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Adjacent plant cells are connected by specialized cell wall regions, called middle lamellae, which influence critical agricultural characteristics, including fruit ripening and organ abscission. Middle lamellae are enriched in pectin polysaccharides, specifically homogalacturonan (HG). Here, we identify a plant-specific Arabidopsis DUF1068 protein, called NKS1/ELMO4, that is required for middle lamellae integrity and cell adhesion. NKS1 localizes to the Golgi apparatus and loss of NKS1 results in changes to Golgi structure and function. The nks1 mutants also display HG deficient phenotypes, including reduced seedling growth, changes to cell wall composition, and tissue integrity defects. These phenotypes are comparable to qua1 and qua2 mutants, which are defective in HG biosynthesis. Notably, genetic interactions indicate that NKS1 and the QUAs work in a common pathway. Protein interaction analyses and modeling corroborate that they work together in a stable protein complex with other pectin-related proteins. We propose that NKS1 is an integral part of a large pectin synthesis protein complex and that proper function of this complex is important to support Golgi structure and function.

Green biomass from leguminous and gramineous forage crops, such as alfalfa and grass-clover, has been proposed as a potential new source of feed protein concentrates for non-ruminant livestock. However, the efficient separation of the protein fraction from the non-digestible cell components, primarily comprising cell walls (fiber) and starch, presents a significant technological challenge. Moreover, it is crucial to optimize the process to preserve the optimal nutritional value of the final product. This study comprehensively analyzed the non-digestible fiber content and composition across all biorefinery fractions using two different feedstocks: green biomass from alfalfa and grass-clover. The pilot scale refining process involved a combination of screw pressing, lactic acid fermentation, and protein separation via centrifugation. We observed variations in carbohydrate composition and abundance between alfalfa and grass-clover. The lactic acid fermentation led to a reduction in cellulose and total glucose content. Our findings indicate that the final protein concentrate still contains residual cell wall components, including lignin, indicating potential inefficiencies in the filtration, fermentation, and isolation steps. The presented analytical approach provides a valuable framework for optimizing processing conditions and tailoring enzyme cocktails for enhanced valorization of the by-products.

Adjacent plant cells are connected by specialized cell wall regions, called middle lamellae, which influence critical agricultural characteristics, including fruit ripening and organ abscission. Middle lamellae are enriched in pectin polysaccharides, specifically homogalacturonan (HG). Here, we identify a plant-specific Arabidopsis DUF1068 protein, called NKS1/ELMO4, that is required for middle lamellae integrity and cell adhesion. NKS1 localizes to the Golgi apparatus and loss of NKS1 results in changes to Golgi structure and function. The nks1 mutants also display HG deficient phenotypes, including reduced seedling growth, changes to cell wall composition, and tissue integrity defects. These phenotypes are comparable to qua1 and qua2 mutants, which are defective in HG biosynthesis. Notably, genetic interactions indicate that NKS1 and the QUAs work in a common pathway. Protein interaction analyses and modeling corroborate that they work together in a stable protein complex with other pectin-related proteins. We propose that NKS1 is an integral part of a large pectin synthesis protein complex and that proper function of this complex is important to support Golgi structure and function.

Woody cells, such as tracheids, fibers, vessels, rays etc., have unique structural characteristics such as nano-scale ultrastructure represented by multilayers, microfibril angle (MFA), micro-scale anatomical properties and spatial arrangement. Simultaneous evaluation of the above indices is very important for their adequate quantification and extracting the effects of external stimuli from them. However, it is difficult in general to achieve the above only by traditional methodologies. To overcome the above point, a new methodological framework combining polarization optical microscopy, fluorescence microscopy, and image segmentation is proposed. The framework was tested to a model softwood species, Chamaecyparis obtusa for characterizing intra-annual transition of MFA and tracheid morphology in a radial file unit. According our result, this framework successfully traced the both characteristics tracheid by tracheid and revealed the high correlation (|r| > 0.5) between S2 microfibril angles and tracheidal morphology (lumen radial diameter, tangential wall thickness and cell wall occupancy). In addition, radial file based evaluation firstly revealed their complex transitional behavior in transition and latewood. The proposed framework has great potential as one of the unique tools to provide detailed insights into heterogeneity of intra and inter-cells in the wide field of view through the simultaneous evaluation of cells’ ultrastructure and morphological properties.

