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Calcium chloride treatment is an effective preservative that is widely utilized for the purpose of maintaining the quality of harvested fruits. A 5% calcium chloride solution was utilized for the soaking of postharvested passion fruit stored under ambient conditions for a period of eight days. The textural properties, pectins, hemicellulose content, and enzyme activities in passion fruit peels were determined through a series of analytical procedures. These enzymes were found to be involved in the carbohydrate metabolism of the fruit peels. Furthermore, the data were subjected to correlation determination and principal component analysis. The findings demonstrated that the calcium ion treatment preserved the firmness, elasticity, glutenability, cohesion, resilience, and chewiness of passion fruit while regulating the alterations in pectin and hemicellulose content observed in the treated fruit peels. The treatment also resulted in a reduction in the activities of cell wall-metabolizing enzymes within the fruit peel, leading to a slowing down of the degradation of cell wall materials. The corresponding activities of polygalacturonase, pectin methylesterase, cellulase, and β-galacturonase in the fruit peels were found to be reduced following the treatment. It can therefore be concluded that the calcium chloride treatment is an effective method of maintaining the quality of passion fruit by regulating the carbohydrate metabolism in the fruit peels and achieving a fruit preservation effect. [ABSTRACT FROM AUTHOR]

The surface of prune fruit has a thick layer of frosting, which is easily damaged and lost during prunes harvest or postharvest handling, and there is no clear information on the effect of prune surface frost on postharvest storage quality. To investigate the effect of fruit frosting on the softening of prune fruits during storage under vibration stress, prunes were divided into three grades according to fruit frosting in this study and were vibrated for 8 h at a frequency of 5 Hz at 4 °C; then, samples were selected once every 8 d. The results showed that the heavy fruit frosting (HFF) group maintained higher hardness (21.47%), L* (20.85%), and total soluble solids (12.79%) levels at the end of storage and inhibited cell wall-modifying enzyme activities (polygalacturonase, pectin methylesterase, glycosidase, β-glucosidase, and cellulase) compared to frosting-less fruit (FF) group. This group also showed improved expression of key cell wall-modification genes (ADPG2, PME31, CESA1, BGAL3, XTH33, BGLU41) as well as chelate-soluble pectin (72.11%), Na2CO3-soluble pectin (42.83%), and cellulose (36.89%) solubilization and maintained lower water-soluble pectin (34.23%). Microscopic observations showed that the fruit frosting could delay the dissolution of pectin components and protect the cell wall structure. In summary, fruit frosting can effectively inhibit fruit softening and maintain fruit quality. [ABSTRACT FROM AUTHOR]

Growth-regulating factor (GRF) is a plant-specific family of transcription factors crucial for meristem development and plant growth. Sorghum (Sorghum bicolor L. Moench) is a cereal species widely used for food, feed and fuel. While sorghum stems are important biomass components, the regulation of stem development and the carbohydrate composition of the stem tissues remain largely unknown. Here, we identified 11 SbGRF-encoding genes and found the SbGRF expansion driven by whole-genome duplication events. By comparative analyses of GRFs between rice and sorghum, we demonstrated the divergence of whole-genome duplication (WGD)-derived OsGRFs and SbGRFs. A comparison of SbGRFs' expression profiles supports that the WGD-duplicated OsGRFs and SbGRFs experienced distinct evolutionary trajectories, possibly leading to diverged functions. RNA-seq analysis of the internode tissues identified several SbGRFs involved in internode elongation, maturation and cell wall metabolism. We constructed co-expression networks with the RNA-seq data of sorghum internodes. Network analysis discovered that SbGRF1, 5 and 7 could be involved in the down-regulation of the biosynthesis of cell wall components, while SbGRF4, 6, 8 and 9 could be associated with the regulation of cell wall loosening, reassembly and/or starch biosynthesis. In summary, our genome-wide analysis of SbGRFs reveals the distinct evolutionary trajectories of WGD-derived SbGRF pairs. Importantly, expression analyses highlight previously unknown functions of several SbGRFs in internode elongation, maturation and the potential involvement in the metabolism of the cell wall and starch during post-anthesis stages. [ABSTRACT FROM AUTHOR]

Textural softening is a major factor that limits the storage potential of fruit. Fresh produce markets incur severe financial losses due to excessive fruit softening. The application of preservation strategies aimed at mitigating fruit softening is crucial for optimising the marketability of fruit. Proposed preservation strategies include ecofriendly treatments, namely, hexanal, edible coatings, heat treatments, ozone and UV-C irradiation. These treatments optimise firmness retention by targeting the factors that affect fruit softening, such as ethylene, respiration rates, enzymes and pathogens. This review discusses the mechanisms by which ecofriendly treatments inhibit fruit softening, providing insights into their effect on ethylene biosynthesis, cell wall metabolism and disease resistance. Although ecofriendly treatments offer a promising and sustainable approach for delaying fruit softening, the optimisation of treatment application protocols is needed to improve their efficacy in retaining fruit firmness. Studies reporting on the molecular mechanisms by which ecofriendly treatments inhibit fruit softening are limited. Future studies should prioritise proteomic and transcriptome analyses to advance our understanding of the underlying molecular mechanisms by which ecofriendly treatments delay the fruit-softening process. [ABSTRACT FROM AUTHOR]

Facility-forcing cultivation could effectively improve the quality of 'Beni Madonna' citrus (Citrus nankao × C. amakusa) and advance the ripening period. However, segment drying (KS) before harvest caused fruit quality deterioration and commodity value loss. In this research, we investigated the physiological and molecular characteristics involved in citrus segment drying under facility-forcing cultivation. The juice yield, sugar, acid, vitamin C, and lignin contents in KS fruits were significantly decreased, and the contents of pectin and cellulose were significantly increased. The relative contents of abscisic acid and abscisic acid glucosyl ester in KS fruits were significantly decreased. A total of 1215 differentially expressed genes (DEGs) were screened by transcriptome sequencing. DEGs were significantly enriched in water metabolism, sugar metabolism, transportation, cell wall and phenylpropanoid biosynthesis, and plant hormone signal transduction. The decrease in water absorption and sugar synthesis, the increase of pectin and cellulose synthesis, and the decrease in ABA accumulation may be the main reasons that cause citrus fruit segments to dry under facility-forcing cultivation. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

