climacteric began between 45 and 50 DAA in tomato fruit from plants infested with SLW, and the fruit developed less red color and softened less than did fruit from plants free of SLW. Fruit harvested 45 DAA from plants free of SLW reached the respiratory and ethylene climacteric peak 3 days after harvest, developed normal red color, and softened similar to fruit ripened on the plant. In contrast, fruit harvested 45, 50 or 55 DAA from SLW-infested plants showed no respiratory or ethylene climacteric, had poor color development, and did not soften to the same extent as did fruit from plants free of SLW. [Copyright &y& Elsevier]

In order to improve environmental sustainability of tomato cultivation and the quality of the harvested fruits, we tested (a) the digestate from anaerobic fermentation of buffalo slurries as partial replacing of NP fertilizers and (b) the biodegradable mulching to improve the nutrients and water availability for crop and to control weeds. In 2017–2018, a private farm of Campania region hosted a trial with four treatments deriving from the combination of two experimental factors: (1) fertilization strategy (standard farm NPK fertilization vs. digestate combined with reduced rates of NP fertilizers); (2) soil mulching (biodegradable mulching vs. no mulching). We measured fresh and dry aboveground biomass (fruits and stem + leaves), yields, fruits quality. Results pointed out: (1) combination of digestate with reduced rates of NP fertilizers did not decrease yields compared to complete mineral fertilization; (2) yields were improved in 2017 by synergic effects of soil mulching and combination of digestate and reduced rates of NP fertilizers; (3) in both the years, digestate combined with reduced rates of NP fertilizers and soil mulching determined the significant improving of fruits quality parameters interesting the processing industry, namely, fruit color, and firmness, total soluble solids, titratable acidity while antioxidant activity, contents of ascorbic acid, polyphenols, flavonoids, and lycopene showed responses variable with year or cultivar. [ABSTRACT FROM AUTHOR]