The structural arrangement of the polymers in the cell wall of wood has still not been fully established. This relates specifically to the role of the two hemicelluloses, glucomannan and xylan, in the secondary cell wall. In softwoods there is a good consensus with regard to the glucomannan as associated with the cellulose microfibrils while the role of the xylan has been more questioned. Recent NMR-studies have now strongly indicated a close association of xylan also to the cellulose microfibrils in softwoods. In order to assess these findings, studies utilizing complementary techniques are here re-examined in order to scrutinize these results. By analyzing results from polymer orientation (polarized FTIR), molecular blending (dynamic mechanical analysis), polymer interaction (dynamic FTIR) and moisture induced swelling (synchrotron X-ray) a close association of xylan to cellulose is here fully supported. Thus, the overall results from all multiple techniques strongly advocate an association of both glucomannan and xylan to the cellulose microfibrils and aggregates while the lignin is considered as encompassing the remaining space between the undulating cellulose/hemicellulose aggregate structures and acting as an independent polymer entity. Graphical abstract: [Figure not available: see fulltext.]., QC 20221006

The effects of five different types of imperfection (fractured cell walls, missing cells, cell wall waviness, cell wall misalignment, and non-uniform cell wall thickness) on actuation performance are numerically investigated for the Kagome lattice and two of its variants: Double Kagome (DK) and Kagome with concentric triangles (KT). The lattice materials of interest are excited by deploying a single linear actuator located at their centre. The actuation performance of the lattices is determined by measuring the energy spent by the actuator and the attenuation distance of the deformation induced by the actuator. The deformation localises in a narrow corridor approximately one unit cell-wide for all three lattices in the absence of imperfections. The finite element calculations show that the critical parameter determining the actuation performance is the stiffness along the actuation corridor rather than the macroscopic Young's modulus of the lattice. The less stiff the actuation corridor is, the smaller the actuation energy and the larger the attenuation distance (except when there is a fractured or wavy cell wall or a missing cell along the actuation corridor that immediately attenuates the displacement field). When imperfections are randomly distributed outside the actuation corridor, cell wall misalignment and non-uniform cell wall thickness barely affect the actuation performance, although cell wall misalignment considerably reduces the macroscopic Young's modulus of the lattice. The actuator feels the presence of fractured or wavy cell walls or missing cells, whether placed inside or outside the actuation corridor. These three types of imperfection cause the largest knock-down both in the macroscopic Young's modulus of the block and the actuation energy while increasing the attenuation distance. The increase in the attenuation distance due to imperfections is, however, impotent, as the accompanying reduction in stiffness makes the lattice more vulnerable to fail, Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK: 219M296, The authors gratefully acknowledge the financial support by TÜBİTAK (The Scientific and Technological Research Council of Turkey, Project Title: Design of New Multi-Functional Lattice Materials; Project No: 219M296 ).

