Natural foods,such as whole pulses,are recommended in the dietary guidelines of the US and China.The plant cell wall structure in whole pulses has important implications for the nutritional functionalities of starch.I...Natural foods,such as whole pulses,are recommended in the dietary guidelines of the US and China.The plant cell wall structure in whole pulses has important implications for the nutritional functionalities of starch.In this study,garbanzo bean cells with varying degrees of cell wall integrity were subjected to dry heat treatment(DHT)and used to elucidate the food structure-starch digestion properties of pulse food.The morphological features suggested that all cell samples do not exhibit remarkable changes after being subjected to DHT.Molecular rearrangement and the crystallite disruption of starch granules entrapped in cells occurred during DHT as assessed by the crystal structure and thermal properties.DHT decreased the inhibitory effects of enzymes of both the soluble and insoluble components,but the digestion rate and extent of slightly and highly damaged cell samples did not exhibit significant differences compared with their native counterparts.We concluded that the starch digestion of pulse cotyledon cells is primarily determined by the intactness of the cellular structure.This study reveals the role of food structure on the ability to retain the desirable nutritional properties of starch after subjection to physical modification.展开更多
Phosphorus(P) starvation in rice facilitates the reutilization of root cell wall P by enhancing the pectin content. NaCl modulates pectin content, however, it is still unknown whether NaCl is also involved in the proc...Phosphorus(P) starvation in rice facilitates the reutilization of root cell wall P by enhancing the pectin content. NaCl modulates pectin content, however, it is still unknown whether NaCl is also involved in the process of pectin regulated cell wall P remobilization in rice under P starved conditions. In this study, we found that 10 mmol/L NaCl increased the shoot and root biomasses under P deficiency to a remarkable extent, in company with the elevated shoot and root soluble P contents in rice. Further analysis indicated that exogenous NaCl enhanced the root cell wall P mobilization by increasing the pectin methylesterase activity and uronic acid content in pectin suggesting the involvement of NaCl in the process of cell wall P reutilization in P starved rice roots. Additionally, exogenous NaCl up-regulated the expression of P transporter OsPT6, which was induced by P deficiency, suggesting that NaCl also facilitated the P translocation prominently from root to shoot in P starved rice. Moreover, exogenous abscisic acid(ABA) can reverse the NaCl-mediated mitigation under P deficiency, indicating the involvement of ABA in the NaCl regulated root cell wall P reutilization. Taken together, our results demonstrated that NaCl can activate the reutilization of root cell wall P in P starved rice, which is dependent on the ABA accumulation pathway.展开更多
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 focus...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.展开更多
Because plant mechanical strength influences plant growth and development,the regulatory mechanisms underlying cell-wall synthesis deserve investigation.Rice mutants are useful for such research.We have identified a n...Because plant mechanical strength influences plant growth and development,the regulatory mechanisms underlying cell-wall synthesis deserve investigation.Rice mutants are useful for such research.We have identified a novel brittle culm 25(bc25)mutant with reduced growth and partial sterility.BC25 encodes an UDP-glucuronic acid decarboxylase involved in cellulose synthesis and belongs to the UXS family.A single-nucleotide mutation in BC25 accounts for its altered cell morphology and cellwall composition.Transmission electron microscopy analysis showed that the thickness of the secondary cell wall was reduced in bc25.Monosaccharide analysis revealed significant increases in content of rhamnose and arabinose but not of other monosaccharides,indicating that BC25 was involved in xylose synthesis with some level of functional redundancy.Enzymatic assays suggested that BC25 functions with high activity to interconvert UDP-glucuronic acid(UDP-Glc A)and UDP-xylose.GUS staining showed that BC25 was ubiquitously expressed with higher expression in culm,root and sheath,in agreement with that shown by quantitative real-time(q RT)-PCR.RNA-seq further suggested that BC25 is involved in sugar metabolism.We conclude that BC25 strongly influences rice cell wall formation.展开更多
Plant cell elongation depends on well-defined gene regulations,adequate nutrients,and timely cell wall modifications.Anther size is positively correlated with the number and viability of pollen grains,while little is ...Plant cell elongation depends on well-defined gene regulations,adequate nutrients,and timely cell wall modifications.Anther size is positively correlated with the number and viability of pollen grains,while little is known about molecular mechanisms underlying anther cell elongation.Here,we found that properly activated cell elongation regulators at transcriptional levels in loss-of-function ZmMs33 mutant(ms33-6038)anthers failed to promote maize anther elongation.ZmMs33 deficiency disrupted metabolic homeostasis mainly by inhibiting both photosynthesis in anther endothecium and lipid accumulation in anther tapetum.Importantly,ms33-6038 anthers displayed ectopic,premature and excessive secondary cell wall thickening in anther middle layer,which constrained cell elongation structurally and blocked nutrient flows across different anther wall layers.The metabolic disorder was only found in ms33-6038 mutant rather than several representative male-sterility lines at transcriptional and post-translational levels.Collectively,the disordered metabolisms and blocked nutrient flows defeated the activated cell elongation regulators,and finally inhibited anther elongation and growth with a unique‘‘idling effect”in ms33-6038 mutant.展开更多
The cell wall composition and structure of the maize stalk directly affects its digestibility and in turn its feed value.Previous studies of stem quality have focused mostly on common maize germplasm,and few studies h...The cell wall composition and structure of the maize stalk directly affects its digestibility and in turn its feed value.Previous studies of stem quality have focused mostly on common maize germplasm,and few studies have focused on high-oil cultivars with high grain and straw quality.Investigation of the genetic basis of cell wall composition and digestibility of maize stalk using high-oil maize is desirable for improving maize forage quality.In the present study,a high-oil inbred line(By804)was crossed as male parent with the maize inbred line B73 to construct a population of 188 recombinant inbred lines(RILs).The phenotypes of six cell-wall-related traits were recorded,and QTL analysis was performed with a genetic map constructed with SNP markers.All traits were significantly correlated with one another and showed high broad-sense heritability.Of 20 QTLs mapped,the QTL associated with each trait explained 10.0%–41.1%of phenotypic variation.Approximately half of the QTL each explained over 10%of the phenotypic variation.These results provide a theoretical basis for improving maize forage quality by marker-assisted selection.展开更多
