Soluble Pectin Content Research Articles

Extracellular polygalacturonase, β-1,4-glucanase and β-xylosidase in Geotrichum citri-aurrantii positively progressed the sour rot incidence in satsuma mandarin fruit

Gaining an understanding of the characteristics that contribute to the infectiousness of pathogens is essential for devising new strategies to control fungal infection. This study aims to identify and clarify the role of cell wall degrading enzymes (CWDEs) secreted by the Geotrichum citri-aurantii pathogen in the development of sour rot disease in Satsuma mandarin fruit. Results from in vivo experiments showed that CWDEs were secreted during arthrospore germination. Genomic sequencing and liquid chromatography-tandem mass spectrometry results unveiled the presence of polygalacturonase (PG), β-1,4-glucanase, α-glucosidase, xyloglucan:xyloglucosyl transferase, and β-xylosidase. Enzyme activity and gene expression analyses exposed the indispensable roles of PG and β-1,4-glucanase in the initial phase, and β-xylosidase during the acute phase of infection. After infection, we observed that the quantities of cellulose, pectin, and hemicellulose declined continuously, while the soluble pectin content rose steadily. Molecular docking analysis demonstrated that the diversity of CWDE binding to substrates complicated the G. citri-aurantii infection process. Furthermore, we determined the importance of asparagine and aspartic acid in PG-substrate interaction and glycine in β-xylosidase-ligand interaction. Taken together, our findings suggest that PG is a crucial target for blocking the development of sour rot in citrus fruit.

Characterization and Pathogenicity of Colletotrichum truncatum Causing Hylocereus undatus Anthracnose through the Changes of Cell Wall-Degrading Enzymes and Components in Fruits.

Anthracnose is one of the destructive diseases of pitaya that seriously affects the plant growth and fruit quality and causes significant yield and economic losses worldwide. However, information regarding the species of pathogens that cause anthracnose in pitaya (Hylocereus undatus) fruits in Gansu Province, China, and its pathogenic mechanism is unknown. Thus, the purposes of our present study were to identify the species of pathogens causing H. undatus fruits anthracnose based on the morphological and molecular characteristics and determine its pathogenic mechanism by physiological and biochemical methods. In our present study, forty-six isolates were isolated from the collected samples of diseased H. undatus fruits and classified as three types (named as H-1, H-2, and H-3), according to the colony and conidium morphological characteristics. The isolation frequencies of H-1, H-2, and H-3 types were 63.04%, 21.74%, and 15.22%, respectively. The representative single-spore isolate of HLGTJ-1 in H-1 type has significant pathogenicity, and finally we identified Colletotrichum truncatum as the pathogen based on the morphological characteristics as well as multi-locus sequence analysis. Moreover, the H. undatus fruits inoculated with C. truncatum had a significantly increased activity of cell wall-degrading enzymes (CWDEs) cellulase (Cx), β-glucosidase (β-Glu), polygalacturonase (PG), and pectin methylgalacturonase (PMG), while having a decreased level of cell wall components of original pectin and cellulose in comparison to control. The average increased activities of Cx, β-Glu, PG, and PMG were 30.73%, 40.40%, 51.55%, and 32.23% from day 0 to 6 after inoculation, respectively. In contrast, the average decreased contents of original pectin and cellulose were 1.82% and 16.47%, respectively, whereas the average increased soluble pectin content was 38.31% in comparison to control. Our results indicate that C. truncatum infection increased the activities of CWDEs in H. undatus fruits to disassemble their cell wall components, finally leading to the fruits' decay and deterioration. Thus, our findings will provide significant evidence in the controlling of pitaya anthracnose in the future.

Cold plasma treatment delays the texture softening of apricot fruit through PAPL-PL-pectin changes

Apricot, a forest fruit with distinct characteristics, has witnessed a continuous expansion of its market scale over the years. However, the high loss rate caused by fruit texture softening poses a significant challenge to the development of the apricot industry. The effect of cold plasma treatment on the texture was investigated. The findings revealed that compared to the control group, the firmness of apricot fruit increased by 49%, 31%, and 30% after treatment for 20, 40, and 60 s, respectively. Applying an optimal cold plasma treatment (20–40 s) can effectively inhibit the degradation of pectin component branches, thereby delaying the increase in water-soluble pectin (WSP) and iron - soluble pectin (ISP) content, reducing the decline in covalent - soluble pectin (CSP) content, ultimately enhancing fruit firmness and extending the storage period of apricot. RNA-seq results revealed the involvement of pectin decomposition mediated by pectin lyase (PL) in the process of texture softening of apricot fruit, with a key role played by the pectin lyase gene (PaPL). These findings not only enrich the mechanism of texture softening of apricot fruit, but also provide valuable insights for utilizing cold plasma in post-harvest preservation of apricot fruit.