The effects of five different types of imperfection (fractured cell walls, missing cells, cell wall waviness, cell wall misalignment, and non-uniform cell wall thickness) on actuation performance are numerically investigated for the Kagome lattice and two of its variants: Double Kagome (DK) and Kagome with concentric triangles (KT). The lattice materials of interest are excited by deploying a single linear actuator located at their centre. The actuation performance of the lattices is determined by measuring the energy spent by the actuator and the attenuation distance of the deformation induced by the actuator. The deformation localises in a narrow corridor approximately one unit cell-wide for all three lattices in the absence of imperfections. The finite element calculations show that the critical parameter determining the actuation performance is the stiffness along the actuation corridor rather than the macroscopic Young's modulus of the lattice. The less stiff the actuation corridor is, the smaller the actuation energy and the larger the attenuation distance (except when there is a fractured or wavy cell wall or a missing cell along the actuation corridor that immediately attenuates the displacement field). When imperfections are randomly distributed outside the actuation corridor, cell wall misalignment and non-uniform cell wall thickness barely affect the actuation performance, although cell wall misalignment considerably reduces the macroscopic Young's modulus of the lattice. The actuator feels the presence of fractured or wavy cell walls or missing cells, whether placed inside or outside the actuation corridor. These three types of imperfection cause the largest knock-down both in the macroscopic Young's modulus of the block and the actuation energy while increasing the attenuation distance. The increase in the attenuation distance due to imperfections is, however, impotent, as the accompanying reduction in stiffness makes the lattice more vulnerable to fail, Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK: 219M296, The authors gratefully acknowledge the financial support by TÜBİTAK (The Scientific and Technological Research Council of Turkey, Project Title: Design of New Multi-Functional Lattice Materials; Project No: 219M296 ).

Succulence is an adaptation to low water availability characterised by the presence of water-storage tissues that alleviate water stress under low water availability. The succulent syndrome has evolved convergently in over 80 plant families and is associated with anatomical, physiological and biochemical traits. Despite the alleged importance of cell wall traits in drought responses, their significance in the succulent syndrome has long been overlooked. Here, by analyzing published pressure–volume curves, we show that elastic adjustment, whereby plants change cell wall elasticity, is uniquely beneficial to succulents for avoiding turgor loss. In addition, we used comprehensive microarray polymer profiling (CoMPP) to assess the biochemical composition of cell walls in leaves. Across phylogenetically diverse species, we uncover several differences in cell wall biochemistry between succulent and non-succulent leaves, pointing to the existence of a ‘succulent glycome’. We also highlight the glycomic diversity among succulent plants, with some glycomic features being restricted to certain succulent lineages. In conclusion, we suggest that cell wall biomechanics and biochemistry should be considered among the characteristic traits that make up the succulent syndrome.

Succulence is an adaptation to low water availability characterised by the presence of water-storage tissues that alleviate water stress under low water availability. The succulent syndrome has evolved convergently in over 80 plant families and is associated with anatomical, physiological and biochemical traits. Despite the alleged importance of cell wall traits in drought responses, their significance in the succulent syndrome has long been overlooked. Here, by analyzing published pressure–volume curves, we show that elastic adjustment, whereby plants change cell wall elasticity, is uniquely beneficial to succulents for avoiding turgor loss. In addition, we used comprehensive microarray polymer profiling (CoMPP) to assess the biochemical composition of cell walls in leaves. Across phylogenetically diverse species, we uncover several differences in cell wall biochemistry between succulent and non-succulent leaves, pointing to the existence of a ‘succulent glycome’. We also highlight the glycomic diversity among succulent plants, with some glycomic features being restricted to certain succulent lineages. In conclusion, we suggest that cell wall biomechanics and biochemistry should be considered among the characteristic traits that make up the succulent syndrome.

Lactococcus lactis and Lactococcus cremoris are widely used as starters in the food industry but its activity may be compromised by bacteriophages, viruses that exclusively infect bacteria. Thus, a huge effort has been put to develop lactococcal phage-resistant strains. This dataset describes the results of experiments designed to test the hypothesis if a thwarted endolysin activity influences the outcome of phage infection. To this end, turbidity reduction assays were performed with Lys1358 and LysC2, endolysins with CHAP and lysozyme catalytic domains, respectively. Lactococcus mutants either overexpressing or lacking genes involved in the cell envelope stress (CES) response or in modifying peptidoglycan (PG) composition were used as substrate cells. Reduced activity on cells with an induced CES response was detected for both endolysins, while LysC2 showed increased activity against cells depleted of the PG deacetylase PgdA and the O-acetyl transferase OatA. By measuring several growth parameters of phage c2 on these mutants (lytic score, efficiency of plaquing, plaque size and one-step curves), we could not stablish a direct link between a reduced or enhanced exolytic activity of endolysin and phage performance.