Cell wall architecture plays a key role in stalk strength and forage digestibility.Lignin,cellulose,and hemicellulose are the three main components of plant cell walls,and they can impact stalk quality by affecting th...Cell wall architecture plays a key role in stalk strength and forage digestibility.Lignin,cellulose,and hemicellulose are the three main components of plant cell walls,and they can impact stalk quality by affecting the structure and strength of the cell wall.To explore cell wall development during secondary cell wall lignification in maize stalks,conventional and conditional genetic mapping were used to identify the dynamic quantitative trait loci(QTLs)of the cell wall components and digestibility traits during five growth stages after silking.Acid detergent lignin(ADL),cellulose(CEL),acid detergent fiber(ADF),neutral detergent fiber(NDF),and in vitro dry matter digestibility(IVDMD)were evaluated in a maize recombinant inbred line(RIL)population.ADL,CEL,ADF,and NDF gradually increased from 10 to 40 days after silking(DAS),and then they decreased.IVDMD initially decreased until 40 DAS,and then it increased slightly.Seventytwo QTLs were identified for the five traits,and each accounted for 3.48–24.04%of the phenotypic variation.Six QTL hotspots were found,and they were localized in the 1.08,2.04,2.07,7.03,8.05,and 9.03 bins of the maize genome.Within the interval of the pleiotropic QTL identified in bin 1.08 of the maize genome,six genes associated with cell wall component biosynthesis were identified as potential candidate genes for stalk strength as well as cell wall-related traits.In addition,26 conditional QTLs were detected in the five stages for all of the investigated traits.Twenty-two of the 26 conditional QTLs were found at 30 DAS conditioned using the values of 20 DAS,and at 50 DAS conditioned using the values of 40 DAS.These results indicated that cell wall-related traits are regulated by many genes,which are specifically expressed at different stages after silking.Simultaneous improvements in both forage digestibility and lodging resistance could be achieved by pyramiding multiple beneficial QTL alleles identified in this study.展开更多
The plant cell wall is a complex 3D network composed of polysaccharides, lignin and proteins. The knowledge of the structure and content of each cell wall polymer is a prerequisite to understand their functions during...The plant cell wall is a complex 3D network composed of polysaccharides, lignin and proteins. The knowledge of the structure and content of each cell wall polymer is a prerequisite to understand their functions during plant development and adaptation but also to optimise their industrial applications. The analysis of cell wall compounds is complicated by their multiple molecular interactions. In this review, we present numerous methods to purify, characterise and quantify proteins, polysaccharides and lignin from the wall. Two kinds of approaches are detailed: the first presents in vitro methods which involve the breakdown of the molecular linkages between polymers thanking to chemical, physical and/or enzymatic treatments. The second approach describes in situ methods that allow the cell wall polymer characterisation thanking to many analytical techniques coupled with microscopy. If microscopy is the common point of all of them, their development is associated with improvement of analytical techniques, increasing their power of resolution.展开更多
The addition of p-coumaric acid (pCA) to lignin molecules is frequently found in members of the grass family. The role of this addition is not clearly understood, but is thought to potentially aid in the formation of ...The addition of p-coumaric acid (pCA) to lignin molecules is frequently found in members of the grass family. The role of this addition is not clearly understood, but is thought to potentially aid in the formation of syringyl-type lignin. This is because the incorporation is as a conjugate of pCA ester linked to sinapyl alcohol, a major component of lignin. The forage legume alfalfa (Medicago sativa L.) does not contain appreciable levels of pCA in its more heavily lignified stem tissues. The maize p-coumaryltransferase (pCAT) gene was used to transform alfalfa to determine its impact upon lignin composition and its potential to alter cell wall digestibility. A constitutive expression vector using the cassava vein mosaic virus (CsVMV) promoter was used to drive expression of maize pCAT in alfalfa. Expression of the pCAT transgene was detected in both leaves and stems. Though there was a range of pCAconcentration in transformed alfalfa stems (0.2 - 1.79 micrograms (μg)), this was a clear increase over bound pCA in control stems (0.15 - 0.2 mean = 0.17 micrograms (μg)). This did not lead to consistent responses concerning total lignin in the stem tissues. Leaf tissue, on the other hand, already has a relatively high level of pCA (0.85 - 1.2, mean = 0.99 micrograms (μg)) and those expressing pCAT gene showed on average a small increase, but there is a wide range of values among the transformants (0.38 - 1.55, mean = 1.06 micrograms (μg)). Lignin in leaves did not appear to be significantly impacted. However, incorporation of pCA into the wall appears to cause a shift in lignin composition. Testing the pCAT expressing stem cell walls for digestibility using a rumen in vitro system showed there was no change in the digestibility of the stem compared to empty vectors and control alfalfa stems. Although expression of pCAT gene in alfalfa changes the amount of wall bound pCA, it does not appear to change lignin levels or impact digestibility.展开更多
Diabetic foot ulcers are one of the most severe complications of diabetes that have imposed great financial and psychological burdens on diabetic patients.A Nocardia rubra cell wall skeleton(Nr-CWS)can be externally a...Diabetic foot ulcers are one of the most severe complications of diabetes that have imposed great financial and psychological burdens on diabetic patients.A Nocardia rubra cell wall skeleton(Nr-CWS)can be externally applied to accelerate wound healing.However,its clinical application has not yet been reported.Herein,we report two patients with diabetic foot ulcers treated with Nr-CWS.After wound debridement,the wound was covered with a sterile cotton ball infiltrated with an Nr-CWS that was diluted with 2.0 mL of saline.The covers were changed every two days until complete wound healing occurred.The two wounds healed after 3 and 12 weeks,respectively.This article aims to provide a new treatment for diabetic foot ulcers,with the hope that physicians may consider an Nr-CWS as a complementary method for the treatment of chronic wounds.展开更多
Oryza ridleyi is an allotetraploid wild species with the HHJJ genome, and Oryza sativa is a diploid cultivated rice that has the AA genome. Although the wide hybrid between the two species is difficult to obtain, we o...Oryza ridleyi is an allotetraploid wild species with the HHJJ genome, and Oryza sativa is a diploid cultivated rice that has the AA genome. Although the wide hybrid between the two species is difficult to obtain, we overcome this difficulty by young embryo rescue. An obvious heterosis was primarily found for the plant height, tillering ability, vegetative vigor, etc. However, the hybrid panicle and culm traits were found to resemble that of the wild rice parent, O. ridleyi, for the long awns, exoteric purple stigma, grain shattering, dispersed panicles, and culm mechanical strength. Genomic in situ hybridization (GISH) analysis was subsequently performed on the mitotic metaphase chromosome of the root tips, and we determined that the hybrid is an allotriploid with 36 chromosomes and its genomic constitution is AHJ. Chemical analyses conducted on the culm of O. sativa, O. ridleyi, and their interspecific hybrids showed that major changes occurred in the xylose, glucose, and arabinose concentrations, which are correlated with the specific hemicellulose polymer and cellulose components that are important in the primary cell walls of green plants. Meanwhile, the culm anatomical analyses indicated that additional large vascular bundles and an extra sclerenchyma cell layer were found in O. ridleyi. Additionally, further thickening of the secondary cell walls of the cortical fiber sclerenchyma cells and the phloem companion cells was discovered in O. ridleyi and in the interspecific hybrids. These results imply that there may be a potential link between culm mechanical strength and culm anatomical structure.展开更多