'Ruixue' apples were used as the test material to study the effect of 10 μM methyl jasmonate (MeJA) on the quality and cell wall metabolism of apples after 18 d of storage. The results showed that MeJA significantly decreased the respiratory rate, reduced the titratable acid content and maintained a high soluble solids content. MeJA has been shown to suppress the activities and gene expressions of WSP, CSP, ISP, and cellulose in contrast to the control group, thereby maintaining a lower cell permeability and higher exocarp firmness. MeJA significantly decreased the expression of MdACS, MdACO, MdPL, Mdgal, and MdPG genes in the apple exocarp when compared to the control group. In addition, the overexpression of MdPL18 increased the content of cell wall polysaccharides such as WSP and CSP, enhanced cell wall-degrading enzyme activities, and accelerated fruit ripening and softening, whereas silencing MdPL18 did the opposite. Together, these results demonstrate that exogenous MeJA maintains the Ruixue apple fruit quality by regulating the metabolism of cell wall substances. [ABSTRACT FROM AUTHOR]

We investigated the effect and underlying mechanism of postharvest treatment with 0.5 mmol/L melatonin (MT) treatment 1 h on chilling injury (CI) and ripening of ‘Guifei’ mango fruits during 4 days of shelf life at 25 ℃ after refrigeration at 4 ℃ for 28 days. The results showed that MT treatment markedly decreased CI and enhanced soluble solids content (SSC), respiration rate and ethylene production, while accelerating the decline in hue value and firmness of chilled mango fruits. Compared with the control group, MT treatment promoted the increase in the contents of water-soluble pectin (WSP) and chelate-soluble pectin (CSP) and the activities of polygalacturonase, β-galactosidase and endo-1,4-β-D-glucanase and accelerated the decrease in pectin methylesterase activity, thereby leading to cell wall degradation and fruit softening. Compared with the control group, higher activities of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) and the expressions of their encoding genes (MiACS and MiACO) were observed in MT-treated fruits. Moreover, MT up-regulated the expression of MiETR1, MiERS1, MiERF1, MiEIN2, MiCBF1 and MiICE1 while down-regulating the expression of MiCTR1. These results indicated that MT treatment could promote the restoration of ripening and reduce CI in mango fruits during shelf life after storage at low temperature.

Objective: To investigate the effect of dielectric barrier discharge cold plasma (DBD) treatment on the cell wall metabolism and softening characteristics of Xiaobai apricot during storage. Methods: Xinjiang-grown Xiaobai apricot fruits were treated with DBD for 40 s (voltage of 90 kV), and stored at 4 ℃ and 95% relative humidity for up to 42 days. The contents of cell wall components, cell wall metabolic enzyme activities, and quality indicators of apricot fruits were measured every seven days. Results: DBD treatment improved the quality of apricot, reduced the contents of malondialdehyde (MDA) and hydrogen peroxide, and significantly inhibited cell wall-degrading enzymes. It also delayed the dissolution of pectin and the degradation of cellulose, and inhibited the migration and loss of water in apricot fruits. Transmission electron microscopy (TEM) showed that DBD treatment helped to maintain the cell wall structure, thus making it more uniform and complete. Conclusion: DBD treatment can effectively inhibit the activities of cell wall-degrading enzymes of apricot fruits during storage, thereby enhancing the cell wall structure and delaying fruit softening.

The hardness of ‘Rio Red’ grapefruits treated postharvest with carboxymethyl chitosan (CMCS), Cryptococcus laurentii or C. laurentii induced by CMCS was measured during storage. The results showed that compared with the control group (treatment with sterile water), CMCS-C. laurentii treatment significantly maintained the firmness of grapefruits during storage (P < 0.05). Moreover, fruit mass loss percentage and the polysaccharide content and polysaccharide hydrolase activity of the cell wall were measured and cell wall microstructure was observed during storage for 75 days. The results indicated that CMCS-C. laurentii treatment was effective in maintaining the contents of sodium carbonate soluble pectin (SCSP) and 24% KOH-soluble fraction (24KSF) and reducing the contents of water-soluble pectin (WSP), ionic-soluble pectin (ISP) and 4% KOH-soluble fraction (4KSF) in the fruit. Compared with the control group, the activities of the cell wall-degrading enzymes pectin methylesterase (PE), polygalacturonase (PG), cellulase (CX), α-L-arabinofuranosidase (α-L-Af) and β-galactosidase (β-Gal) were significantly inhibited by CMCS-C. laurentii treatment. In the middle and later stages of storage, the cell wall structure of the fruit treated with CMCS-C. laurentii was more stable and the intracellular structure was relatively intact. In conclusion, CMCS-C. laurentii treatment can slow down the degradation of organelles and cell walls in postharvest grapefruits, maintain cell integrity better and delay fruit softening.

The mechanisms of the nitrogen deficiency (ND) response are complex and not sufficiently studied in evergreen tree crops. The aim of this study was to investigate the nitrogen deficiency response in two contrasting tea genotypes to reveal molecular crosstalk between tea quality and tolerance to ND. The transcriptional response to two- and four-month nitrogen deficiency was analyzed in tolerant (cv. Karatum) and susceptible (cv. Kolkhida) tea genotypes. Both GO and KEGG analyses indicated that phenylpropanoid pathway was significantly enriched under nitrogen deficiency in both cultivars. Most of the transcription factor DEGs were related to ABA-mediated stress responses; the following transcription factors were upregulated in both genotypes and in both stress periods: TEAK026346 (bZip23), TEAK015869 (RADIALIS-like 3 isoform X1), TEAK022547 (bHLH78) and one was downregulated TEAK030189 (MYB family transcription factor EFM like) indicating their important role for regulation of nitrogen deficiency response. Gene network of phenylpropanoid pathway DEGs indicated the abandoned edges in lignin biosynthesis DEGs. Generally, the results suggest greater stability of the cell wall metabolism and secondary metabolism in tolerant genotype under long term nitrogen deficiency. The revealed lignin biosynthesis genes can be new candidates for molecular breeding to develop tolerant tea genotypes.