The acetylation process involves chemical reaction between acetic anhydride and wood, which results in esterification of accessible hydroxyl groups in the cell wall, with formation of the by-product acetic acid. Acetylation of wood has been widely studied during the past decades, and several experimental studies have proven it to be effective in reducing the hygroscopicity of wood resulting in improved dimensional stability and fungal resistance. For load-bearing timber structures used in outdoor environment, the combination of acetylation and engineered wood products gives the possibility to manufacture more durable timber elements with remarkable dimensional stability without negatively affecting the mechanical properties. The objective of this study concerns the mechanical properties of both acetylated and untreated birch plywood loaded parallel to the face grain direction. The test results are compared and discussed., QC 20220603

Phenolic composition of young red wines has been shown to play an important role in their ageing potential. Therefore, the modulation of phenolic extraction during maceration may influence the subsequent phenolic evolution of these wines. The present work aimed to evaluate the impact of three different maceration times on the phenolic levels and evolution observed over time, using spectrophotometric and chromatography methods, and the effect on the aroma, taste, and mouthfeel sensory properties using Projective Mapping. Additionally, grape cell wall deconstruction was monitored during the extended maceration phase by GC-MS and Comprehensive Comprehensive Microarray Polymer Profiling (CoMPP). Our findings demonstrated that longer maceration times did not always correspond to an increase in wine phenolic concentration, although the level of complexity of these molecules seemed to be higher. Additionally, continuous depectination and possible solubilisation of the pectin is observed during the extended maceration which may be influencing the sensory perception of these wines. Maceration time was also shown to influence the evolution of the polymeric fraction and sensory perception of the wines.

Molecular-scale interactions between water and cellulose microfibril bundles in plant cell walls are not fully understood, despite their crucial role for many applications of plant biomass. Recent advances in X-ray and neutron scattering analysis allow more accurate interpretation of experimental data from wood cell walls. At the same time, microfibril bundles including hemicelluloses and water can be modelled at atomistic resolution. Computing scattering patterns from atomistic models enables a new, complementary approach to decipher some of the most fundamental questions at this level of the hierarchical cell wall structure. This article introduces studies related to moisture behavior of wood with small/wide-angle X-ray/neutron scattering and atomistic simulations, recent attempts to combine these two approaches, and perspectives and open questions for future research using this powerful combination. Finally, we discuss the opportunities of the combined method in relation to applications of lignocellulosic materials. © 2020 The Author(s)

The paper reviews a career of more than forty years researching topics in malting and brewing science. Some themes attracted particularly close attention, namely the endosperm cell walls of barley, dimethyl sulphide, flavour stability, foam and the impact of beer on health. However, the scope has been far broader than that. The underlying imperative was to pursue research that was close to application and always focussed on a specific need in the processes involved in the production of beer. © 2020 The Institute of Brewing & Distilling.

Large-scale, sustainable production of lignocellulosic bioenergy from biomass will depend on a variety of dedicated bioenergy crops. Despite their great genetic diversity, prospective bioenergy crops share many similarities in the polysaccharide composition of their cell walls, and the changes needed to optimize them for conversion are largely universal. Therefore, biomass modification strategies that do not depend on genetic background or require mutant varieties are extremely valuable. Due to their preferential fermentation and conversion by microorganisms downstream, the ideal bioenergy crop should contain a high proportion of C6-sugars in polysaccharides like cellulose, callose, galactan, and mixed-linkage glucans. In addition, the biomass should be reduced in inhibitors of fermentation like pentoses and acetate. Finally, the overall complexity of the plant cell wall should be modified to reduce its recalcitrance to enzymatic deconstruction in ways that do no compromise plant health or come at a yield penalty. This review will focus on progress in the use of a variety of genetically dominant strategies to reach these ideals. Due to the breadth and volume of research in the field of lignin bioengineering, this review will instead focus on approaches to improve polysaccharide component plant biomass. Carbohydrate content can be dramatically increased by transgenic overexpression of enzymes involved in cell wall polysaccharide biosynthesis. Additionally, the recalcitrance of the cell wall can be reduced via the overexpression of native or non-native carbohydrate active enzymes like glycosyl hydrolases or carbohydrate esterases. Some research in this area has focused on engineering plants that accumulate cell wall-degrading enzymes that are sequestered to organelles or only active at very high temperatures. The rationale being that, in order to avoid potential negative effects of cell wall modification during plant growth, the enzymes could be activated post-harvest