The effects of different Chinese traditional medicines were solvents on the extraction of effective studied by the histochemical methods, components from the cell wall tissues of such as the bare-handed section, swell...The effects of different Chinese traditional medicines were solvents on the extraction of effective studied by the histochemical methods, components from the cell wall tissues of such as the bare-handed section, swelling ratio, paraffin section, IR spectrum and cell wall component analysis. The results show that the ethanol-alkali solvent could increase the swelling ratio as well as the swelling speed. The effective components of cell wall tissues extracted by ethanol-alkali solvent become loose shown by the paraffin section. According to the IR spectrum analysis and the results of cell wall tissue component analysis, it was found that the ethanol-alkali solvent could decrease the contents of pectin and hemicellulose in the cell wall to make the wall broken, and therefore the effective components can be extracted easily by the solvent and the extraction rate is increased.展开更多
Plant cell walls constitute the skeletal structures of plant bodies,and thus confer lodging resistance for grain crops.While the basic cell wall synthesis machinery is relatively well established now,our understanding...Plant cell walls constitute the skeletal structures of plant bodies,and thus confer lodging resistance for grain crops.While the basic cell wall synthesis machinery is relatively well established now,our understanding of how the process is regulated remains limited and fragmented.In this study,we report the identification and characterization of the novel rice(Oryza sativa L.)brittle culm16(brittle node;bc16)mutant.The brittle node phenotype of the bc16 mutant appears exclusively at nodes,and resembles the previously reported bc5 mutant.Combined histochemical staining and electron microscopy assays revealed that in the bc16 mutant,the secondary cell wall formation and thickening of node sclerenchyma tissues are seriously affected after heading.Furthermore,cell wall composition assays revealed that the bc16 mutation led to a significant reduction in cellulose and lignin contents.Using a map-based cloning approach,the bc16 locus is mapped to an approximately 1.7-Mb region of chromosome 4.Together,our findings strengthen evidence for discretely spatial differences in the secondary cell wall formation within plant bodies.展开更多
Cell walls in plants,particularly forest trees,are the major carbon sink of the terrestrial ecosystem.Chemical and biosynthetic features of plant cell walls were revealed early on,focusing mostly on herbaceous model s...Cell walls in plants,particularly forest trees,are the major carbon sink of the terrestrial ecosystem.Chemical and biosynthetic features of plant cell walls were revealed early on,focusing mostly on herbaceous model species.Recent developments in genomics,transcriptomics,epigenomics,transgenesis,and associated analytical techniques are enabling novel insights into formation of woody cell walls.Here,we review multilevel regulation of cell wall biosynthesis in forest tree species.We highlight current approaches to engineering cell walls as potential feedstock for materials and energy and survey reported field tests of such engineered transgenic trees.We outline opportunities and challenges in future research to better understand cell type biogenesis for more efficient wood cell wall modification and utilization for biomaterials or for enhanced carbon capture and storage.展开更多
Pectin contributes greatly to cell wall phosphorus(P)remobilization.However,it is currently unclear whether the methylesterification degree of the pectin,which is related to the activity of pectin methylesterases(PMEs...Pectin contributes greatly to cell wall phosphorus(P)remobilization.However,it is currently unclear whether the methylesterification degree of the pectin,which is related to the activity of pectin methylesterases(PMEs),is also involved in this process.Here,we demonstrated that elevated PME activity can facilitate the remobilization of P deposited in the cell wall.P-deficient conditions resulted in the reduction of root cell wall P content.This reduction was more pronounced in Nipponbare than in Kasalath,in company with a significant increment of the PME activity,indicating a possible relationship between elevated PME activity and cell wall P remobilization.This hypothesis was supported by in vitro experiments,as pectin with lower methylesterification degree had higher ability to release inorganic P(Pi)from insoluble FePO_(4).Furthermore,among the 35 OsPME members in rice,only the expression of OsPME14 showed a relationship with PME activity.In addition,transgenic rice lines overexpressing OsPME14 had increased PME activity,released more P from the root cell wall,and more resistant to P deficiency.In conclusion,PMEs enhance P remobilization in P-starved rice by increasing PME activity in Nipponbare,which in turn helps to remobilize P from the cell wall,and thus makes more available P.展开更多
Characterizing the mechanical properties of wood cell walls will lead to better understanding and optimization of modifications made to wood infected by the blue-stain fungi.In this study,in situ nanoindentation was u...Characterizing the mechanical properties of wood cell walls will lead to better understanding and optimization of modifications made to wood infected by the blue-stain fungi.In this study,in situ nanoindentation was used to characterize the mechanical properties of the cell walls of Pinus massoniana infected by blue-stain fungi at the cellular level.The results show that in situ nanoindentation is an effective method for this purpose and that blue-stain fungi penetrate wood structures and degrade wood cell walls,significantly reducing the mechanical properties of the cell walls.The method can also be used to evaluate and improve the properties of other wood species infected by blue-stain fungi.展开更多