Space electric field impacts on softening and cell wall modification of strawberry during cold storage

As an emerging non-contact cold chain preservation technology, the impact of the DENBA+ on plant cell wall metabolism and its mechanism of inhibiting softening have not been addressed. In this study, strawberries were used as an experimental model to investigate the effect of space electric field storage on cell wall metabolism. Compared with the control, 500 V DENBA+ treatment was able to reduce the firmness loss of strawberries by 18.3 % on 18 d. Additionally, the DENBA+ exhibited a pronounced ability to suppress fruit softening enzyme (FaPG1 and FaβGal4) expression, delay the rise in polygalacturonates (PG), pectin methyl esterase (PME), cellulase (Cx), and β-galactosidase (β-Gal) activities, postpone the decline in cell wall matrix (CWM), insoluble solid pectin (ISP), and colloidal soluble pectin (CSP) content along with hemicellulose and cellulose levels while attenuating water-soluble pectin (WSP) accumulation during cold storage period. These findings contribute to the maintenance of fruit cell wall structural integrity with the aim of sustaining strawberry firmness and retarding the progression of aging.

Transcriptomic analysis reveals ozone treatment delays kiwifruit postharvest softening by modulating cell wall metabolism.

Kiwifruit ripening and senescence after harvesting are closely related to its economic value. Transcriptome analysis and biochemical parameters were used to investigate the differences in gene expression levels and the potential regulation of cell wall metabolism in kiwifruit treated with ozone, thereby regulating fruit softening and prolonging postharvest life. Compared to the control group, the activities of the cell wall modification enzyme were lower under ozone treatment, the content of polysaccharide in the cell wall of primary pectin and cellulose was higher, and the content of soluble pectin was lower. Meanwhile, ozone treatment delayed the degradation of the cell wall mesosphere during storage. A total of 20 pectinesterase (PE)-related genes were identified by sequencing analysis. The data analysis and quantitative polymerase chain reaction results confirmed that cell wall modifying enzyme genes played an important role in softening and senescence after harvesting, which may reduce or induce the expression of certain genes affecting cell wall metabolism. Ozone treatment not only regulates active genes such as xyloglucan endo glycosyltransferase/hydrolase, cellulose synthase, polygalacturonase, and PE to maintain the quality of fruit after harvest but also acts synergically with cell wall modifying enzymes to inhibit the degradation of cell wall, resulting in changes in the ultrastructure of cell wall, thereby reducing the hardness of kiwifruit. In addition, according to the results of cis-acting elements, cell wall degradation is also related to downstream hormone signaling, especially PE-related genes. These results provide a theoretical basis for studying the mechanism of firmness and cell wall metabolism difference of kiwifruit and also lay a good foundation for further research.

A Comparison of Watermelon Flesh Texture across Different Ploidy Levels Using Histology and Cell Wall Measurements

Watermelon fruits of different ploidy levels exhibit significant variations in texture. This study aimed to investigate the primary factors that influence texture differences. To achieve this, we conducted an investigation into the differences in fruit texture development using homozygous autogamous diploid (2×) lines and their autotriploid (3×) and autotetraploid (4×) lines ‘Yixuan’. The study investigated fruit development, flesh texture profile analysis (TPA), flesh cell wall polysaccharide content, and flesh cell microstructure analysis in 2×, 3×, and 4× watermelon fruits. The study found that as watermelon fruits matured, several characteristics increased, including fruit weight, TSS (total soluble solids) content, rind hardness, flesh cell size, and cell wall polysaccharide contents such as crude fiber, cellulose, hemicellulose, lignin, and protopectin. In contrast, the flesh texture parameters and soluble pectin content of the flesh cell wall decreased over time. Significant differences in fruit flesh texture and flesh cell structure were observed among fruits of different ploidy levels at the 32 DAP. Specifically, the 2× fruits displayed considerably lower rind hardness, reduced flesh texture (Hardness, Fracturability, Chewiness, Gumminess), and cell density compared to the 3× and 4× fruits. Additionally, the 2× fruits had larger cell sizes than the 3× and 4× fruits. However, there were no significant differences observed in the flesh cell wall polysaccharide contents across various ploidy levels. These findings suggest that the variation in texture among watermelon fruits of different ploidy levels can be attributed to the size and arrangement of the flesh cells. This research provides a foundation for the further exploration of the intrinsic regulatory factors and molecular mechanisms contributing to texture variation in polyploid watermelon fruits.