The paper reviews a career of more than forty years researching topics in malting and brewing science. Some themes attracted particularly close attention, namely the endosperm cell walls of barley, dimethyl sulphide, flavour stability, foam and the impact of beer on health. However, the scope has been far broader than that. The underlying imperative was to pursue research that was close to application and always focussed on a specific need in the processes involved in the production of beer. © 2020 The Institute of Brewing & Distilling.

Large-scale, sustainable production of lignocellulosic bioenergy from biomass will depend on a variety of dedicated bioenergy crops. Despite their great genetic diversity, prospective bioenergy crops share many similarities in the polysaccharide composition of their cell walls, and the changes needed to optimize them for conversion are largely universal. Therefore, biomass modification strategies that do not depend on genetic background or require mutant varieties are extremely valuable. Due to their preferential fermentation and conversion by microorganisms downstream, the ideal bioenergy crop should contain a high proportion of C6-sugars in polysaccharides like cellulose, callose, galactan, and mixed-linkage glucans. In addition, the biomass should be reduced in inhibitors of fermentation like pentoses and acetate. Finally, the overall complexity of the plant cell wall should be modified to reduce its recalcitrance to enzymatic deconstruction in ways that do no compromise plant health or come at a yield penalty. This review will focus on progress in the use of a variety of genetically dominant strategies to reach these ideals. Due to the breadth and volume of research in the field of lignin bioengineering, this review will instead focus on approaches to improve polysaccharide component plant biomass. Carbohydrate content can be dramatically increased by transgenic overexpression of enzymes involved in cell wall polysaccharide biosynthesis. Additionally, the recalcitrance of the cell wall can be reduced via the overexpression of native or non-native carbohydrate active enzymes like glycosyl hydrolases or carbohydrate esterases. Some research in this area has focused on engineering plants that accumulate cell wall-degrading enzymes that are sequestered to organelles or only active at very high temperatures. The rationale being that, in order to avoid potential negative effects of cell wall modification during plant growth, the enzymes could be activated post-harvest

Lipoteichoic acid (LTA) is a key component of the cell wall of most Gram-positive bacteria and plays many structural and functional roles. In probiotic lactobacilli, the function of LTA in mediating bacteria/host cross-talk has been evidenced and it has been postulated that, owing to its anionic nature, LTA may play a role in toxic metal sequestration by these bacteria. However, studies on this last aspect employing strains unable to synthesise LTA are lacking. We have inactivated the LTA polymerase encoding gene ltaS in two different Lactobacillus plantarum strains. Analysis of LTA contents in wild-type and ltaS mutant strains corroborated the role of this gene as a major contributor to LTA synthesis in L. plantarum. The mutant strains displayed strain-dependent anomalous cell morphologies that resulted in elongated or irregular cells with aberrant septum formation. They also exhibited higher sensitivity to several stresses (osmotic and heat) and to antimicrobials that target the cell wall. The toxicity of inorganic [(Hg(II)] and organic mercury (methyl-Hg) was also increased upon ltaS mutation in a strain-dependent manner. However, the mutant strains showed 0 to 50% decrease in their capacity of Hg binding compared to their corresponding parental strains. This result suggests a partial contribution of LTA to Hg binding onto the cell surface that was dependent on the strain and the Hg form.

