Cell Wall Polysaccharide Content Research Articles

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.

Helium Cold Atmospheric Plasma Causes Morphological and Biochemical Alterations in Candida albicans Cells

(1) Background: Previous studies reported the promising inhibitory effect of cold atmospheric plasma (CAP) on Candida albicans. However, the exact mechanisms of CAP’s action on the fungal cell are still poorly understood. This study aims to elucidate the CAP effect on C. albicans cell wall, by evaluating the alterations on its structure and biochemical composition; (2) Methods: C. albicans cells treated with Helium-CAP were analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) in order to detect morphological, topographic and biochemical changes in the fungal cell wall. Cells treated with caspofungin were also analyzed for comparative purposes; (3) Results: Expressive morphological and topographic changes, such as increased roughness and shape modification, were observed in the cells after CAP exposure. The alterations detected were similar to those observed after the treatment with caspofungin. The main biochemical changes occurred in polysaccharides content, and an overall decrease in glucans and an increase in chitin synthesis were detected; (4) Conclusions: Helium-CAP caused morphological and topographic alterations in C. albicans cells and affected the cell wall polysaccharide content.

1-MCP application in ‘Xuxiang’ kiwifruit at appropriate firmness avoids hard-core and prolongs the shelf life

The lack of synchrony in softening among the tissue zones and the increase in the production of autocatalytic ethylene lead to the hard-core and a short eating window in ready-to-eat kiwifruit. The present study analyzed the differences between the outer pericarp and the core during ripening to identify the cause of hard-core in ‘Xuxiang’ kiwifruit and aimed to maintain a soft texture and extend the eating window of ready-to-eat kiwifruit using 1-methylcyclopropene (1-MCP). Initial analysis showed that the outer pericarp had a few small spherical cells and many elongated cells, while the core had large homogeneous parenchyma cells. The core maintained higher firmness and cell wall polysaccharide content than the outer pericarp. During ripening, the pericarp followed a sigmoidal trend in softening, while the core followed a linear trend. We also found that the outer pericarp preceded the core in expressing the cell wall degradation-related and ethylene biosynthesis-related genes (AcXET1, AcEXP1, AcPG, AcPL2, AcACS1, and AcACO2). Moreover, the increase in ethylene production was highly correlated with the decrease in core firmness. These differences between the outer pericarp and the core probably led to the hard-core in kiwifruit. Subsequent texture analysis and sensory evaluation revealed 75–100 N as the acceptable core firmness limit for ‘Xuxiang’ kiwifruit. The fruit treatment experiments based on these observations showed that applying 1-MCP on ready-to-eat ‘Xuxiang’ kiwifruit at ∼12 N firmness resulted in best preservation, with an extra 15 d of shelf life and an acceptable core firmness. In conclusion, these findings suggest that treating ‘Xuxiang’ kiwifruit at ∼12 N firmness after harvest with 1-MCP will help avoid hard-core and prolong the eating window, improving consumer acceptance.

Cell wall polysaccharide and glycoprotein content tracks growth-form diversity and an aridity gradient in the leaf-succulent genus Crassula.

Cell wall traits are believed to be a key component of the succulent syndrome, an adaptive syndrome to drought, yet the variability of such traits remains largely unknown. In this study, we surveyed the leaf polysaccharide and glycoprotein composition in a wide sampling of Crassula species that occur naturally along an aridity gradient in southern Africa, and we interpreted its adaptive significance in relation to growth form and arid adaptation. To study the glycomic diversity, we sampled leaf material from 56 Crassula taxa and performed comprehensive microarray polymer profiling to obtain the relative content of cell wall polysaccharides and glycoproteins. This analysis was complemented by the determination of monosaccharide composition and immunolocalization in leaf sections using glycan-targeting antibodies. We found that compact and non-compact Crassula species occupy distinct phenotypic spaces in terms of leaf glycomics, particularly in regard to rhamnogalacturonan I, its arabinan side chains, and arabinogalactan proteins (AGPs). Moreover, these cell wall components also correlated positively with increasing aridity, which suggests that they are likely advantageous in terms of arid adaptation. These differences point to compact Crassula species having more elastic cell walls with plasticizing properties, which can be interpreted as an adaptation toward increased drought resistance. Furthermore, we report an intracellular pool of AGPs associated with oil bodies and calcium oxalate crystals, which could be a peculiarity of Crassula and could be linked to increased drought resistance. Our results indicate that glycomics may be underlying arid adaptation and drought resistance in succulent plants.