γ irradiation mediated the inhibitory effect of Ca2+ signals on softening of blueberry fruit during cold storage

Postharvest blueberries tend to soften and rot, resulting in serious fruit waste. Gamma (γ) irradiation can delay the softening of blueberries and improve fruit quality. Calcium is a structural component of plant cell wall and membrane, and plays a role as a second messenger in the physiological process of fruit. To explore the mechanism of inhibiting the softening of cold storage blueberry fruit by γ irradiation, ‘Bluecrop’ blueberry fruit were treated by γ irradiation at a dose of 2.5 kGy, and then combined with calcium ion (Ca2+) inhibitors and intracellular calmodulin antagonists. The Ca2+ fluorescence signals, fruit firmness, protopectin and different soluble pectin contents, cellulose and hemicellulose contents, and hydrolase activities were detected. Results showed that irradiation induced Ca2+ release from intracellular calcium store to generate fluorescence signals. Irradiation mediated the Ca2+ signals to exert a positive effect on fruit firmness of blueberries during cold storage, for the degradation of protopectin and chelator-soluble pectin to water-soluble pectin was reduced by inhibiting activities of polygalacturonase and pectin methylesterase. Therefore, γ irradiation-induced Ca2+ signals played an important role in regulation of pectin-involved fruit softening in blueberries during cold storage. This study provides a theoretical basis for the mechanism of Ca2+ signaling in blueberry storage.

Pectin substances in <i>Cucurbita maxima</i> fruits in the conditions of the North-West of Russia

Currently, pectins are widely used in the food, pharmaceutical industry, medicine and other industries due to the ability to form gels of various strengths, to show therapeutic and preventive properties. Cucurbita maxima pumpkin is considered as a source of natural and inexpensive pectin, as well as a functional food product for use in food and pharmaceutical preparations. The aim of the study was to identify the features of the accumulation of pectin substances in the most economically significant species of pumpkin C. maxima from the VIR collection. It was found that the studied varieties differ significantly in the amount of pectin substances. The content of pectins in the conditions of the North-West of Russia varied in the range from 0.59 to 4.24% (for absolutely dry matter). The content of soluble pectins was in the range of 0.24-1.36%. The level of protopectin accumulation, depending on the genotype and conditions of the growing season, was 0.35-3.37%. Sources of high content of soluble pectin and protopectin in pumpkin fruits have been identified for their further use in breeding, food and pharmaceutical industries.

Changes in fruit texture and cell structure of different pumpkin varieties (lines) during storage

After harvest, the pumpkin fruit has strong respiration and metabolic activities, which easily induce quality deterioration, shortening the storage period and shelf life, which affects the farmers' income. To understand the quality change mechanisms of pumpkins and extend the storage period, the fruit cell wall components, related enzyme activities, and fruit texture of Baimi No. 2, Baimi No. 3, Baimi No. 5, Baimi No. 10 and 2020-X1 pumpkin varieties (lines) were monitored during storage at 18 ± 2 °C after harvest.The pumpkin fruit texture was analyzed via the texture profile analysis (TPA) method, and the cell structure changes in peel and pulp cells were monitored using paraffin sections. The results revealed that the hardness, brittleness, viscosity, and elasticity of the five pumpkin fruits were decreased, while the adhesiveness, cohesion, recovery, and chewiness were first increased before decreasing with the prolongation of storage time. In addition, the protopectin, cellulose, and hemicellulose contents were decreased, while the soluble pectin content was increased. In addition, the polygalacturonase activity was increased, and the β-galactosidase, Cx cellulase, and pectinesterase activities were decreased. The cell wall components and enzymatic activities in Baimi No. 10 had minor changes, implying it is storage resistant. In addition, its peel and pulp cells were small and tightly arranged, with minor cellular changes. The peel cells were nearly square, and the pulp cells nearly round, rendering this variety more storable. Baimi No. 5 pulp cells were large and loosely arranged, with large intercellular spaces, rendering this variety short-lived.