The cell walls of plants are mainly made of cellulose and contain a large number of calories.However,the main component,cellulose,is an indigestible plant fiber that is thought to be difficult for humans to use as ene...The cell walls of plants are mainly made of cellulose and contain a large number of calories.However,the main component,cellulose,is an indigestible plant fiber that is thought to be difficult for humans to use as energy.Herbivores acquire energy through the degradation of cell wall-derived dietary fiber by microorganisms in the digestive tract.Herbivores,especially horses,have a highly developed cecum and large intestine,and plants are fermented for their efficient use with the help of microorganisms.Humans also have an intestinal tract with a wide lumen on the proximal side of the large intestine,in which fermentation occurs.The digestive process of horses is similar to that of humans,and many of the intestinal bacteria found in horses that degrade plants are also found in humans.Therefore,it is thought that humans also obtain a certain amount of energy from cell wall-derived dietary fiber.However,the intake of dietary fiber by modern humans is low;thus,the amount of calories derived from indigestible plant fiber is considered to be very low.Cellulose in the plant cell wall is often accompanied by hemicellulose,pectin,lignin,suberin,and other materials.These materials are hard to degrade,and cellulose is therefore difficult for animals to utilize.If the cell wall can be degraded to some extent by cooking,it is thought that humans can obtain calories from cell wall-derived dietary fiber.If humans can use the calories from the cell wall for their diet,it may compensate for human food shortages.展开更多
Boron(B) is an essential micronutrient for vascular plant growth. Both B deficiency and toxicity can impair tissue development in diverse plant species, but little is known about the effect of B on reproductive panicl...Boron(B) is an essential micronutrient for vascular plant growth. Both B deficiency and toxicity can impair tissue development in diverse plant species, but little is known about the effect of B on reproductive panicle development and grain yield. In this study, a mutant of Setaria italica exhibiting necrotic panicle apices was identified and designated as sibor1. Sequencing revealed a candidate gene, Si BOR1, with a G-to-A alteration at the seventh exon. Knockout transgenic lines generated by clustered regularly interspaced short palindromic repeats and their associated protein-9 also had necrotic panicles, verifying the function of Si BOR1. Si BOR1 encoded a membrane-localized B efflux transporter, co-orthologous to the rice BOR1 protein. Si BOR1 was dominantly expressed in panicles and displayed a distinct expression pattern from those of its orthologs in other species. The induced mutation in Si BOR1 caused a reduction in the B content of panicle primary branches, and B deficiency-associated phenotypes such as thicker cell walls and higher cell porosity compared with Yugu 1. Transcriptome analysis indicated that differentially expressed genes involved in cell wall biogenesis, jasmonic acid synthesis, and programmed cell death response pathways were enriched in sibor1. q PCR analysis identified several key genes, including phenylalanine ammonia-lyase(Si PAL) and jasmonate-ZIM-domain(Si JAZ) genes, responsive to B-deficient conditions. These results indicate that Si BOR1 helps to regulate panicle primary branch development to maintain grain yield in S. italica. Our findings shed light on molecular mechanisms underlying the relationship between B transport and plant development in S. italica.展开更多
In this study,Pinus massoniana Lamb at different heights,across the annual rings,and between earlywood and latewood was measured by X-ray diffraction and the chemical composition was analyzed by chemical treatment.Res...In this study,Pinus massoniana Lamb at different heights,across the annual rings,and between earlywood and latewood was measured by X-ray diffraction and the chemical composition was analyzed by chemical treatment.Results indicated that the microfibril angle(MFA)decreased and the chemical composition changed little with the increase in height from 1 m to 9 m.In the radial direction,the MFA decreased and the chemical composition changed little with an increase in annual rings.The cellulose content of latewood was higher than that of early-wood.The viscoelastic changes of wood cell walls at different heights,across the annual rings by the method of quasi-static nanoindentation and dynamic modulus mapping techniques.Results indicated that the wood cell walls’elastic modulus increased,and the creep rate and creep compliance decreased with the increase in height;The elastic modulus and hardness increased with the annual rings.The cell walls’storage modulus increased and the loss modulus gradually decreased with an increase in height;the storage modulus gradually increased and the loss modulus decreased with the annual rings.展开更多
[ Objective ] This study aimed to confirm the roles of cell wall degrading enzymes (CWDEs) produced by Botryodiplodia theobromae Pat. in the infec- tion of mango fruits. [ Method] Change of activities of five types ...[ Objective ] This study aimed to confirm the roles of cell wall degrading enzymes (CWDEs) produced by Botryodiplodia theobromae Pat. in the infec- tion of mango fruits. [ Method] Change of activities of five types of CWDEs produced by B. theobromae Pat. were studied under both in vitro culture and inocula- tion conditions, along with the pathogenicity and the ability of producing CWDEs of four post-harvest fangal pathogens(B, theobromae Pat. , Colletotrichum gloeos- porioides Penz. , Phomopsis mangiferae Ahmad and Dothiorella dominicana Pet. et Cif. ) which cause stem-end rot of mangoes. [ Result] B. theobromae Pat. was a- ble to produce polygalacturonase(PG), pectinmethylgalacturonase(PMG), polygalacturonic acid trans-eliminase (PGTE), pectin methyltrans-eliminase (PMTE) and cellulase ( Cx. ) under both in vitro culture and inoculation conditions, of which activities of PG, Cx and PMG were significantly higher in than that in either PGTE or PMTE. Among three primary CWDEs, the peak of activities of PG and Cx appeared earlier and that of PMG occured later. The pathogenicity of B. theo- bromae Pat. was significantly higher than that of any other three pathogens; it is the same with the abilities of producing pectinase. [ Conclusion] This paper pro- vides theoretical bases for further exploring the mechanism of host-pathogen interaction and decreasing the post-harvest loss of mango fruits.展开更多
基金the National Natural Science Foundation of China(31701546)the Fundamental Research Funds for the Central Universities of China(2019ZD40)+5 种基金the 111 Project(B17018)for financial supportPearl River Talent Recruitment Program of Guangdong Province(2017GC010229)the Pearl River Nova Program of Guangzhou(201906010079)the National Natural Science Foundation of China(32001691)the special fund for scientific innovation strategyconstruction of high-level academy of agriculture science(R2019YJYB1001)the Application-oriented Projects of Guangdong Province(2017B020232002)。
文摘Natural foods,such as whole pulses,are recommended in the dietary guidelines of the US and China.The plant cell wall structure in whole pulses has important implications for the nutritional functionalities of starch.In this study,garbanzo bean cells with varying degrees of cell wall integrity were subjected to dry heat treatment(DHT)and used to elucidate the food structure-starch digestion properties of pulse food.The morphological features suggested that all cell samples do not exhibit remarkable changes after being subjected to DHT.Molecular rearrangement and the crystallite disruption of starch granules entrapped in cells occurred during DHT as assessed by the crystal structure and thermal properties.DHT decreased the inhibitory effects of enzymes of both the soluble and insoluble components,but the digestion rate and extent of slightly and highly damaged cell samples did not exhibit significant differences compared with their native counterparts.We concluded that the starch digestion of pulse cotyledon cells is primarily determined by the intactness of the cellular structure.This study reveals the role of food structure on the ability to retain the desirable nutritional properties of starch after subjection to physical modification.