Abscisic acid (ABA) alleviates cadmium toxicity by enhancing the adsorption of cadmium to root cell walls and inducing antioxidant defense system of Cosmos bipinnatus

Cadmium (Cd) pollution is a global problem affecting soil ecology and plant growth. Abscisic acid (ABA) acts as a growth and stress hormone, regulates cell wall synthesis, and plays an important role in plant responses to stress. There are few studies on the mechanisms behind abscisic acid alleviation of cadmium stress in Cosmos bipinnatus, especially in regards to regulation of the root cell wall. This study examined the effects of different concentrations of abscisic acid at different concentrations of cadmium stress. Through adding 5 μmol/L and 30 μmol/L cadmium, followed by spraying 10 μmol/L and 40 μmol/L ABA in a hydroponic experiment, it was found that under two concentrations of cadmium stress, low concentration of ABA improved root cell wall polysaccharide, Cd, and uronic acid content. Especially in pectin, after the application of low concentration ABA, the cadmium concentration was significantly increased by 1.5 times and 1.2 times compared with the Cd concentration under Cd5 and Cd30 treatment alone, respectively. Fourier-Transform Infrared spectroscopy (FTIR) demonstrated that cell wall functional groups such as -OH and -COOH were increased with exposure to ABA. Additionally, the exogenous ABA also increased expression of three kinds of antioxidant enzymes and plant antioxidants. The results of this study suggest that ABA could reduce Cd stress by increasing Cd accumulation, promoting Cd adsorption on the root cell wall, and activating protective mechanisms. This result could help promote application of C. bipinnatus for phytostabilization of cadmium-contaminated soil.

Post-harvest ripening affects drying behavior, antioxidant capacity and flavor release of peach via alteration of cell wall polysaccharides content and nanostructures, water distribution and status

Effect of post-harvest ripening on cell wall polysaccharides nanostructures, water status, physiochemical properties of peaches and drying behavior under hot air-infrared drying was evaluated. Results showed that the content of water soluble pectins (WSP) increased by 94 %, while the contents of chelate-soluble pectins (CSP), Na2CO3-soluble pectins (NSP) and hemicelluloses (HE) decreased during post-harvest ripening by 60 %, 43 %, and 61 %, respectively. The drying time increased from 3.5 to 5.5 h when the post-harvest time increased from 0 to 6 days. Atomic force microscope analysis showed that depolymerization of hemicelluloses and pectin occurred during post-harvest ripening. Time Domain -NMR observations indicated that reorganization of cell wall polysaccharides nanostructure changed water spatial distribution and cell internal structure, facilitated moisture migration, and affected antioxidant capacity of peaches during drying. This leads to the redistribution of flavor substances (heptanal, n-nonanal dimer and n-nonanal monomer). The current work elucidates the effect of post-harvest ripening on the physiochemical properties and drying behavior of peaches.

Melatonin Alleviates Chromium Toxicity in Maize by Modulation of Cell Wall Polysaccharides Biosynthesis, Glutathione Metabolism, and Antioxidant Capacity.

Melatonin, a pleiotropic regulatory molecule, is involved in the defense against heavy metal stress. Here, we used a combined transcriptomic and physiological approach to investigate the underlying mechanism of melatonin in mitigating chromium (Cr) toxicity in Zea mays L. Maize plants were treated with either melatonin (10, 25, 50 and 100 μM) or water and exposed to 100 μM K2Cr2O7 for seven days. We showed that melatonin treatment significantly decreased the Cr content in leaves. However, the Cr content in the roots was not affected by melatonin. Analyses of RNA sequencing, enzyme activities, and metabolite contents showed that melatonin affected cell wall polysaccharide biosynthesis, glutathione (GSH) metabolism, and redox homeostasis. During Cr stress, melatonin treatment increased cell wall polysaccharide contents, thereby retaining more Cr in the cell wall. Meanwhile, melatonin improved the GSH and phytochelatin contents to chelate Cr, and the chelated complexes were then transported to the vacuoles for sequestration. Furthermore, melatonin mitigated Cr-induced oxidative stress by enhancing the capacity of enzymatic and non-enzymatic antioxidants. Moreover, melatonin biosynthesis-defective mutants exhibited decreased Cr stress resistance, which was related to lower pectin, hemicellulose 1, and hemicellulose 2 than wild-type plants. These results suggest that melatonin alleviates Cr toxicity in maize by promoting Cr sequestration, re-establishing redox homeostasis, and inhibiting Cr transport from the root to the shoot.