Although cell wall polymers play important roles in the tolerance of plants to abiotic stress, the effects of salinity on cell wall composition and metabolism in grasses remain largely unexplored. Here, we conducted an in‐depth study of changes in cell wall composition and phenolic metabolism induced upon salinity in maize seedlings and plants. Cell wall characterization revealed that salt stress modulated the deposition of cellulose, matrix polysaccharides and lignin in seedling roots, plant roots and stems. The extraction and analysis of arabinoxylans by size‐exclusion chromatography, 2D‐NMR spectroscopy and carbohydrate gel electrophoresis showed a reduction of arabinoxylan content in salt‐stressed roots. Saponification and mild acid hydrolysis revealed that salinity also reduced the feruloylation of arabinoxylans in roots of seedlings and plants. Determination of lignin content and composition by nitrobenzene oxidation and 2D‐NMR confirmed the increased incorporation of syringyl units in lignin of maize roots. Salt stress also induced the expression of genes and the activity of enzymes enrolled in phenylpropanoid biosynthesis. The UHPLC–MS‐based metabolite profiling confirmed the modulation of phenolic profiling by salinity and the accumulation of ferulate and its derivatives 3‐ and 4‐O‐feruloyl quinate. In conclusion, we present a model for explaining cell wall remodeling in response to salinity.

Resistance against antimicrobial peptides (AMPs) is often mediated by detoxification modules that rely on sensing the AMP through a BceAB-like ATP-binding cassette (ABC) transporter that subsequently activates a cognate two-component system (TCS) to mount the cell response. Here, the Lactococcus lactis ABC transporter YsaDCB is shown to constitute, together with TCS-G, a detoxification module that protects L. lactis against bacitracin and the bacteriocin Lcn972, both AMPs that inhibit cell wall biosynthesis. Initially, increased expression of ysaDCB was detected by RT-qPCR in three L. lactis resistant to Lcn972, two of which were also resistant to bacitracin. These mutants shared, among others, single-point mutations in ysaB coding for the putative Bce-like permease. These results led us to investigate the function of YsaDCB ABC-transporter and study the impact of these mutations. Expression in trans of ysaDCB in L. lactis NZ9000, a strain that lacks a functional detoxification module, enhanced resistance to both AMPs, demonstrating its role as a resistance factor in L. lactis. When the three different ysaB alleles from the mutants were expressed, all of them outperformed the wild-type transporter in resistance against Lcn972 but not against bacitracin, suggesting a distinct mode of protection against each AMP. Moreover, P ysaD promoter fusions, designed to measure the activation of the detoxification module, revealed that the ysaB mutations unlock transcriptional control by TCS-G, resulting in constitutive expression of the ysaDCB operon. Finally, deletion of ysaD was also performed to get an insight into the function of this gene. ysaD encodes a secreted peptide and is part of the ysaDCB operon. YsaD appears to modulate signal relay between the ABC transporter and TCS-G, based on the different response of the P ysaD promoter fusions when it is not present. Altogether, the results underscore the unique features of this lactococcal detoxification module that warrant

An ever-increasing world population together with industrial development at an accelerated pace have push scientists to identify promising bio-resources to produce food, feed and fuel in the framework of carbon-neutral bio-economy. Amongst the bio-resources available, there has been a growing interest in the exploitation of microalgae biomass as an alternative green feedstock. However, at this moment, the microalgae-derived products are not economically feasible on account of a low return in investment.One way to enhance the economic viability of microalgae production and utilization is to design effective and sustainable methods for the extraction of its components. To design such methods we need to understand the biology of the microalgae cell. N. oleoabundans, the studied green microalgae in this thesis, contains valuable components enclosed within a morphologically complex cell wall. Thus, before accessing the intracellular components the cell wall barrier needs to be deconstructed. The overall aim of this thesis was to generate in-depth insights into cell wall building blocks of N. oleoabundans. Fundamental knowledge on the physicochemical structure and the underlying molecular determinants of cell wall biosynthesis and modification are the main focus.In Chapter 1 of this thesis, we presented an introduction about the importance of microalgae as a promising renewable feedstock. Further, we described the enormous biodiversity among the cell walls of different life kingdoms and in particular Chlorophyta green microalgae.In Chapter 2, we have made a comprehensive characterization of the N. oleoabundans cell walls. The results showed that N. oleoabundans cell walls are composed of about 2.4.3% carbohydrates, 31.5% proteins, 22.2% lipids and 7.8% inorganic compounds. A rather scarce amount of glucose in the N. oleoabundans suggested that non-cellulosic polysaccharides may underpin the cell wall rigidity. We concluded in this chapter that N. oleoabundans cell walls a