Integrated analysis of postharvest storage characteristics of seven apple cultivars and transcriptome data identifies MdBBX25 as a negative regulator of fruit softening during storage in apples

Apple is classified as a climacteric fruit, characterized by a rapid surge in ethylene levels at the onset of ripening. However, there is significant variation in the degree and timing of ripening and softening among different apple cultivars. Understanding the molecular mechanisms underlying fruit softening and the associated changes in cell wall integrity is crucial for improving fruit quality and extending shelf life. In this study, we conducted a comparative analysis of fruit firmness and ethylene production among seven apple cultivars with different softening patterns during storage. We also examined the expression patterns of genes and enzyme activities involved in cell wall metabolism. Our results showed that fruit firmness was negatively correlated with ethylene production rate, respiration rate, soluble pectin content, cellulase activity, polygalacturonase activity, and β-glucosidase activity, while it was positively correlated with protopectin content and cellulose content. Furthermore, we identified a BBX transcription factor gene, MdBBX25, that was negatively correlated with fruit softening during storage. Overexpression of MdBBX25 resulted in delayed fruit softening by suppressing ethylene biosynthesis and cell wall-related genes, whereas silencing of MdBBX25 accelerated fruit softening by promoting ethylene biosynthesis and cell wall-related genes in apple. Our findings provide insights into the role of MdBBX25 as a negative regulator of fruit softening through the modulation of ethylene biosynthesis and cell wall degradation during storage.

Melatonin treatment inhibits mango fruit (Cv. ‘Guiqi’) softening by maintaining cell wall and reactive oxygen metabolisms during cold storage

Mango fruit (Mangifera indica L, cv. ‘Guiqi’) was treated with melatonin (1 mM) to explore the changing mechanisms in fruit softening and to examine the effects of melatonin on the interaction between the cell wall and reactive oxygen metabolisms subjected to cold storage. The results depicted that compared to control, melatonin treatment (1) improved storage life by maintaining the higher ascorbic acid (AsA) and reduced glutathione (GSH) contents, as well as maintained higher insoluble pectin, hemicellulose, and cellulose contents, and lower soluble pectin content of ‘Guiqi’ mango fruit. (2) Delayed fruit softening by maintaining higher firmness and suppressing the activities of polygalacturonase (PG), pectin methyl esterase (PME), cellulase (Cx), and β-glucosidase (β-glu); and cell wall degrading genes (MiPG14, MiPME, MiCel, and Miβ-glu). (3) Enhanced storage quality by inhibiting decay incidence, respiration rate, and weight loss rate; increased activity of glutathione reductase (GR) and inhibits reactive oxygen species (ROS) metabolites at cold storage. These results indicate that exogenous melatonin could delay mango fruit softening by maintaining cell wall metabolism, inhibiting ROS metabolites (O2.- and H2O2) accumulation via enhancement of non-enzymatic (AsA and GSH contents) and enzymatic (GR activity) antioxidants, and thus maintaining quality and improved storage life.

Comparison of cell wall changes of two different types of apple cultivars during fruit development and ripening

Fruit development and ripening is a complex procedure (Malus×domestica Borkh.) and can be caused by various factors such as cell structure, cell wall components, and cell wall hydrolytic enzymes. In our study, we focused on the variations in fruit firmness, cell wall morphology and components, the activity of cell wall hydrolytic enzymes and the expression patterns of associated genes during fruit development in two different types of apple cultivars, the hard-crisp cultivar and the loose-crisp cultivar. In this paper, the aim was to find out the causes of the texture variations between the different type cultivars. Cell wall materials (CWMs), hemicellulose and cellulose content were strongly associated with variations in fruit firmness during the fruit development. The content of water soluble pectin (WSP) and chelator soluble pectin (CSP) gradually increased, while the content of ionic soluble pectin (ISP) showed inconsistent trends in the four cultivars. The activities of polygalacturonase (PG), β-galactosidase (β-gal), cellulase (CEL), and pectate lyase (PL) gradually increased in four cultivars. And the activities of PG, β-gal, and CEL were higher in ‘Fuji’ and ‘Honeycrisp’ fruit with the fruit development, while the activity of PL of ‘Fuji’ and ‘Honeycrisp’ was lower than that of ‘ENVY’ and ‘Modi’. Both four cultivars of fruit cells progressively became bigger as the fruit expanded, with looser cell arrangements and larger cell gaps. According to the qRT-PCR, the relative expression levels of MdACO and Mdβ-gal were notably enhanced. Our study showed that there were large differences in the content of ISP and hemicellulose, the activity of PL and the relative expression of Mdβ-gal between two different types of apple cultivars, and these differences might be responsible for the variations in the texture of the four cultivars.