Involvement of lignin deposition and cell wall degradation in stem senescence of Chinese flowering cabbage during storage

Chinese flowering cabbage is susceptible to leaf yellowing, however, little is known about stem senescence after harvest. Herein, changes in the microstructures, lignin and cell wall polysaccharide contents, and expression of their corresponding genes during the stem senescence of Chinese flowering cabbage were investigated. Anatomical and chemical analyses revealed that an increase in cell wall thickness was accompanied by lignin deposition around the vascular cells in the stem. Concurrently, the collapse of parenchyma cells developed gradually, which was probably related to the degradation of cell wall polysaccharides including pectin, hemicellulose, and cellulose, among others. The outer stem tissues, including epidermal cells to vascular cells, could be directly peeled, and the middle of the stem was found to contain prominent parenchyma cells as pith tissues. Activity of lignin biosynthesis-related enzymes of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), and peroxidase (POD), and the expression of their corresponding genes BrPAL2/3/6, Br4CL1/4, BrCAD2/4/5/11, and BrPOD31/37 were higher in outer peeled tissues than in pith tissues. The enzyme activity of polygalacturonase and pectin methylesterase, and expression levels of the polysaccharide degradation-related genes BrXET2/3, BrCEL3, and BrMAN1/5 were higher in pith than in outer peeled tissues. These results suggest that lignin deposition around the vascular tissue, and cell wall degradation in pith tissues are involved in the stem senescence of Chinese flowering cabbage after harvest.

硼添加对铝胁迫栝楼生长和生理的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 硼添加对铝胁迫栝楼生长和生理的影响 DOI: 10.5846/stxb202202220419 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（32001224，41702181）；2021年国家级大学生创新创业训练计划（202110345017） Effects of exogenous boron on growth and physiology of Trichosanthes kirilowii Maxim. under aluminum stress Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)，the 2021 National Undergraduate Training Program for Innovation and Entrepreneurship 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为揭示硼对缓解栝楼（Trichosanthes kirilowii Maxim.）铝（Aluminum）毒害的生理机制，以耐铝性强的安国栝楼和耐铝性弱的浦江栝楼为材料，研究了50 μmol/L硼酸（H3BO3）对300 μmol/L Al3+胁迫下栝楼幼苗生长、铝积累、抗氧化能力和细胞壁组分的影响。结果表明：铝胁迫下，植株的根长、株高、鲜重和干重降低，超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性受到显著抑制，安国栝楼、浦江栝楼根尖丙二醛（MDA）含量分别增加256.1%、278.2%，细胞壁多糖含量、果胶甲酯酶（PME）活性、根尖铝积累量显著提高，果胶甲基酯化度（DM）和3-脱氧-D-甘露-辛酮糖酸（KDO）含量降低。外源硼可以缓解铝胁迫对栝楼幼苗生长的抑制作用，安国与浦江栝楼的抗氧化酶活性显著提升，MDA含量、细胞壁多糖含量、PME酶活性均降低，安国栝楼果胶DM值恢复至正常水平的91.5%，浦江栝楼KDO含量较单铝处理组上升52.0%，活性铝结合位点减少，有效降低了根尖铝含量并维持其形态结构。因此，硼信号能通过调节细胞壁多糖组分且稳定其网格结构，减少根尖对铝的吸收，同时增强抗氧化酶活性，缓解铝胁迫导致栝楼幼苗生长中的次生氧化胁迫，提高栝楼幼苗对铝毒环境的耐受性，且对耐铝性强的安国栝楼作用效果较好。研究结果可为改良酸铝胁迫下作物的生长环境提供理论指导。 Abstract:Aluminum toxicity, a major abiotic stress that inhibits plant growth and development, has become one of the main factors reducing agricultural yield. To reveal the physiological mechanism of boron on alleviating aluminum toxicity of Trichosanthes kirilowii Maxim., seedlings from Anguo (with strong Al-tolerance) and Pujiang (with weak Al-tolerance) varieties of T. kirilowii were selected for water culture experiments and the effects of boron treatment (50 μmol/L) on varieties' growth, aluminum accumulation, antioxidant capacity, and cell wall components under aluminum stress (300 μmol/L) were studied. The results showed that 300 μmol/L Al3+ stress inhibited the root length, plant height, fresh weight, and dry weight of the plant. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were significantly decreased, and the content of malondialdehyde (MDA) in root tip of T. kirilowii in Anguo and Pujiang varieties increased by 256.1% and 278.2%, respectively. Aluminum stress also significantly enhanced the content of cell wall polysaccharide, pectin methylesterase (PME) activity, and root tip aluminum accumulation. However, the degree of pectin methyl-esterification (DM) and the content of 3-deoxy-d-mannose-octanoic acid (KDO) were strongly inhibited. Exogenous boron could alleviate the inhibitory effect of aluminum stress on the growth of T. kirilowii seedlings. The antioxidant enzyme activities of T. kirilowii in Anguo and Pujiang varieties were increased significantly. The MDA content, cell wall polysaccharide content, and PME enzyme activity were decreased. In addition, the pectin DM value of Trichosanthes in Anguo variety returned to 91.5% of the normal level, and the KDO content of T. kirilowii in Pujiang variety increased by 52.0% compared with that in the single aluminum treatment group. As a result, the active aluminum binding sites decreased, effectively reducing the aluminum content in the root tip and maintaining its morphological structure. Therefore, boron improved the tolerance of T. kirilowii seedlings to aluminum toxic environment by regulating the polysaccharide components of cell wall and stabilizing its grid structure to reduce the absorption of aluminum by root tips, and enhancing the activity of antioxidant enzymes to alleviate the secondary oxidative stress in the growth of T. kirilowii seedlings, which has a better effect on Anguo variety with stronger tolerance to aluminum toxicity. The research in this paper can provide theoretical guidance for improving the environment for crop growth under acid-aluminum stress. 参考文献 相似文献 引证文献