Chlorella vulgais, a kind of micro-alagae, is an attracting feedstock for bioenergy production, such as biodiesel and biogas. But its tough cell wall structure is the main obstacle to efficiently extracting lipids and other biomass. Ionic liquid (IL) can be used to hydrolyze its cell-wall. However, due to its high cost and toxicity, it is important to recover IL as much as possible. Therefore, a method that can accurately measure the content of ILs, is urgently needed. In this work, two common methods that are used to measure the content of ILs: equimolar titration method and ultraviolet absorbance spectra were compared. The results show that equimolar titration method is not available for trace quantity analysis of ionic liquids as the endpoint of titration is hard to be identified at low IL content (<10 mg/L); while UV absorbance spectra method can be used at low IL contents, whereas, it may result in big deviations. To further improve the accuracy of UV absorbance spectra method, concentrating the sample could be a potential solution.

This study evaluated the relationship between cell wall breakdown, from Shiraz grapes harvested at three different ripeness levels and the colour and phenolics extracted during alcoholic fermentation into wines. Phenolic differences between the ripeness treatments were minimal after ¼ of the fermentation was completed. However, colour and phenolic content were significantly higher in finished wines made from 25°Brix grapes compared to those from 21°Brix and 23°Brix. Levels of grape cell wall polysaccharide deconstruction during fermentation was a determining correlative factor in relation to phenolic extractability. In this context, the de-pectination observed during ripening was found to enhance this deconstruction or “opening-up” of the grape pomace during fermentation, thus increasing the differential extraction of specific polyphenols, especially polymeric polyphenols, into the wines. Additionally, the degree of cell wall deconstruction seemed to play a role in the possible retention and extraction of specific grape proanthocyanidins, depending on their nature and polymer length.

Phenolic compounds play an important role in colour stability and sensory properties of red wine. This study evaluated berry skin cell wall composition and how this influences grape and wine phenolics at different ripeness levels (21°Brix, 23°Brix, and 25°Brix) over two consecutive vintages. The vintage effect was highly significant, especially in the pectin fraction of the grape cell walls and affected the concentrations of certain phenolics extracted. The climatic variance between the seasons might have influenced the differences observed in the grape cell wall compositions. Firstly, a higher grape and wine phenolic content, especially in polymeric phenols, was found in 2015 wines. Additionally, grape berry cell walls, especially at the earliest stages of ripening, were found to be more intact in 2015 than in 2016. Thus, a possible relationship was found between the degree of berry intactness, especially for pectin-rich components, and the corresponding phenolic extractability during the winemaking.