Salt stress is one of the major abiotic stresses that damage the structure and composition of cell walls. Alginate oligosaccharides (AOS) have been advocated to significantly improve plant stress tolerance. The metabolic mechanism by which AOS induces salt tolerance in rice cell walls remains unclear. Here, we report the impact of AOS foliar application on the cell wall composition of rice seedlings using the salt-tolerant rice variety FL478 and the salt-sensitive variety IR29. Data revealed that salt stress decreased biomass, stem basal width, stem breaking strength, and lodging resistance; however, it increased cell wall thickness. In leaves, exogenous AOS up-regulated the expression level of OSCESA8, increased abscisic acid (ABA) and brassinosteroids (BR) content, and increased β-galacturonic activity, polygalacturonase activity, xylanase activity, laccase activity, biomass, and cellulose content. Moreover, AOS down-regulated the expression levels of OSMYB46 and OSIRX10 and decreased cell wall hemicellulose, pectin, and lignin content to maintain cell wall stability under salt stress. In stems, AOS increased phenylalamine ammonia-lyase and tyrosine ammonia-lyase activities, while decreasing cellulase, laccase, and β-glucanase activities. Furthermore, AOS improved the biomass and stem basal width and also enhanced the cellulose, pectin, and lignin content of the stem, As a result, increased resistance to stem breakage strength and alleviated salt stress-induced damage, thus enhancing the lodging resistance. Under salt stress, AOS regulates phytohormones and modifies cellulose, hemicellulose, lignin, and pectin metabolism to maintain cell wall structure and improve stem resistance to lodging. This study aims to alleviate salt stress damage to rice cell walls, enhance resistance to lodging, and improve salt tolerance in rice by exogenous application of AOS. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The interactions between plants, beneficial bacteria and their environment are profoundly shaped by various environmental factors, including light, temperature, water availability, and soil quality. Despite efforts to elucidate the molecular mechanisms involved in the association between plants and beneficial bacteria, like Plant Growth-Promoting Bacteria (PGPB), with many studies focusing on the transcriptional reprogramming in the plant, there is no report on the modulation of genetic controls from both plant and associated bacteria standpoints, in response to environment. The main goal of this study was to investigate the relationship between plant-bacteria-environment signaling, using as a model maize plants inoculated with H. seropedicae ZAE94 and cultivated with different doses of N (0.3 and 3 mM). For this purpose, we performed rRNAdepleted RNA-seq to determine the global gene expression of both maize roots and associated H. seropedicae ZAE94. Our results revealed a differential modulation of maize nitrogen metabolism, phytohormone and cell wall responses when associated with H. seropedicae ZAE94 at different N concentrations. In parallel, a modulation of the bacterial metabolism could be observed, by regulating genes involved in transport, secretion system, cell mobility, oxidoreductases, and chemotaxis, when bacteria were associated with maize roots and cultivated at different doses of N. The molecular and phenotypic data of maize plantlets suggested that different doses of N fertilization differentially regulated the beneficial effects of bacterial inoculation, as higher doses (3 mM) favored shoot elongation and lower doses (0.3 mM) favored increase in plant biomass. Our results provide a valuable integrated overview of differentially expressed genes in both maize and associated H. seropedicae ZAE94 in response to different N availability, revealing new insights into pathways involved in grass-PGPB associations. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract During postharvest storage, the metabolism of cell wall components greatly affects the quality of fruits and vegetables. Utilizing 1‐methylcyclopropene (1‐MCP) as an ethylene receptor inhibitor and modified atmosphere (MA) separately or in combination (1‐MCP+MA) were investigated for their impact on Zizania latifolia quality during postharvest storage. The treatments effectively controlled firmness increase, color degradation, and reductions in soluble protein, reducing sugar, total phenol, and ascorbic acid content, with the combined 1‐MCP+MA showing the most significant effect. These treatments also moderately changed soluble pectin, protopectin, cellulose, and hemicellulose content, preserving the activities of essential enzymes and the expression of enzyme genes. The combined treatment particularly demonstrated superior preservation capabilities, holding promise for reducing postharvest losses and maintain the storage quality of edible produce, offering insights for efficient postharvest storage and freshness maintenance of fruits and vegetables.

The softening phenomenon of postharvest fruit will occur after a series of processes such as storage and transportation, and there are many reasons for the occurrence. For example, the material composition and structure of the cell wall are changed due to the action of the enzyme activity related to cell wall metabolism. It may also be due to the changes of related substances after fruit ripening and the regulation of plant hormones, thus promoting fruit ripening and softening. In this paper, the causes of postharvest fruit softening are reviewed, including the synthesis of plant hormones and their binding to receptors to promote fruit softening, the regulation of related transcription factors on fruit softening, and the pathways of cell wall metabolism and carbohydrate metabolism related to fruit softening, in order to provide reference for exploring the mechanism of postharvest fruit softening.

The surface of prune fruit has a thick layer of frosting, which is easily damaged and lost during prunes harvest or postharvest handling, and there is no clear information on the effect of prune surface frost on postharvest storage quality. To investigate the effect of fruit frosting on the softening of prune fruits during storage under vibration stress, prunes were divided into three grades according to fruit frosting in this study and were vibrated for 8 h at a frequency of 5 Hz at 4 °C; then, samples were selected once every 8 d. The results showed that the heavy fruit frosting (HFF) group maintained higher hardness (21.47%), L* (20.85%), and total soluble solids (12.79%) levels at the end of storage and inhibited cell wall-modifying enzyme activities (polygalacturonase, pectin methylesterase, glycosidase, β-glucosidase, and cellulase) compared to frosting-less fruit (FF) group. This group also showed improved expression of key cell wall-modification genes (ADPG2, PME31, CESA1, BGAL3, XTH33, BGLU41) as well as chelate-soluble pectin (72.11%), Na2CO3-soluble pectin (42.83%), and cellulose (36.89%) solubilization and maintained lower water-soluble pectin (34.23%). Microscopic observations showed that the fruit frosting could delay the dissolution of pectin components and protect the cell wall structure. In summary, fruit frosting can effectively inhibit fruit softening and maintain fruit quality.