基金supported by the Foundation for Distinguished Young Scholars of Jiangsu Province,China(Grant No.BK20190050)Zhejiang Provincial Natural Science Foundation of China(Grant No.LY22C130004)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2015250)。
文摘Phosphorus(P) starvation in rice facilitates the reutilization of root cell wall P by enhancing the pectin content. NaCl modulates pectin content, however, it is still unknown whether NaCl is also involved in the process of pectin regulated cell wall P remobilization in rice under P starved conditions. In this study, we found that 10 mmol/L NaCl increased the shoot and root biomasses under P deficiency to a remarkable extent, in company with the elevated shoot and root soluble P contents in rice. Further analysis indicated that exogenous NaCl enhanced the root cell wall P mobilization by increasing the pectin methylesterase activity and uronic acid content in pectin suggesting the involvement of NaCl in the process of cell wall P reutilization in P starved rice roots. Additionally, exogenous NaCl up-regulated the expression of P transporter OsPT6, which was induced by P deficiency, suggesting that NaCl also facilitated the P translocation prominently from root to shoot in P starved rice. Moreover, exogenous abscisic acid(ABA) can reverse the NaCl-mediated mitigation under P deficiency, indicating the involvement of ABA in the NaCl regulated root cell wall P reutilization. Taken together, our results demonstrated that NaCl can activate the reutilization of root cell wall P in P starved rice, which is dependent on the ABA accumulation pathway.
基金supported by the China Agriculture Research System of MOF and MARA (CARS-27)
文摘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.
基金supported by the Key Research and Development Program of Zhejiang Province(2021C02056,2021C02063-6)the National Key Research and Development Program of China(2021YFD1200503)+1 种基金the Fundamental Research Funds for Central Public Welfare Research Institutes of China National Rice Research Institute(CPSIBRF-CNRRI-202101)Chinese Academy of Agricultural Sciences(CAAS-ASTIP-201X-CNRRI)。
文摘Because plant mechanical strength influences plant growth and development,the regulatory mechanisms underlying cell-wall synthesis deserve investigation.Rice mutants are useful for such research.We have identified a novel brittle culm 25(bc25)mutant with reduced growth and partial sterility.BC25 encodes an UDP-glucuronic acid decarboxylase involved in cellulose synthesis and belongs to the UXS family.A single-nucleotide mutation in BC25 accounts for its altered cell morphology and cellwall composition.Transmission electron microscopy analysis showed that the thickness of the secondary cell wall was reduced in bc25.Monosaccharide analysis revealed significant increases in content of rhamnose and arabinose but not of other monosaccharides,indicating that BC25 was involved in xylose synthesis with some level of functional redundancy.Enzymatic assays suggested that BC25 functions with high activity to interconvert UDP-glucuronic acid(UDP-Glc A)and UDP-xylose.GUS staining showed that BC25 was ubiquitously expressed with higher expression in culm,root and sheath,in agreement with that shown by quantitative real-time(q RT)-PCR.RNA-seq further suggested that BC25 is involved in sugar metabolism.We conclude that BC25 strongly influences rice cell wall formation.
基金funded by the National Key Research and Development Program of China(2021YFF1000302)Fundamental Research Funds for the Central Universities of China(06500136)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-20-038).
文摘Plant cell elongation depends on well-defined gene regulations,adequate nutrients,and timely cell wall modifications.Anther size is positively correlated with the number and viability of pollen grains,while little is known about molecular mechanisms underlying anther cell elongation.Here,we found that properly activated cell elongation regulators at transcriptional levels in loss-of-function ZmMs33 mutant(ms33-6038)anthers failed to promote maize anther elongation.ZmMs33 deficiency disrupted metabolic homeostasis mainly by inhibiting both photosynthesis in anther endothecium and lipid accumulation in anther tapetum.Importantly,ms33-6038 anthers displayed ectopic,premature and excessive secondary cell wall thickening in anther middle layer,which constrained cell elongation structurally and blocked nutrient flows across different anther wall layers.The metabolic disorder was only found in ms33-6038 mutant rather than several representative male-sterility lines at transcriptional and post-translational levels.Collectively,the disordered metabolisms and blocked nutrient flows defeated the activated cell elongation regulators,and finally inhibited anther elongation and growth with a unique‘‘idling effect”in ms33-6038 mutant.
基金supported by the National Key Research and Development Program of China(2017YFD0101201 and2016YFD0101002)the Chinese Academy of Agricultural Sciences through the Agricultural Science and Technology Innovation Program(CAAS-ASTIP-2017-TRICAAS)National Engineering Laboratory for Crop Molecular Breeding
文摘The cell wall composition and structure of the maize stalk directly affects its digestibility and in turn its feed value.Previous studies of stem quality have focused mostly on common maize germplasm,and few studies have focused on high-oil cultivars with high grain and straw quality.Investigation of the genetic basis of cell wall composition and digestibility of maize stalk using high-oil maize is desirable for improving maize forage quality.In the present study,a high-oil inbred line(By804)was crossed as male parent with the maize inbred line B73 to construct a population of 188 recombinant inbred lines(RILs).The phenotypes of six cell-wall-related traits were recorded,and QTL analysis was performed with a genetic map constructed with SNP markers.All traits were significantly correlated with one another and showed high broad-sense heritability.Of 20 QTLs mapped,the QTL associated with each trait explained 10.0%–41.1%of phenotypic variation.Approximately half of the QTL each explained over 10%of the phenotypic variation.These results provide a theoretical basis for improving maize forage quality by marker-assisted selection.