Comprehensive analysis reveals the underlying mechanism of arbuscular mycorrhizal fungi in kenaf cadmium stress alleviation

Soil Cadmium (Cd) contamination has become a severe environmental problem around the world. Kenaf has great potential for utilization and phytoremediation of soil contaminated with heavy metal. Arbuscular mycorrhizal fungi (AMF) can help plants alleviate Cd stress, but the underlying mechanism remains completely unknown. In this study, kenaf was inoculated or not inoculated with AMF at cadmium concentrations of 10 mg kg−1 and 50 mg kg−1 from the seedling stage to the vigorous growth stage. The results showed that AMF symbionts improved nutrient transport efficiency and significantly improved plant growth. Additionally, AMF colonization increased cell wall polysaccharide content which help to bind Cd in the cell wall and reduced the transport of Cd to aboveground plant tissues. The increase in soil pH (6.9), total balcomycin and easily extractable balcomycin content facilitated the chelation of metal by mycorrhizal fungi and reduced the biological effectiveness of Cd. Furthermore, AMF upregulated the expression levels of key kenaf genes, such as Hc.GH3.1, Hc.AKR, and Hc.PHR1, which plays an important role in enhancing kenaf Cd tolerance. Our findings systematically revealed the mechanisms by which AMF responds to Cd stress in kenaf, inoculation of AMF with kenaf could be used to enhance the removal of Cd from soil pollution in mining areas by phytoremediation.

Effects of Elevated Aluminum Concentration and Distribution on Root Damage, Cell Wall Polysaccharides, and Nutrient Uptake in Different Tolerant Eucalyptus Clones.

Aluminized acidic soil can damage Eucalyptus roots and limit tree growth, hindering the productivity of Eucalyptus plantations. At present, the negative impacts of elevated aluminum (Al) on the cell morphology and cell wall properties of Eucalyptus root tip are still unclear. In order to investigate the responses of two different tolerant clones, Eucalyptus urophylla (G4) and Eucalyptus grandis × Eucalyptus urophylla (G9), to Al toxicity, seedling roots were treated hydroponically with an Al solution, and the polysaccharide content in the root tip cell wall and the characteristics of programmed cell death were studied. The results show that the distribution of Al was similar in both clones, although G9 was found to be more tolerant to Al toxicity than G4. The Al3+ uptake of pectin in root tip cell walls was significantly higher in G4 than in G9. The root tip in G4 was obviously damaged, enlarged, thickened, and shorter; the root crown cells were cracked and fluffy; and the cell elongation area was squeezed. The lower cell wall polysaccharide content and PME activity may result in fewer carboxylic groups in the root tip cell wall to serve as Al-binding sites, which may explain the stronger Al resistance of G9 than G4. The uptake of nitrogen and potassium in G4 was significantly reduced after aluminum application and was lower than in G9. Al-resistant Eucalyptus clones may have synergistic pleiotropic effects in resisting high aluminum-low phosphorus stress, and maintaining higher nitrogen and potassium levels in roots may be an important mechanism for effectively alleviating Al toxicity.