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Textural softening is a major factor that limits the storage potential of fruit. Fresh produce markets incur severe financial losses due to excessive fruit softening. The application of preservation strategies aimed at mitigating fruit softening is crucial for optimising the marketability of fruit. Proposed preservation strategies include ecofriendly treatments, namely, hexanal, edible coatings, heat treatments, ozone and UV-C irradiation. These treatments optimise firmness retention by targeting the factors that affect fruit softening, such as ethylene, respiration rates, enzymes and pathogens. This review discusses the mechanisms by which ecofriendly treatments inhibit fruit softening, providing insights into their effect on ethylene biosynthesis, cell wall metabolism and disease resistance. Although ecofriendly treatments offer a promising and sustainable approach for delaying fruit softening, the optimisation of treatment application protocols is needed to improve their efficacy in retaining fruit firmness. Studies reporting on the molecular mechanisms by which ecofriendly treatments inhibit fruit softening are limited. Future studies should prioritise proteomic and transcriptome analyses to advance our understanding of the underlying molecular mechanisms by which ecofriendly treatments delay the fruit-softening process.

Growth-regulating factor (GRF) is a plant-specific family of transcription factors crucial for meristem development and plant growth. Sorghum (Sorghum bicolor L. Moench) is a cereal species widely used for food, feed and fuel. While sorghum stems are important biomass components, the regulation of stem development and the carbohydrate composition of the stem tissues remain largely unknown. Here, we identified 11 SbGRF-encoding genes and found the SbGRF expansion driven by whole-genome duplication events. By comparative analyses of GRFs between rice and sorghum, we demonstrated the divergence of whole-genome duplication (WGD)-derived OsGRFs and SbGRFs. A comparison of SbGRFs’ expression profiles supports that the WGD-duplicated OsGRFs and SbGRFs experienced distinct evolutionary trajectories, possibly leading to diverged functions. RNA-seq analysis of the internode tissues identified several SbGRFs involved in internode elongation, maturation and cell wall metabolism. We constructed co-expression networks with the RNA-seq data of sorghum internodes. Network analysis discovered that SbGRF1, 5 and 7 could be involved in the down-regulation of the biosynthesis of cell wall components, while SbGRF4, 6, 8 and 9 could be associated with the regulation of cell wall loosening, reassembly and/or starch biosynthesis. In summary, our genome-wide analysis of SbGRFs reveals the distinct evolutionary trajectories of WGD-derived SbGRF pairs. Importantly, expression analyses highlight previously unknown functions of several SbGRFs in internode elongation, maturation and the potential involvement in the metabolism of the cell wall and starch during post-anthesis stages.

Facility-forcing cultivation could effectively improve the quality of ‘Beni Madonna’ citrus (Citrus nankao × C. amakusa) and advance the ripening period. However, segment drying (KS) before harvest caused fruit quality deterioration and commodity value loss. In this research, we investigated the physiological and molecular characteristics involved in citrus segment drying under facility-forcing cultivation. The juice yield, sugar, acid, vitamin C, and lignin contents in KS fruits were significantly decreased, and the contents of pectin and cellulose were significantly increased. The relative contents of abscisic acid and abscisic acid glucosyl ester in KS fruits were significantly decreased. A total of 1215 differentially expressed genes (DEGs) were screened by transcriptome sequencing. DEGs were significantly enriched in water metabolism, sugar metabolism, transportation, cell wall and phenylpropanoid biosynthesis, and plant hormone signal transduction. The decrease in water absorption and sugar synthesis, the increase of pectin and cellulose synthesis, and the decrease in ABA accumulation may be the main reasons that cause citrus fruit segments to dry under facility-forcing cultivation.

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.

The present research was undertaken in order to study the effect of exogenous fructose treatment on postharvest softening of apricot fruits. ‘Saimaiti’ apricots were subjected to osmotic treatment in 300 mmol/L fructose solution at 0.05 MPa for 2 min followed by normal pressure for another 5 min before storage at (0 ± 1) ℃. Distilled water was used as control treatment. Fruit hardness, cell membrane permeability, water soluble pectin (WSP), chelate soluble pectin (CSP), Na2CO3 soluble pectin (NSP) and cellulose contents, and polygalacturonase (PG), pectin methyl esterase (PME), β-galactosidase (β-Gal) and cellulase (CEL) activities were determined every seven days during storage, and cell ultrastructure was observed by transmission electron microscopy (TEM). The results showed that exogenous fructose treatment could significantly inhibit the activity of cell wall degrading enzymes and maintain the contents of CSP, NSP, and cellulose, thereby inhibiting the degradation of the cell wall. On day 49 of storage, compared with the control group, the contents of CSP, NSP and cellulose in fructose-treated apricot fruits increased by 31.30%, 10.58%, and 14.30% (P < 0.05). The WSP content and cell membrane permeability of the control group were 1.09 and 1.25 times as high as those in the control group, respectively. Furthermore, this treatment maintained the integrity of organelles and the membrane system, and effectively delayed the decline in fruit hardness.

Winter jujube is extremely susceptible to softening and reddening after harvest, resulting in serious quality deterioration. The influences of abscisic acid (ABA) on the storage quality, cell wall metabolism, phenylpropane metabolism, and differentially expressed genes of winter jujube were investigated. The results showed that low concentration of ABA (0.2 mmol L−1) treatment maintained the firmness and greenness of winter jujube, while inhibiting respiration rate and ethylene production after harvest. Compared with control group, ABA treatment inhibited the activities of pectin methylesterase, polygalacturonase, β-1,3-glucanase, α-l-arabinofurosidase, and phenylalanine ammonia-lyase, but improved the activities of cinnamate-4-hydroxylase, 4-coumaric acid CoA ligase, and chalcone synthase. Transcriptome analysis revealed a total of 13,068 differentially expressed genes among control (0 d and 30 d) and ABA (30 d) groups, which were enriched in the phenylpropanoid metabolism, secondary metabolic biosynthesis, and plant hormone signal transduction pathways. In addition, ABA regulated 33, 29, 35, and 30 genes involved in cell wall metabolism, phenylpropane metabolism, plant hormone signal transduction, and related transcription factors respectively, thereby inhibiting softening and reddening, and delaying ripening and senescence to ultimately maintain the storage quality in winter jujube. These results supply a theoretical basis for investigating postharvest biology and developing storage and preservation techniques of winter jujube.