基金the National Natural Science Foundation of China(31801367)the National Key Research and Development Program of China(2016YFD0101200)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences.
文摘Cell wall architecture plays a key role in stalk strength and forage digestibility.Lignin,cellulose,and hemicellulose are the three main components of plant cell walls,and they can impact stalk quality by affecting the structure and strength of the cell wall.To explore cell wall development during secondary cell wall lignification in maize stalks,conventional and conditional genetic mapping were used to identify the dynamic quantitative trait loci(QTLs)of the cell wall components and digestibility traits during five growth stages after silking.Acid detergent lignin(ADL),cellulose(CEL),acid detergent fiber(ADF),neutral detergent fiber(NDF),and in vitro dry matter digestibility(IVDMD)were evaluated in a maize recombinant inbred line(RIL)population.ADL,CEL,ADF,and NDF gradually increased from 10 to 40 days after silking(DAS),and then they decreased.IVDMD initially decreased until 40 DAS,and then it increased slightly.Seventytwo QTLs were identified for the five traits,and each accounted for 3.48–24.04%of the phenotypic variation.Six QTL hotspots were found,and they were localized in the 1.08,2.04,2.07,7.03,8.05,and 9.03 bins of the maize genome.Within the interval of the pleiotropic QTL identified in bin 1.08 of the maize genome,six genes associated with cell wall component biosynthesis were identified as potential candidate genes for stalk strength as well as cell wall-related traits.In addition,26 conditional QTLs were detected in the five stages for all of the investigated traits.Twenty-two of the 26 conditional QTLs were found at 30 DAS conditioned using the values of 20 DAS,and at 50 DAS conditioned using the values of 40 DAS.These results indicated that cell wall-related traits are regulated by many genes,which are specifically expressed at different stages after silking.Simultaneous improvements in both forage digestibility and lodging resistance could be achieved by pyramiding multiple beneficial QTL alleles identified in this study.
文摘The plant cell wall is a complex 3D network composed of polysaccharides, lignin and proteins. The knowledge of the structure and content of each cell wall polymer is a prerequisite to understand their functions during plant development and adaptation but also to optimise their industrial applications. The analysis of cell wall compounds is complicated by their multiple molecular interactions. In this review, we present numerous methods to purify, characterise and quantify proteins, polysaccharides and lignin from the wall. Two kinds of approaches are detailed: the first presents in vitro methods which involve the breakdown of the molecular linkages between polymers thanking to chemical, physical and/or enzymatic treatments. The second approach describes in situ methods that allow the cell wall polymer characterisation thanking to many analytical techniques coupled with microscopy. If microscopy is the common point of all of them, their development is associated with improvement of analytical techniques, increasing their power of resolution.
文摘The addition of p-coumaric acid (pCA) to lignin molecules is frequently found in members of the grass family. The role of this addition is not clearly understood, but is thought to potentially aid in the formation of syringyl-type lignin. This is because the incorporation is as a conjugate of pCA ester linked to sinapyl alcohol, a major component of lignin. The forage legume alfalfa (Medicago sativa L.) does not contain appreciable levels of pCA in its more heavily lignified stem tissues. The maize p-coumaryltransferase (pCAT) gene was used to transform alfalfa to determine its impact upon lignin composition and its potential to alter cell wall digestibility. A constitutive expression vector using the cassava vein mosaic virus (CsVMV) promoter was used to drive expression of maize pCAT in alfalfa. Expression of the pCAT transgene was detected in both leaves and stems. Though there was a range of pCAconcentration in transformed alfalfa stems (0.2 - 1.79 micrograms (μg)), this was a clear increase over bound pCA in control stems (0.15 - 0.2 mean = 0.17 micrograms (μg)). This did not lead to consistent responses concerning total lignin in the stem tissues. Leaf tissue, on the other hand, already has a relatively high level of pCA (0.85 - 1.2, mean = 0.99 micrograms (μg)) and those expressing pCAT gene showed on average a small increase, but there is a wide range of values among the transformants (0.38 - 1.55, mean = 1.06 micrograms (μg)). Lignin in leaves did not appear to be significantly impacted. However, incorporation of pCA into the wall appears to cause a shift in lignin composition. Testing the pCAT expressing stem cell walls for digestibility using a rumen in vitro system showed there was no change in the digestibility of the stem compared to empty vectors and control alfalfa stems. Although expression of pCAT gene in alfalfa changes the amount of wall bound pCA, it does not appear to change lignin levels or impact digestibility.
基金This study was sponsored by the National Natural Science Foundation of China(grant no.82172224).
文摘Diabetic foot ulcers are one of the most severe complications of diabetes that have imposed great financial and psychological burdens on diabetic patients.A Nocardia rubra cell wall skeleton(Nr-CWS)can be externally applied to accelerate wound healing.However,its clinical application has not yet been reported.Herein,we report two patients with diabetic foot ulcers treated with Nr-CWS.After wound debridement,the wound was covered with a sterile cotton ball infiltrated with an Nr-CWS that was diluted with 2.0 mL of saline.The covers were changed every two days until complete wound healing occurred.The two wounds healed after 3 and 12 weeks,respectively.This article aims to provide a new treatment for diabetic foot ulcers,with the hope that physicians may consider an Nr-CWS as a complementary method for the treatment of chronic wounds.