Engineering sorghum for higher 4-hydroxybenzoic acid content

Engineering bioenergy crops to accumulate coproducts in planta can increase the value of lignocellulosic biomass and enable a sustainable bioeconomy. In this study, we engineered sorghum with a bacterial gene encoding a chorismate pyruvate-lyase (ubiC) to reroute the plastidial pool of chorismate from the shikimate pathway into the valuable compound 4-hydroxybenzoic acid (4-HBA). A gene encoding a feedback-resistant version of 3-deoxy-d-arabino-heptulonate-7-phosphate synthase (aroG) was also introduced in an attempt to increase the carbon flux through the shikimate pathway. At the full maturity and senesced stage, two independent lines that co-express ubiC and aroG produced 1.5 and 1.7 dw% of 4-HBA in biomass, which represents 36- and 40-fold increases compared to the titer measured in wildtype. The two transgenic lines showed no obvious phenotypes, growth defects, nor alteration of cell wall polysaccharide content when cultivated under controlled conditions. In the field, when harvested before grain maturity, transgenic lines contained 0.8 and 1.2 dw% of 4-HBA, which represent economically relevant titers based on recent technoeconomic analysis. Only a slight reduction (11–15%) in biomass yield was observed in transgenics grown under natural environment. This work provides the first metabolic engineering steps toward 4-HBA overproduction in the bioenergy crop sorghum to improve the economics of biorefineries by accumulating a value-added coproduct that can be recovered from biomass and provide an additional revenue stream.

Suppression of Cucumber Green Mottle Mosaic Virus Infection by Boron Application: From the Perspective of Nutrient Elements and Carbohydrates.

Cucumber green mottle mosaic virus (CGMMV) infection causes "blood flesh" symptoms in watermelon fruits, which severely reduces yield and edibleness. However, the growth of watermelon fruits is strongly associated with boron (B), a trace element for improving fruit quality. In this study, B-gradient hydroponic experiments (B concentration: 0, 2.86, and 5.72 mg·L-1 H3BO3) and foliar-spray experiments (B concentration: 30 and 300 mg·L-1 H3BO3) were performed. We found that the B-supplement could inhibit CGMMV infection and especially relieve "blood flesh" symptoms in watermelon fruits. The nutrient element, soluble sugar, and cell wall polysaccharide contents and their metabolism- and transport-related gene expressions were determined in leaves and fruits of the watermelons in B-gradient hydroponic and foliar-spray experiments. We found that the accumulation and metabolism of nutrients and carbohydrates in cells were disrupted by CGMMV infection; however, the B-supplement could restore and maintain their homeostasis. Additionally, we uncovered that NIP5;1 and SWEET4, induced by B-application with CGMMV infection, could majorly contribute to the resistance to CGMMV infection by regulating nutrient elements and carbohydrate homeostasis. These results provided a novel insight into the molecular mechanism of B-mediated CGMMV suppression and an efficient method of B-application for the improvement of watermelon quality after CGMMV infection.

Using brefeldin A to disrupt cell wall polysaccharide components in rice and nitric oxide to modify cell wall structure to change aluminum tolerance.

The components and structure of cell wall are closely correlated with aluminum (Al) toxicity and tolerance for plants. However, the cell wall assembly and function construction in response to Al is not known. Brefeldin A (BFA), a macrolide, is used to disrupt cell wall polysaccharide components, and nitric oxide (NO), a signal molecule, is used to modify the cell wall structure. Pretreatment with BFA accelerated Al accumulation in root tips and Al-induced inhibition of root growth of two rice genotypes of Nipponbare and Zhefu 802, and significantly decreased the cell wall polysaccharide content including pectin, hemicellulose 1, and hemicellulose 2, indicating that BFA inhibits the biosynthesis of components in the cell wall and makes the root cell wall lose the ability to resist Al. The addition of NO donor (SNP) significantly alleviated the toxic effects of Al on root growth, Al accumulation, and oxidative damage, and decreased the content of pectin polysaccharide and functional groups of hydroxyl, carboxyl, and amino in the cell wall via FTIR analysis, while had no significant effect on hemicellulose 1 and hemicellulose 2 content compared with Al treatment. Furthermore, NO didn't change the inhibition effect of BFA-induced cell wall polysaccharide biosynthesis and root growth. Taken together, BFA disrupts the integrity of cell wall and NO modifies partial cell wall composition and their functional groups, which change the Al tolerance in rice.