The objective of the present study was to investigate the effects of 1-methylcyclopropene (1-MCP) combined with tea polyphenols coating (TPC) treatments on overall quality and cell wall metabolism of bracken (Pteridium aquilinum var. latiusculum) stored at 4 ± 1 °C. In comparison with the control group, 1-MCP + TPC treatment maintained overall quality, retarded the degradation of cell wall polysaccharides, and inhibited the activities of cell wall degrading enzymes. Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) analysis revealed that 1-MCP + TPC treatment affected the distribution and migration of water in postharvest bracken. Furthermore, fourier-transform infrared spectroscopy (FTIR) indicated that the characteristic peaks of cell wall polysaccharides were influenced by 1-MCP + TPC treatment during storage. In conclusion, the combined treatment of 1-MCP + TPC may be a promising approach to delay senescence and quality deterioration of postharvest bracken. [ABSTRACT FROM AUTHOR]

Flat peach, a predominant fruit consumed in China, is highly susceptible to softening and perishable. The impact of 1-methylcycloproene (1-MCP) fumigation combined with ε-poly-L-lysine (ε-PL) on softening and postharvest reactive oxygen species (ROS) and phenylpropanoid pathway metabolisms in peaches and its relationship to disease resistance were investigated. Findings revealed that a combination of 1 µL L−1 1-MCP and 300 mg L−1 ε-PL effectively suppressed the activity of cell-wall-degrading enzymes and the disassembly of cell wall structure, thus maintaining higher firmness and lower decay incidence. Compared to the control group, the synergistic approach bolstered enzymatic responses linked to disease resistance and ROS-scavenge system, consistently preserving total phenolics, flavonoids, ascorbic acid, and glutathione levels. Concurrently, the accumulation of hydrogen peroxide and malondialdehyde was significantly diminished post-treatment. These results show that there is good synergistic effect between 1-MCP and ε-PL, which could effectively maintain the quality of flat peach fruit by modulating cell wall metabolism and enhancing the resistance. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effect of exogenous melatonin (MT) on cell wall metabolism leading to Chinese plum (Prunus salicina Lindl.) fruit softening. Exogenous MT treatment increased the endogenous MT content in plum fruits before fruit ripening. However, in mature plum fruits, exogenous MT treatment decreased the fruit hardness, pulp hardness, fruit elasticity, contents of ion-bound pectin, covalently-bound pectin, hemicellulose, and cellulose, and activities of xyloglucan endotransglycosylase/hydrolase and endo-β-1,4-glucanase, and increased the water-soluble pectin content, and activities of pectin methyl esterase, pectin lyase, polygalacturonase, β-galactopyranosidase, and α-L-arabinofuranosidase. Transcriptome analysis revealed that the differentially expressed genes (DEGs) associated with cell wall metabolism in the exogenous MT-treated plum fruits were mainly enriched in the pentose and glucuronate interconversions, phenylpropanoid biosynthesis, cyanoamino acid metabolism, and galactose metabolism pathways. Analysis of these DEGs revealed that exogenous MT treatment affected the expression of genes regulating the cell wall metabolism. Overall, exogenous MT treatment promotes the fruit softening of Chinese plum. [ABSTRACT FROM AUTHOR]

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‘Ruixue’ apples were used as the test material to study the effect of 10 μM methyl jasmonate (MeJA) on the quality and cell wall metabolism of apples after 18 d of storage. The results showed that MeJA significantly decreased the respiratory rate, reduced the titratable acid content and maintained a high soluble solids content. MeJA has been shown to suppress the activities and gene expressions of WSP, CSP, ISP, and cellulose in contrast to the control group, thereby maintaining a lower cell permeability and higher exocarp firmness. MeJA significantly decreased the expression of MdACS, MdACO, MdPL, Mdgal, and MdPG genes in the apple exocarp when compared to the control group. In addition, the overexpression of MdPL18 increased the content of cell wall polysaccharides such as WSP and CSP, enhanced cell wall-degrading enzyme activities, and accelerated fruit ripening and softening, whereas silencing MdPL18 did the opposite. Together, these results demonstrate that exogenous MeJA maintains the Ruixue apple fruit quality by regulating the metabolism of cell wall substances.

Salt stress is one of the major abiotic stresses that damage the structure and composition of cell walls. Alginate oligosaccharides (AOS) have been advocated to significantly improve plant stress tolerance. The metabolic mechanism by which AOS induces salt tolerance in rice cell walls remains unclear. Here, we report the impact of AOS foliar application on the cell wall composition of rice seedlings using the salt-tolerant rice variety FL478 and the salt-sensitive variety IR29. Data revealed that salt stress decreased biomass, stem basal width, stem breaking strength, and lodging resistance; however, it increased cell wall thickness. In leaves, exogenous AOS up-regulated the expression level of OSCESA8, increased abscisic acid (ABA) and brassinosteroids (BR) content, and increased β-galacturonic activity, polygalacturonase activity, xylanase activity, laccase activity, biomass, and cellulose content. Moreover, AOS down-regulated the expression levels of OSMYB46 and OSIRX10 and decreased cell wall hemicellulose, pectin, and lignin content to maintain cell wall stability under salt stress. In stems, AOS increased phenylalamine ammonia-lyase and tyrosine ammonia-lyase activities, while decreasing cellulase, laccase, and β-glucanase activities. Furthermore, AOS improved the biomass and stem basal width and also enhanced the cellulose, pectin, and lignin content of the stem, As a result, increased resistance to stem breakage strength and alleviated salt stress-induced damage, thus enhancing the lodging resistance. Under salt stress, AOS regulates phytohormones and modifies cellulose, hemicellulose, lignin, and pectin metabolism to maintain cell wall structure and improve stem resistance to lodging. This study aims to alleviate salt stress damage to rice cell walls, enhance resistance to lodging, and improve salt tolerance in rice by exogenous application of AOS.