基金supported by the National Natural Science Foundation of China(31571624 and 31071382)the National Key Research and Development Program of China(2016YFD0102001-006)+2 种基金the National Basic Research(973)Program of China(2010CB125904-3,2013CBA01405)the Key Natural Science Project in University of Jiangsu Province,China(15KJA210004)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)
文摘Oryza ridleyi is an allotetraploid wild species with the HHJJ genome, and Oryza sativa is a diploid cultivated rice that has the AA genome. Although the wide hybrid between the two species is difficult to obtain, we overcome this difficulty by young embryo rescue. An obvious heterosis was primarily found for the plant height, tillering ability, vegetative vigor, etc. However, the hybrid panicle and culm traits were found to resemble that of the wild rice parent, O. ridleyi, for the long awns, exoteric purple stigma, grain shattering, dispersed panicles, and culm mechanical strength. Genomic in situ hybridization (GISH) analysis was subsequently performed on the mitotic metaphase chromosome of the root tips, and we determined that the hybrid is an allotriploid with 36 chromosomes and its genomic constitution is AHJ. Chemical analyses conducted on the culm of O. sativa, O. ridleyi, and their interspecific hybrids showed that major changes occurred in the xylose, glucose, and arabinose concentrations, which are correlated with the specific hemicellulose polymer and cellulose components that are important in the primary cell walls of green plants. Meanwhile, the culm anatomical analyses indicated that additional large vascular bundles and an extra sclerenchyma cell layer were found in O. ridleyi. Additionally, further thickening of the secondary cell walls of the cortical fiber sclerenchyma cells and the phloem companion cells was discovered in O. ridleyi and in the interspecific hybrids. These results imply that there may be a potential link between culm mechanical strength and culm anatomical structure.
基金Supported by the Major Program of Chinese Herbal Modernism Science of Jilin Provincial Science and Technology Department,China(No.20030906-01)
文摘The effects of different Chinese traditional medicines were solvents on the extraction of effective studied by the histochemical methods, components from the cell wall tissues of such as the bare-handed section, swelling ratio, paraffin section, IR spectrum and cell wall component analysis. The results show that the ethanol-alkali solvent could increase the swelling ratio as well as the swelling speed. The effective components of cell wall tissues extracted by ethanol-alkali solvent become loose shown by the paraffin section. According to the IR spectrum analysis and the results of cell wall tissue component analysis, it was found that the ethanol-alkali solvent could decrease the contents of pectin and hemicellulose in the cell wall to make the wall broken, and therefore the effective components can be extracted easily by the solvent and the extraction rate is increased.
基金supported by the Fundamental Research Funds for Excellent Young Scientists of Institute of Crop Sciences, Chinese Academy of Agricultural Sciences (Grant to YR, 2014JB04-009, 1610092015003-08)the National Transgenic Science and Technology Program, China (2016ZX08009003-003)
文摘Plant cell walls constitute the skeletal structures of plant bodies,and thus confer lodging resistance for grain crops.While the basic cell wall synthesis machinery is relatively well established now,our understanding of how the process is regulated remains limited and fragmented.In this study,we report the identification and characterization of the novel rice(Oryza sativa L.)brittle culm16(brittle node;bc16)mutant.The brittle node phenotype of the bc16 mutant appears exclusively at nodes,and resembles the previously reported bc5 mutant.Combined histochemical staining and electron microscopy assays revealed that in the bc16 mutant,the secondary cell wall formation and thickening of node sclerenchyma tissues are seriously affected after heading.Furthermore,cell wall composition assays revealed that the bc16 mutation led to a significant reduction in cellulose and lignin contents.Using a map-based cloning approach,the bc16 locus is mapped to an approximately 1.7-Mb region of chromosome 4.Together,our findings strengthen evidence for discretely spatial differences in the secondary cell wall formation within plant bodies.
基金supported by the National Key Research and Development Program of China(2021YFD2200700)the Fundamental Research Funds for the Central Universities of China(grant 2572022DQ01)+6 种基金the Heilongjiang Touyan Innovation Team Program(Tree Genetics and Breeding Innovation Team)the 111 Project(B16010)supported by the Young Scholar Fellowship Columbus Program from the Ministry of Science and Technology of Taiwan,China(111-2311-B-002-021)the National Science and Technology Council(112-2636-B-006-006)MEXT KAKENHI(JP18H05484,JP18H05489)the Research Foundation Flanders for proving the predoctoral fellowship.D.M.O.is indebted to the Research Foundation Flanders(FWO,grant 1246123N)for a postdoctoral fellowshipsupported by the Energy Transition Fund projects AdLibio and AdvBio,the interuniversity iBOF project NextBioRef,and the FWO project G011620N。
文摘Cell walls in plants,particularly forest trees,are the major carbon sink of the terrestrial ecosystem.Chemical and biosynthetic features of plant cell walls were revealed early on,focusing mostly on herbaceous model species.Recent developments in genomics,transcriptomics,epigenomics,transgenesis,and associated analytical techniques are enabling novel insights into formation of woody cell walls.Here,we review multilevel regulation of cell wall biosynthesis in forest tree species.We highlight current approaches to engineering cell walls as potential feedstock for materials and energy and survey reported field tests of such engineered transgenic trees.We outline opportunities and challenges in future research to better understand cell type biogenesis for more efficient wood cell wall modification and utilization for biomaterials or for enhanced carbon capture and storage.
基金This study was supported by the Foundation for Distinguished Young Scholars of Jiangsu Province,China(Grant No.BK20190050)Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2015250)+2 种基金the‘Strategic Priority Research Program’of the Chinese Academy of Sciences(Grant No.XDB15030300)National Science Foundation of China(Grant No.31501825)the State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources in China in 2020(Grant No.SKLCUSA-b201909).
文摘Pectin contributes greatly to cell wall phosphorus(P)remobilization.However,it is currently unclear whether the methylesterification degree of the pectin,which is related to the activity of pectin methylesterases(PMEs),is also involved in this process.Here,we demonstrated that elevated PME activity can facilitate the remobilization of P deposited in the cell wall.P-deficient conditions resulted in the reduction of root cell wall P content.This reduction was more pronounced in Nipponbare than in Kasalath,in company with a significant increment of the PME activity,indicating a possible relationship between elevated PME activity and cell wall P remobilization.This hypothesis was supported by in vitro experiments,as pectin with lower methylesterification degree had higher ability to release inorganic P(Pi)from insoluble FePO_(4).Furthermore,among the 35 OsPME members in rice,only the expression of OsPME14 showed a relationship with PME activity.In addition,transgenic rice lines overexpressing OsPME14 had increased PME activity,released more P from the root cell wall,and more resistant to P deficiency.In conclusion,PMEs enhance P remobilization in P-starved rice by increasing PME activity in Nipponbare,which in turn helps to remobilize P from the cell wall,and thus makes more available P.