Participation of FaTRAB1 Transcription Factor in the Regulation of FaMADS1 Involved in ABA-Dependent Ripening of Strawberry Fruit.

Abscisic acid (ABA) plays a crucial role in regulating the ripening of non-climacteric strawberry fruit. In the present study, ABA was confirmed to promote strawberry ripening and induce the down-regulation of FaMADS1. The transient silence of FaMADS1 in strawberries promoted fruit ripening and induced the content of anthocyanin and soluble pectin but reduced firmness and protopectin through a tobacco rattle virus-induced gene silencing technique. In parallel with the accelerated ripening, the genes were significantly induced in the transiently modified fruit, including anthocyanin-related PAL6, C4H, 4CL, DFR, and UFGT, softening-related PL and XTH, and aroma-related QR and AAT2. In addition, the interaction between FaMADS1 and ABA-related transcription factors was researched. Yeast one-hybrid analysis indicated that the FaMADS1 promoter could interact with FaABI5-5, FaTRAB1, and FaABI5. Furthermore, dual-luciferase assay suggested that FaTRAB1 could actively bind with the FaMADS1 promoter, resulting in the decreased expression of FaMADS1. In brief, these results suggest that the ABA-dependent ripening of strawberry fruit was probably inhibited through inhibiting FaMADS1 expression by the active binding of transcript FaTRAB1 with the FaMADS1 promoter.

Comparative Study on the Influence of Various Drying Techniques on Drying Characteristics and Physicochemical Quality of Garlic Slices.

Effects of vacuum freeze drying (VFD), air impingement drying (AID), hot air drying based on temperature and humidity control (TH-HAD), pulsed vacuum drying (PVD), and medium- and short-wave infrared radiation drying (MSIRD) on the drying characteristics and physicochemical properties of garlic slices were investigated in the current work. Based on the experimental results, the Weibull model fitted the experimental results better (R2 > 0.99) than the Wang and Singh model. Samples dried with PVD showed the smallest color difference (ΔE*), better rehydration capacity and desirable reducing sugar content. In response to thermal effects and pressure pulsations, the cell walls gradually degraded, and the cell and organelle membranes ruptured. The allicin and soluble pectin contents of garlic slices treated with PVD were higher by 8.0-252.3% and 49.5-92.2%, respectively, compared to those of the samples dried by other techniques. VFD maintained a complete garlic slice structure with the minimum shrinkage and the best appearance. The MSIRD process produced the densest structure, and caused an additional loss of color and phytochemical contents. The findings in current work implied that PVD could be a promising drying technique for garlic slices.

Вплив овочевих пюре різних способів оброблення на органолептичні та фізико-хімічні показники морозива молочного

The purpose of the research is the scientific substantiation of the effect of vegetables with an increased content of soluble pectin on the quality indicators of low-calorie milk ice cream technology. The object of the research is low-calorie milk ice cream technology. The technological and functional properties of pectin-containing purées from vegetables (carrots, beets, tomatoes, zucchini and broccoli) as part of ice cream with their varied content in the range from 10 to 35% were studied. Sensory indicators, mass fraction of soluble pectin, water activity, active acidity, overrun and resistance to melting were chosen as the quality criteria of the obtained ice cream samples with vegetables. A higher yield of soluble pectin was found in fermented vegetable purées compared to purées subjected to thermal-acid treatment. It was found that fermentation and thermal-acid treatment of purée reduce the water activity in vegetables due to the increased content of soluble pectin. It was proved that the solids of vegetables increase the resistance to melting of ice cream. Based on the set of quality indicators of ice cream samples with vegetables, it was determined that vegetable purées from carrots, beets and zucchini have the highest technological activity, broccoli purée is a bit lower, and tomato purée is the lowest. Based on the comparative analysis of the research results, recommendations were developed for the preparation of basic recipes of ice cream with vegetables in the ranges of their content for the enzymatic processing method: carrots — 20—25%, beets — 15—20%, zucchini — 20—30%, broccoli — 15—20% and tomatoes — 25—30%; for thermo-acid processing: carrots — 15—20%, beets — 10—15%, zucchini — 15—20%, broccoli — 10—15% and tomatoes —20—25%. The introduction of vegetable purees in a lower amount than the recommended values gives the ice cream samples unexpressed sensory indicators, while exceeding the norms leads to uncharacteristic taste, aroma and consistency of ice cream. Carrot, beetroot and zucchini purée of various pretreatment methods can be used as separate vegetable multifunctional fillers, and broccoli and tomato purée is recommended to be used in combination with other vegetables