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SUMMARY: Pollen development is critical to plant reproduction, but the underlying regulatory molecular mechanisms have not been fully elucidated. The Arabidopsis (Arabidopsis thaliana) EFR3 OF PLANT 3 (EFOP3) and EFR3 OF PLANT 4 (EFOP4) genes encode members of the Armadillo (ARM) repeat superfamily that play key roles in pollen development. Herein, we demonstrate that EFOP3 and EFOP4 are co‐expressed in pollen at anther stages 10–12, but loss‐of‐function of both EFOP3 and EFOP4 leads to male gametophyte sterility, irregular intine, and shriveled pollen grains at anther stage 12. We further established that full‐length EFOP3 and EFOP4 specifically localize to the plasma membrane, and the integrity of these proteins is essential for pollen development. We observed uneven intine, less organized cellulose and reduced pectin content in mutant pollen compared with the wild‐type. These, together with the misexpression of several genes related to cell wall metabolism in efop3−/− efop4+/− mutants, suggest that EFOP3 and EFOP4 may indirectly regulate the expression of these genes to affect intine formation, thus controlling Arabidopsis pollen fertility in a functionally redundant manner. Moreover, transcriptome analysis showed that the absence of EFOP3 and EFOP4 function affects multiple pollen development pathways. These results enhance our understanding of EFOPs proteins and their role in pollen development. Significance Statement: We show that the integrity of EFOP3 and EFOP4 proteins is essential for their specific association with the plasma membrane of pollen, and is required for pollen intine development in Arabidopsis (Arabidopsis thaliana). EFOP3 and EFOP4 may indirectly regulate the expression of cell wall metabolism‐related genes to affect intine formation, thus controlling Arabidopsis pollen fertility in a functionally redundant manner. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Grapevine red blotch virus (GRBV) is the causal agent of grapevine red blotch disease and is known to delay grape ripening. However, grape cell‐wall modifications during GRBV infection are largely unknown, even though the cell wall plays a large role in pathogenicity, viral interactions with host plants, and phenolic extractability during winemaking. Understanding the impact of GRBV infection on cell‐wall metabolism is important for the development of potential mitigations strategies. In this study, high‐throughput transcriptome sequencing was conducted on Vitis vinifera L. 'Merlot' grapes during ripening. The cell‐wall composition, phenolic content, and phenolic extractability at two different commercial harvest points were also determined. RESULTS: Log fold changes indicated a strong induction in diseased grapes at harvest of several transcripts involved in cell‐wall solubilization and degradation. However, these observations did not translate to changes in cell‐wall composition at either harvest point in diseased grapes, potentially suggesting post‐transcriptional regulation. Moderate induction of pectin methylesterase inhibitor transcripts and transcripts associated with pathogenesis‐related proteins coincided with increases in pectin and soluble proteins in cell walls of diseased grapes at harvest. Both pectin and pathogenesis‐related proteins are known to retain phenolic compounds during winemaking. CONCLUSION: Our study corroborates this finding when the percentage extractability of flavonols in wines was significantly lower when made from GRBV‐infected fruit. These results suggest GRBV alters the grape cell walls, consequently decreasing phenolic extraction during winemaking. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The effectiveness of nitric oxide (NO) for control of grey spot rot cause by Pestalotiopsis eriobotryfolia in harvested loquat fruit and its probable mechanisms have been investigated. The results showed that NO donor sodium nitroprusside (SNP) did not evidently inhibit mycelial growth and spore germination of P. eriobotryfolia, but resulted in a low disease incidence and small lesion diameter. SNP resulted in a higher hydrogen peroxide (H2O2) level in the early stage after inoculation and a lower H2O2 level in the latter period by regulating the activities of superoxide dismutase, ascorbate peroxidase and catalase. At the same time, SNP enhanced the activities of chitinase, β-1,3-glucanase, phenylalanine ammonialyase, polyphenoloxidase, and total phenolic content in loquat fruit. However, SNP treatment inhibited the activities of cell wall-modifying enzymes and the modification of cell wall components. Our results suggested that NO treatment might have potential in reducing grey spot rot of postharvest loquat fruit. [ABSTRACT FROM AUTHOR]

The banana is prone to chilling injury (CI) at low temperature and showing a series of chilling symptoms, such as peel browning, etc. Lignification is a response to abiotic stress and senescence, which is an important manifestation of fruits and vegetables during chilling exposure. However, little is known about the lignification of bananas during low-temperature storage. Our study explored the characteristics and lignification mechanism of banana fruits during low-temperature storage by analyzing the changes of chilling symptoms, oxidative stress, cell wall metabolism, microstructures, and gene expression related to lignification. The results showed that CI inhibited post-ripening by effecting the degradation of the cell wall and starch and accelerated senescence by increasing O2− and H2O2 content. For lignification, Phenylalanine ammonia-lyase (PAL) might start the phenylpropanoid pathway of lignin synthesis. Cinnamoyl-CoA reductase 4 (CCR4), cinnamyl alcohol dehydrogenase 2 (CAD2), and 4-coumarate--CoA ligase like 7 (4CL7) were up-regulated to promote the lignin monomer's synthesis. Peroxidase 1 (POD1) and Laccase 3 (LAC3) were up-regulated to promote the oxidative polymerization of lignin monomers. These results suggest that changes of the cell wall structure and cell wall metabolism, as well as lignification, are involved in the senescence and quality deterioration of the banana after chilling injury. [ABSTRACT FROM AUTHOR]