文摘Characterizing the mechanical properties of wood cell walls will lead to better understanding and optimization of modifications made to wood infected by the blue-stain fungi.In this study,in situ nanoindentation was used to characterize the mechanical properties of the cell walls of Pinus massoniana infected by blue-stain fungi at the cellular level.The results show that in situ nanoindentation is an effective method for this purpose and that blue-stain fungi penetrate wood structures and degrade wood cell walls,significantly reducing the mechanical properties of the cell walls.The method can also be used to evaluate and improve the properties of other wood species infected by blue-stain fungi.
文摘The cell walls of plants are mainly made of cellulose and contain a large number of calories.However,the main component,cellulose,is an indigestible plant fiber that is thought to be difficult for humans to use as energy.Herbivores acquire energy through the degradation of cell wall-derived dietary fiber by microorganisms in the digestive tract.Herbivores,especially horses,have a highly developed cecum and large intestine,and plants are fermented for their efficient use with the help of microorganisms.Humans also have an intestinal tract with a wide lumen on the proximal side of the large intestine,in which fermentation occurs.The digestive process of horses is similar to that of humans,and many of the intestinal bacteria found in horses that degrade plants are also found in humans.Therefore,it is thought that humans also obtain a certain amount of energy from cell wall-derived dietary fiber.However,the intake of dietary fiber by modern humans is low;thus,the amount of calories derived from indigestible plant fiber is considered to be very low.Cellulose in the plant cell wall is often accompanied by hemicellulose,pectin,lignin,suberin,and other materials.These materials are hard to degrade,and cellulose is therefore difficult for animals to utilize.If the cell wall can be degraded to some extent by cooking,it is thought that humans can obtain calories from cell wall-derived dietary fiber.If humans can use the calories from the cell wall for their diet,it may compensate for human food shortages.
基金supported by the National Key Research and Development Program of China(2019YFD1000700 and 2019YFD1000704)the National Natural Science Foundation of China(31871692)+1 种基金the China Agricultural Research System(CARS06-13.5-A04)the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences。
文摘Boron(B) is an essential micronutrient for vascular plant growth. Both B deficiency and toxicity can impair tissue development in diverse plant species, but little is known about the effect of B on reproductive panicle development and grain yield. In this study, a mutant of Setaria italica exhibiting necrotic panicle apices was identified and designated as sibor1. Sequencing revealed a candidate gene, Si BOR1, with a G-to-A alteration at the seventh exon. Knockout transgenic lines generated by clustered regularly interspaced short palindromic repeats and their associated protein-9 also had necrotic panicles, verifying the function of Si BOR1. Si BOR1 encoded a membrane-localized B efflux transporter, co-orthologous to the rice BOR1 protein. Si BOR1 was dominantly expressed in panicles and displayed a distinct expression pattern from those of its orthologs in other species. The induced mutation in Si BOR1 caused a reduction in the B content of panicle primary branches, and B deficiency-associated phenotypes such as thicker cell walls and higher cell porosity compared with Yugu 1. Transcriptome analysis indicated that differentially expressed genes involved in cell wall biogenesis, jasmonic acid synthesis, and programmed cell death response pathways were enriched in sibor1. q PCR analysis identified several key genes, including phenylalanine ammonia-lyase(Si PAL) and jasmonate-ZIM-domain(Si JAZ) genes, responsive to B-deficient conditions. These results indicate that Si BOR1 helps to regulate panicle primary branch development to maintain grain yield in S. italica. Our findings shed light on molecular mechanisms underlying the relationship between B transport and plant development in S. italica.
基金The authors would like to gratefully acknowledge Natural Science Foundation of China(31570552).
文摘In this study,Pinus massoniana Lamb at different heights,across the annual rings,and between earlywood and latewood was measured by X-ray diffraction and the chemical composition was analyzed by chemical treatment.Results indicated that the microfibril angle(MFA)decreased and the chemical composition changed little with the increase in height from 1 m to 9 m.In the radial direction,the MFA decreased and the chemical composition changed little with an increase in annual rings.The cellulose content of latewood was higher than that of early-wood.The viscoelastic changes of wood cell walls at different heights,across the annual rings by the method of quasi-static nanoindentation and dynamic modulus mapping techniques.Results indicated that the wood cell walls’elastic modulus increased,and the creep rate and creep compliance decreased with the increase in height;The elastic modulus and hardness increased with the annual rings.The cell walls’storage modulus increased and the loss modulus gradually decreased with an increase in height;the storage modulus gradually increased and the loss modulus decreased with the annual rings.
基金Supported by the Special Fund for Agro-scientific Research(3-44-2)the Special Fund for Basic Research of Central Universities in the Public Interest,China(N0.2009hzs1J011,NO.2011hzs1J027,NO.2011hzs1J004)
文摘[ Objective ] This study aimed to confirm the roles of cell wall degrading enzymes (CWDEs) produced by Botryodiplodia theobromae Pat. in the infec- tion of mango fruits. [ Method] Change of activities of five types of CWDEs produced by B. theobromae Pat. were studied under both in vitro culture and inocula- tion conditions, along with the pathogenicity and the ability of producing CWDEs of four post-harvest fangal pathogens(B, theobromae Pat. , Colletotrichum gloeos- porioides Penz. , Phomopsis mangiferae Ahmad and Dothiorella dominicana Pet. et Cif. ) which cause stem-end rot of mangoes. [ Result] B. theobromae Pat. was a- ble to produce polygalacturonase(PG), pectinmethylgalacturonase(PMG), polygalacturonic acid trans-eliminase (PGTE), pectin methyltrans-eliminase (PMTE) and cellulase ( Cx. ) under both in vitro culture and inoculation conditions, of which activities of PG, Cx and PMG were significantly higher in than that in either PGTE or PMTE. Among three primary CWDEs, the peak of activities of PG and Cx appeared earlier and that of PMG occured later. The pathogenicity of B. theo- bromae Pat. was significantly higher than that of any other three pathogens; it is the same with the abilities of producing pectinase. [ Conclusion] This paper pro- vides theoretical bases for further exploring the mechanism of host-pathogen interaction and decreasing the post-harvest loss of mango fruits.