Diversity of Fruit Quality in Astringent and Non−Astringent Persimmon Fruit Germplasm

Persimmon (Diospyros kaki Thunb.) is an economically important tree with a long history of cultivation in China. So far, a total of approximately 1000 varieties have been found in China. To systematically evaluate the diversity of persimmon fruit quality, 22 quality measures of appearance, intrinsic, and sensory quality were evaluated using 61 typical persimmon fruit. According to the findings, the coefficient of variation (CV) of 15 appearance and intrinsic quality index values ranged from 13.81% (fruit shape index) to 165.80% (firmness), and the CV values of 7 intrinsic quality attributes were all higher than 50%, with the CV of total polyphenols and ironic soluble pectin contents (ISP) being as high as 159.82% and 143.80%, respectively. These findings showed that several persimmon germplasm resources had a highly diverse range of fruit quality, wide variation, and distribution. Insoluble tannin and soluble sugar were shown to have a substantial positive correlation with the sensory flavor indexes (p < 0.05), indicating their significance in influencing the flavor quality of persimmon fruit. Cluster analysis was performed utilizing 15 indexes of appearance, intrinsic quality, and 7 indexes of sensory quality. The samples were divided into two groups: group I consisted of 52 pollination−constant and astringent (PCA) and 1 pollination−-variant astringent (PVA) persimmon resources, and group II consisted of 6 pollination−constant non−astringent (PCNA) and 2 pollination−variant non−astringent (PVNA) persimmon resources. The results were consistent with the classification based on the mode of astringency loss, indicating that there was a significant difference in the quality of astringent and non−astringent persimmon fruit. This study provides theoretical references for the development and application of persimmon germplasm resources.

Transcriptomic and physiological analysis reveals the possible mechanism of ultrasound inhibiting strawberry (Fragaria × ananassa Duch.) postharvest softening.

Ultrasound effectively inhibited strawberry softening but the mechanism was not clear. In this study, physical data including firmness, soluble pectin (SP) contents, pectin esterase (PE), polygalacturonase (PG) activity and transcriptome sequencing data were analyzed to explore the mechanism of strawberry response to ultrasonic treatment. After 24 days storage, the firmness reduction rate and soluble contents (SP) increased rate of the strawberry treated with ultrasound (25 kHz, 0.15 W/cm2) for 3 min decreased 41.70 and 63.12% compared with the control, respectively. While the PG and PE enzyme activities of ultrasound-treated strawberries were significantly lower than control after storage for 18 days. A total of 1,905 diferentially expressed genes (DEGs) were identified between ultrasound-treated and control, with 714 genes upregulated and 1,254 genes downregulated, including 56 genes in reactive oxygen species (ROS), auxin (AUX), ethylene (ETH) and jasmonic acid (JA) signaling pathways. At 0 h, 15 genes including LOX, JMT, ARP, SKP, SAUR, IAA, ARF, and LAX were significantly upregulated compared with the control group, which means reactive oxygen specie, auxin, ethylene and jasmonic acid-mediated signaling pathway respond to ultrasound immediately. ERF109, ERF110, and ACS1_2_6 downregulated before 2 days storage indicated ethylene signaling pathway was inhibited, while after 2 days, 9 genes including ERF027, ERF109, and ERF110 were significantly upregulated indicating that the response of the ethylene signaling pathway was lagging. Therefore, in strawberry ultrasound enhanced ROS scavenging and activated JA biosynthesis, which acts as a signal for delaying the activation of ET signaling pathway, thus suppressing the activity of pectin-degrading enzymes PE and PG, and ultimately inhibiting postharvest softening.