Gravimetric analysis of tomato stems in the perception of a gravitational signal

The dynamics of the content of various groups of cell wall polysaccharides in the cells of tomato stems during the development of the plant’s response to gravitational stimulation and phytohormonal treatment was studied. It has been shown that gravitational stimulation causes changes in the relative content of stem cell wall polysaccharides in the zone of gravitropic bending over a period of 3–6 hours. At the same time, predominantly multidirectional changes occur in the upper and lower halves of the stem, which ultimately leads to noticeable biochemical differences between the two parts of the stem, which allows it, in all likelihood, to bend due to an uneven growth of cells in different parts of the stem. Under the action of gravitational stimulation and epibrassinosteroid epine, changes in the polysaccharide composition appear earlier (already 1 hour after exposure) in time than with a single gravitational stimulation, and under the influence of ethephon and gravitational stimulation later (only from 6 hours of exposure).

Storage temperature effect on quality related with cell wall metabolism of shiitake mushrooms (Lentinula edodes) and its modeling

Fresh shiitake mushrooms (Lentinula edodes) are susceptible to temperature fluctuation, thus easy to soften. In this study, the effects of temperature during storage on the softening mechanism of postharvest shiitake mushrooms were studied. The firmness, cell wall polysaccharide contents, chitin and cellulose contents, cell wall degrading enzyme activities, and their gene expression levels were evaluated. The relationship between the indicators and the accumulated storage temperature was also analyzed. Results showed that decreasing firmness was concomitant with cell wall components reduction, the increase in enzymatic activities and gene expression levels. Increasing the storage temperature promoted these changes. Thus, cell wall polysaccharides modification induced by the cell wall degrading enzymes played a key role in the temperature-mediated softening mechanism of postharvest shiitake mushrooms. The firmness, 10 mol L-1 NaOH-soluble polysaccharide, total polysaccharide, chitin and cellulose contents, β-1,3-glucanase activity, expressions of Letlg1, Leglu1, Leexg1, Leexg2, Lepus30a and Lechi1 were fitted well with accumulated storage temperature, implying that they were related to the firmness loss and could describe the effects of storage temperature and time on softening process in shiitake mushrooms.

Short-chain aldehydes increase aluminum retention and sensitivity by enhancing cell wall polysaccharide contents and pectin demethylation in wheat seedlings

Upon environmental stimuli, aldehydes are generated downstream of reactive oxygen species and thereby contribute to severe cell damage. In this study, using two wheat genotypes differing in aluminum (Al) tolerance, we investigated the effects of lipid peroxidation-derived aldehydes on cell wall composition and subsequent Al-binding capacities. The spatial accumulation of Al along wheat roots was found to the generation of reactive aldehydes, which are highly localized to the apical regions of roots. Elimination of aldehydes by carnosine significantly reduced Al contents in root tips, with a concomitant alleviation of root growth inhibition. In contrast, root growth and Al accumulation were exacerbated by application of the short-chain aldehyde (E)−2-hexenal. We further confirmed that cell wall binding capacity, rather than malate efflux or pH alteration strategies, is associated with the aldehyde-induced accumulation of Al. Scavenging of lipid-derived aldehydes reduced Al accumulation in the pectin and hemicellulose 1 (HC1) fractions of root cell walls, whereas exposure to (E)−2-hexenal promoted a further accumulation of Al, particularly in the cell wall HC1 fraction of the Al-sensitive genotype. Different strategies were introduced by pectin and HC1 to accumulate Al in response to aldehydes in wheat roots. Accumulation in pectin is based on a reduction of methylation levels in response to elevated pectin methylesterase activity and gene expression, whereas that in HC1 is associated with an increase in polysaccharide contents. These findings indicate that aldehydes exacerbate Al phytotoxicity by enhancing Al retention in cell wall polysaccharides.