Tarocco blood orange is mainly famous for easy mastication. Mastication is the most important quality attribute contributed or determined by parenchyma cell walls, which consisted of a mixture of pectin, lignin, and cellulose. However, there were few studies associated with the components of cell wall for blood orange during cold storage at present. In the present study, the protopectin content first increased and then decreased, the contents of soluble pectin, lignin and cellulose showed an increasing trend, and the activities of PME, POD and cellulase were consistent with the corresponding changes described above in the three pulp parts during cold storage. Therefore, the easy mastication of blood orange may be attributed to the decreased content of protopectin and increased content of water-soluble pectin during cold storage. Regarding the expression of genes related to pectin, lignin and cellulose metabolism, the upregulated genes PE11, PE17, PE18 and PL5 for pectin metabolism, POD1, POD40, POD55 and LAC15 for lignin accumulation and the downregulated genes EG17 and RLSK8 for cellulose, showed the greatest contributions to the changes of above-mentioned cell wall components during cold storage. [ABSTRACT FROM AUTHOR]

Fruit peel creasing is a serious pre-harvest physiological disorder in citrus, influencing fruit quality, storage, and yield. Four- and eight-year-old 'Hongjiang' oranges grafted onto Canton lemon rootstocks were treated with calcium and calcium inhibitors, respectively, to study the effects of different treatments on fruit creasing rate, mechanical properties of the peel, cell wall metabolism enzyme activities, and the expression of related genes. Foliar application of 0.5% calcium nitrate significantly reduced the fruit creasing rate, while treatment with EGTA and LaCl3, inhibitors of calcium uptake, increased the fruit creasing rate; But the effect of calcium nitrate treatment on changing the mechanical properties of pericarp and inhibiting the activity of hydrolase (PG, Cx and PE) was not very significant. Furthermore, it was observed that the expression levels of genes (PG, Cx, and PE) encoding cell wall-degrading enzymes were significantly lower in the normal fruit peel than in the creased fruit peel. Meanwhile, the expression levels of PG, Cx, and PE were higher in the peel of shaded fruit than in the peel of exposed fruit. During the high incidence period of fruit creasing, calcium nitrate treatment down-regulated the expression of PG, Cx, and PE, while EGTA treatment up-regulated the expression of these genes. In conclusion, foliar spraying of calcium nitrate at the fruit rapid enlargement stage can increase the Ca content in the peel of 'Hongjiang' orange and significantly suppress the expression of cell wall degrading enzymes genes (PG, PE and Cx) in 'Hongjiang' orange peel during the high occurrence period of fruit creasing, resulting in reducing the occurrence of fruit creasing and cracking. [ABSTRACT FROM AUTHOR]

To explore the effect of NO fumigation on cell wall metabolism in Lycium barbarum fresh fruit under cold storage, “Ningqi No. 7” fresh Lycium barbarum fruit was used as the test material, and fumigated with 300 μL/L (0 μL/L NO as control) NO gas for 3 h, and stored at 3±0.5 ℃ for 36 d. The rotting rate, hardness and enzyme activities related to cell wall metabolism were determined regularly.The results showed that 300 μL/L NO treatment inhibited the increase of polygalacturonase (PG), β-galactosidase (β-Gal), cellulase (Cx) and β-glucosidase (β-glu) activities; maintained high content of protopectin in the fresh fruit; reduced the rising rate of soluble pectin content; and alleviated the decline of fruit hardness and the increase of decay rate. It showed that NO treatment mitigated the rate of softening and inhibited the rot decay by decreasing the cell wall metabolism of postharvest Lycium barbarum fresh fruit.

To extend the limited commercial storage of muskmelons due to insufficient shelf life, a heat treatment device with precise temperature control was designed and applied to three muskmelon varieties: "Xizhou Mi 25" (XZM), "Jinmi 3" (JM), and "Jiashi" (JS). The effectiveness of this device and the effect of heat treatment on the softening of muskmelons during storage were evaluated. The results indicated no significant difference between the temperatures set by the control system and the actual measured temperatures (p > 0.05), demonstrating the high accuracy of the temperature control system. After optimization of the heat treatment device, no thermal damage was observed in the heat-treated group of muskmelons. The energy consumption of the heat treatment device was only half that of the insulated tank. By the 18th day of storage, the protopectin (PP) content in the heat-treated group was significantly lower than in the control group. Correlation analysis showed that hardness was positively correlated with PP content and negatively correlated with water-soluble pectin (WSP). Additionally, cell wall metabolism-related enzyme activities were negatively correlated with PP content. These results indicated that the heat treatment effectively delayed muskmelon softening during postharvest storage. This study provides technical support for the industrial application of heat treatment devices in muskmelon preservation. • A heat treatment device with precise temperature control was designed. • The optimized equipment effectively reduced the thermal damage of muskmelons. • The heat treatment device's energy consumption was half that of the insulated tank. • Heat treatment delayed the softening of postharvest muskmelon. [ABSTRACT FROM AUTHOR]

• Citral enhances quality of fresh Gastrodia elata. • Citral inhibited the activity and maintained high enzymatic activities degradation of cell wall-degrading enzymes. • Citral activated the phenylpropane metabolic pathway. • Citral treatment showed great potential to delay soften and senescence in post-harvest Gastrodia elata. Gastrodia elata is a valuable medicinal plant. However, it has a short shelf life, which is the main factor that limits its storage and transportation. The objective of this study was to examine the impact of citral on the interactions between quality, cell wall metabolism, and the phenylpropanoid pathway of G.elata during storage at a low temperature(4 ± 1 °C). The results showed that citral treatment maintained the hardness, titratable acid, soluble solids, soluble proteins, and vitamin C of G.elata and inhibited the increase in the decay index, weight loss, malondialdehyde, and relative conductivity. Citral treatment retained higher levels of protopectin, cellulose, and starch which was achieved by inhibiting the activities of cell wall degradation-related enzymes, including cellulase, amylase, α-amylase, pectinase, β -glucosidase, β -galactosidase, and α-l-arabinofuranosidase, and reduced soluble pectin content, thereby maintaining the cell wall structure of G.elata. In addition, citral application enhanced the enzymatic activities of phenylalanine-ammonia-lyase, 4-coumarate-CoA ligase, cinnamic acid 4-hydroxylase, and cinnamaldehyde dehydrogenase and improved lignin, total phenolic and flavonoid content in G.elata. Collectively, these findings suggest that citral can retard senescence softening and maintain the quality of G.elata by modulating the cell wall metabolism and phenylpropanoid pathway at low temperatures. [ABSTRACT FROM AUTHOR]