Effect of ozone treatment on lignification and postharvest quality of water bamboo shoots

AbstractOzone treatment is a useful approach to maintain postharvest quality for various fruits and vegetables. In this study, the effects of ozone fumigation on lignification and postharvest quality changes in water bamboo shoots were investigated. Water bamboo shoots were respectively treated with ozone at the concentrations of 0 (control), 3, 6, 9, and 12 µl L−1, packaged in polyethylene packing bag and stored at 2 ± 1°C for 60 days. The results showed that ozone treatment maintained the lightness, whiteness index values and retarded the lignification during storage. Water bamboo shoots treated with 9 µl L−1 ozone showed the best fruit quality and the least lignification. Ozone treatment also slowed the decrease of soluble pectin content and cellulose accumulation by inhibiting the activities of cellulase (Cx) and polygalacturonase. In addition, ozone treatment also protected cell ultrastructure. Ozone treatment could be a potential alternative for inhibiting lignification and delaying quality deterioration of water bamboo shoots during storage.

Receptor-like kinase HAESA-like 1 positively regulates seed longevity in Arabidopsis.

Based on the phenotypic, physiological and transcriptomic analysis, receptor-like kinase HAESA-like 1 was demonstrated to positively affect seed longevity in Arabidopsis. Seed longevity is very important for both genetic resource conservation and crop production. Receptor-like kinases (RLKs) are widely involved in plant growth, development and stress responses. However, the role of most RLKs, especially in seed longevity, is largely unknown. In this study, we report that Arabidopsis HAESA-like 1 (AtHSL1) positively regulated seed longevity. Disruption of HSL1 significantly decreased the germination rate to 50% at 7days after cold stratification (DAC), compared with that of the wild type (93.5% at 7 DAC), after accelerated aging treatment. Expression of the HSL1 gene in hsl1 basically restored the defective phenotype (86.3%), while HSL1-overexpressing lines (98.3%) displayed slower accelerated aging than WT (93.5%). GUS staining revealed HSL1 was highly expressed universally, especially in young seedlings, mature seeds and embryos of imbibed seeds, and its expression could be induced by accelerated aging. No difference in the dyeing color and area of mucilage were identified between WT and hsl1. The soluble pectin content also was not different, while the adherent pectin content was significantly increased in hsl1. Global transcriptomics revealed that disruption of HSL1 mainly downregulated genes involved in trehalose synthesis, nucleotide sugar metabolism and protection and repair mechanisms. Therefore, an increase in adherent pectin content and downregulation of genes involved in trehalose synthesis may be the main reasons for decreasing seed longevity owing to disruption of HSL1 in Arabidopsis. Our work provides valuable information for understanding the function and mechanism of a receptor-like kinase, AtHSL1, in seed longevity.

Co-Application of 1-MCP and Laser Microporous Plastic Bag Packaging Maintains Postharvest Quality and Extends the Shelf-Life of Honey Peach Fruit.

Honey peach (Prunus persica L.) is highly nutritious; it is an excellent source of sugars, proteins, amino acids, vitamins, and mineral elements. However, it is a perishable climacteric fruit that is difficult to preserve. In this study, “Feicheng” honey peach fruit was used as a test material to investigate the synergistic preservation effect of 1-methylcyclopropene (1-MCP) and laser microporous film (LMF). The peach fruits were fumigated for 24 h with 2 μL L−1 1-MCP, then packed in LMF. In comparison with the control treatment, 1-MCP + LMF treatment markedly decreased the respiration rate, weight loss, and rot rate of peach fruits. Moreover, the combination of 1-MCP and LMF suppressed the increase in soluble solids (SS) and reducing sugars (RS), as well as the decrease in titratable acid (TA) and ascorbic acid (AsA). The combined application also maintained a high protopectin content and low soluble pectin content; it reduced the accumulation of superoxide anions (O2−) and hydrogen peroxide (H2O2). Except in a few samples, the catalase (CAT) and ascorbate peroxidase (APX) activities were higher when treated by 1-MCP + LMF. Conversely, the phenylalanine deaminase (PAL), peroxidase (POD), lipase, lipoxygenase (LOX), polygalacturonase (PG), β-glucosidase, and cellulase (Cx) activities were lower than in the control. Furthermore, 1-MCP + LMF treatment reduced the relative abundances of dominant pathogenic fungi (e.g., Streptomyces, Stachybotrys, and Issa sp.). The combined treatment improved the relative abundances of antagonistic fungi (e.g., Aureobasidium and Holtermanniella). The results indicated that the co-application of 1-MCP and LMF markedly reduced weight loss and spoilage, delayed the decline of nutritional quality, and inhibited the physiological and biochemical metabolic activities of peach during storage. These changes extended its shelf-life to 28 days at 5 °C. The results provide a reference for the commercial application of this technology.