Lanthanum Promotes Bahiagrass (Paspalum notatum) Roots Growth by Improving Root Activity, Photosynthesis and Respiration

Lanthanum (La), one of the most active rare earth elements, promotes the growth of turfgrass roots. In this study, the mechanisms by which La influences bahiagrass (Paspalum notatum) growth were evaluated by the analyses of root growth, root activity, cell wall polysaccharide content, respiration intensity, ascorbic acid oxidase (AAO) and polyphenol oxidase (PPO) activity, the subcellular distribution of mitochondria, transcription in roots, photosynthetic properties, chlorophyll fluorescence parameters, and chlorophyll content. The application of 0.3 mM La3+ increased root activity, respiration intensity, AAO activity, and the number of mitochondria in the mature cells of bahiagrass roots. La could significantly improve the net photosynthetic rate, transpiration rate, and chlorophyll fluorescence of bahiagrass. Differentially expressed genes identified by high-throughput transcriptome sequencing were enriched for GO (Gene Ontology) terms related to energy metabolism and were involved in various KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, including oxidative phosphorylation, TCA (Tricarboxylic Acid) cycle, and sucrose metabolism. These findings indicate that La promotes bahiagrass root growth by improving root activity, photosynthesis, and respiration, which clarifies the mechanisms underlying the beneficial effects of La and provides a theoretical basis for its use in artificial grassland construction and ecological management projects.

Crosstalk between Yeast Cell Plasma Membrane Ergosterol Content and Cell Wall Stiffness under Acetic Acid Stress Involving Pdr18.

Acetic acid is a major inhibitory compound in several industrial bioprocesses, in particular in lignocellulosic yeast biorefineries. Cell envelope remodeling, involving cell wall and plasma membrane composition, structure and function, is among the mechanisms behind yeast adaptation and tolerance to stress. Pdr18 is a plasma membrane ABC transporter of the pleiotropic drug resistance family and a reported determinant of acetic acid tolerance mediating ergosterol transport. This study provides evidence for the impact of Pdr18 expression in yeast cell wall during adaptation to acetic acid stress. The time-course of acetic-acid-induced transcriptional activation of cell wall biosynthetic genes (FKS1, BGL2, CHS3, GAS1) and of increased cell wall stiffness and cell wall polysaccharide content in cells with the PDR18 deleted, compared to parental cells, is reported. Despite the robust and more intense adaptive response of the pdr18Δ population, the stress-induced increase of cell wall resistance to lyticase activity was below parental strain levels, and the duration of the period required for intracellular pH recovery from acidification and growth resumption was higher in the less tolerant pdr18Δ population. The ergosterol content, critical for plasma membrane stabilization, suffered a drastic reduction in the first hour of cultivation under acetic acid stress, especially in pdr18Δ cells. Results revealed a crosstalk between plasma membrane ergosterol content and cell wall biophysical properties, suggesting a coordinated response to counteract the deleterious effects of acetic acid.

Comparison of steaming and boiling of root vegetables for enhancing carbohydrate content and sensory profile

Root vegetables have unique techno-functional and nutritional properties however, their use in processed foods is limited to a few species, partially due to a lack of knowledge related to the impact of thermal treatments on the sensory properties. This study investigated the effect of steaming and boiling on the microstructure, mechanical properties, and sensory profile of three model root vegetables with distinct carbohydrate composition: Jerusalem artichoke ( Helianthus tuberosus L.), parsnip ( Pastinaca sativa ), and beetroot ( Beta vulgaris ). Thermally treated Jerusalem artichoke and parsnip showed higher content of cell wall polysaccharides, particularly β-glucans (e.g. cellulose) and pectic components, compared to raw. Steaming produced more cell shrinkage and loss of cell-cell adhesion than boiling, leading to softer vegetables. Processed beetroot showed loss of cell turgor and drastic softening but not clear changes in overall carbohydrate content. The scores for several flavour and in-mouth attributes were higher for steamed vegetables compared to boiled. Our results give insights on the processability of root vegetables towards products with enhanced sensory and nutritional properties. • Steaming and boiling increase dietary fibre in Jerusalem artichoke and parsnip. • Steamed vegetables are softer, have larger cell shrinkage and loss of cell adhesion. • Textural changes in processed beetroot are not related to total carbohydrates. • Flavour and in-mouth sensory attributes scores are higher for steamed vegetables. • Results give insights to use root vegetable pieces in processed foods.