Prolonging the fruit storage period is strategically important due to the limitation of postharvest life determined by excessive softening. Efforts have been made to alleviate the issue of fruit softening in transgenic fruit by suppressing genes that encode cell wall-degrading proteins. However, individual genes related to the degradation of cell walls have limited ability, resulting in minimal success. SET domain-containing protein (SET protein) is widely expressed in most plant organs and crucial in plant growth and development. A tomato SET protein was previously identified as SlDDI4 (Solanum lycopersicum DDB1 interacting protein 4) with a H3K9 methyltransferase activity involving cell proliferation and organ size regulation. In this study, we demonstrated that SlDDI4 overexpression (SlDDI4-OE) promotes fruit firmness in addition to increased fruit size. Further experimental investigations revealed that the increased expression of SlDDI4 inhibited cellulase and pectinase activities, consequently increasing the proportion of cellulose and insoluble pectin. RNA-seq profiling indicated the genes involved in cell wall metabolism in SlDDI4-OE fruit were significantly down-regulated. DNA methylation and McrBC-PCR analysis at the SlCEL2 , SlPG2 , and SlEXP12 loci revealed that their down-regulation was associated with the elevated methylation level in the individual promoter regions. Furthermore, up-regulation of SlDDI4 generated fruit with increased lycopene content and prolonging shelf-life by approximately 20 d without adverse impacts on the flavor indicators. Thus, our results suggest that manipulation of SlDDI4 expression enables broad favorable effects on postharvest life as well as fruit size and quality through chromatin remodeling. • Overexpression of SlDDI4 promotes fruit firmness. • SlDDI4 extends tomato shelf-life and boosts nutritional value. • SlDDI4 increases the proportion of cellulose and insoluble pectin in fruit tissue. • SlDDI4 represses cell wall degradation genes via promoter DNA methylation. [ABSTRACT FROM AUTHOR]

The economic impact of fruit cracking in pomegranate products is substantial. In this study, we present the inaugural comprehensive analysis of transcriptome and metabolome in the outermost pericarp of pomegranate fruit in bagging conditions. Our investigation revealed a notable upregulation of differentially expressed genes (DEGs) associated with the calcium signaling pathway (76.92%) and xyloglucan endotransglucosylase/hydrolase (XTH) genes (87.50%) in the fruit peel of non-cracking fruit under bagging. Metabolomic analysis revealed that multiple phenolics, flavonoids, and tannins were identified in pomegranate. Among these, calmodulin-like 23 (PgCML23) exhibited a significant correlation with triterpenoids and demonstrated a marked upregulation under bagging treatment. The transgenic tomatoes overexpressing PgCML23 exhibited significantly higher cellulose content and xyloglucan endotransglucosylase (XET) enzyme activity in the pericarp at the red ripening stage compared to the wild type. Conversely, water-soluble pectin content, polygalacturonase (PG), and β-galactosidase (β-GAL) enzyme activities were significantly lower in the transgenic tomatoes. Importantly, the heterologous expression of PgCML23 led to a substantial reduction in the fruit cracking rate in tomatoes. Our findings highlight the reduction of fruit cracking in bagging conditions through the manipulation of PgCML23 expression. • Calcium content was significantly higher in fruit non-cracking under bagging treatment. • Analysis of outermost pericarp of pomegranate by transcriptome and metabolome. • A notable upregulation of DEGs associated with the calcium signaling pathway in the non-cracking pericarp under bagging. • Heterologous expression of PgCML23 in tomato significantly reduced fruit cracking by strengthening cell wall. [ABSTRACT FROM AUTHOR]

Flat peach, a predominant fruit consumed in China, is highly susceptible to softening and perishable. The impact of 1-methylcycloproene (1-MCP) fumigation combined with ε-poly-L-lysine (ε-PL) on softening and postharvest reactive oxygen species (ROS) and phenylpropanoid pathway metabolisms in peaches and its relationship to disease resistance were investigated. Findings revealed that a combination of 1 µL L−1 1-MCP and 300 mg L−1 ε-PL effectively suppressed the activity of cell-wall-degrading enzymes and the disassembly of cell wall structure, thus maintaining higher firmness and lower decay incidence. Compared to the control group, the synergistic approach bolstered enzymatic responses linked to disease resistance and ROS-scavenge system, consistently preserving total phenolics, flavonoids, ascorbic acid, and glutathione levels. Concurrently, the accumulation of hydrogen peroxide and malondialdehyde was significantly diminished post-treatment. These results show that there is good synergistic effect between 1-MCP and ε-PL, which could effectively maintain the quality of flat peach fruit by modulating cell wall metabolism and enhancing the resistance.

‘Hayward’ kiwifruits were used as the test materials to be irradiated with high energy electron beams at doses of 0 (control), 300, 400 and 500 Gy. The fruits were stored at 0~1 ℃, RH 90%~95% for 90 d. The effects of electron beam irradiation on fruit firmness, cell wall components, softening-related enzyme activities and gene expressions were analyzed. The results showed that the high energy electron beam irradiation kept the firmness, effectively inhibited the degradation of cell wall skeletal material (protopectin and cellulose) and delayed the postharvest ripening and softening of kiwifruits. In further, high energy electron beam irradiation significantly inhibited the activities of polygalacturonase (PG), pectin methylesterase (PME), β-D-galaetosidase (β-Gal) and cellulase (Cx), and reduced the expressions of genes encoding PG, PME, β-Gal and Cx. Among the three treatments, 400 Gy high-energy electron beam irradiation showed the best effect on inhibiting cell wall degrading enzyme activity and gene expression, retaining the integrity of cell structure, and maintaining fruit firmness during storage. The study provided a theoretical basis for the use of high-energy electron beams in postharvest kiwifruit preservation.