Mesophyll conductance (gm), the diffusion of CO2 from substomatal cavities to the carboxylation sites in the chloroplasts, is a highly complex trait driving photosynthesis (net CO2 assimilation, AN). However, little is known concerning the mechanisms by which it is dynamically regulated. The apoplast is considered as a ‘key information bridge’ between the environment and cells. Interestingly, most of the environmental constraints affecting gm also cause apoplastic responses, cell wall (CW) alterations and metabolic rearrangements. Since CW thickness is a key determinant of gm, we hypothesize that other changes in this cellular compartiment should also influence gm. We study the relationship between the antioxidant apoplastic system and CW metabolism and the gm responses in tobacco plants (Nicotiana sylvestris L.) under two abiotic stresses (drought and salinity), combining in vivo gas‐exchange measurements with analyses of antioxidant activities, CW composition and primary metabolism. Stress treatments imposed substantial reductions in AN (58–54%) and gm (59%), accompanied by a strong antioxidant enzymatic response at the apoplastic and symplastic levels. Interestingly, apoplastic but not symplastic peroxidases were positively related to gm. Leaf anatomy remained mostly stable; however, the stress treatments significantly affected the CW composition, specifically pectins, which showed significant relationships with AN and gm. The treatments additionally promoted a differential primary metabolic response, and specific CW‐related metabolites including galactose, glucosamine and hydroxycinnamate showed exclusive relationships with gm independent of the stress. These results suggest that gm responses can be attributed to specific changes in the apoplastic antioxidant system and CW metabolism, opening up more possibilities for improving photosynthesis using breeding/biotechnological strategies

Fungal pathogens are the major cause of decay during postharvest handling and storage of fresh produce. Among the plethora of different fungi causing decay, necrotrophic fungi represent the main threat to major fruit crops, such as citrus, pome, or stone fruits. Classically, plant necrotrophic fungi have been considered unsophisticated pathogens that kill host cells with the use of toxins and/or cell wall-degrading enzymes (CWDE). However, studies conducted in recent years, mainly with Botrytis cinerea Pers. and Sclerotinia sclerotiorum (Lib.) de Bary are changing this simplistic perception about necrotrophic fungi. Consequently, there is an increased interest in elucidating the pathogenicity mechanisms deployed by these fungi. A recent review covered the molecular aspects of the interactions between postharvest pathogenic fungi and fruits, attending to both the pathogen and the host (Tian et al., 2016). This chapter is more focused on the current knowledge of the molecular mechanisms deployed by necrotrophic postharvest fungi.

The aim of this study was to investigate the influence of the cell wall of the microalga Chlamydomonas reinhardtii (C. reinhardtii) on its anaerobic digestion (AD) by comparing the AD of C. reinhardtii 6145 and of its mutant without cell wall C. reinhardtii cw15, assessing simultaneously the influence of the cell wall on anaerobic co-digestion of these strains with a carbon-rich substrate, olive mill solid waste (OMSW). The OMSW is the main by-product from two-phase olive oil manufacturing process. Biochemical methane potential (BMP) tests of the sole substrates and different mixtures (OMSW-microalgae) (85%-15%, 75%-25%, 50%-50%) were carried out. The results showed that the cell wall was not hindrance and became an advantage by releasing intracellular biomass to be degraded slowly. The influence of the substrate composition in the mixtures of OMSW and Chlamydomonas reinhardtii (6145 and cw15) was assessed through the calculation of performance and kinetic parameters by using the Transference Function model. The mixture 50% OMSW-50% C. reinhardtii 6145 allowed the highest methane yield (542 ± 4 mL CH/g VS) and also resulted in one of the highest maximum methane production rates, Rmax (129 ± 3 mL CH/(g VS·d).

The lytic cassette of Lactococcus lactis prophage TP712 contains a putative membrane protein of unknown function (Orf54), a holin (Orf55), and a modular endolysin with a N-terminal glycoside hydrolase (GH_25) catalytic domain and two C-terminal LysM domains (Orf56, LysTP712). In this work, we aimed to study the mode of action of the endolysin LysTP712. Inducible expression of the holin-endolysin genes seriously impaired growth. The growth of lactococcal cells overproducing the endolysin LysTP712 alone was only inhibited upon the dissipation of the proton motive force by the pore-forming bacteriocin nisin. Processing of a 26-residues signal peptide is required for LysTP712 activation, since a truncated version without the signal peptide did not impair growth after membrane depolarization. Moreover, only the mature enzyme displayed lytic activity in zymograms, while no lytic bands were observed after treatment with the Sec inhibitor sodium azide. LysTP712 might belong to the growing family of multimeric endolysins. A C-terminal fragment was detected during the purification of LysTP712. It is likely to be synthesized from an alternative internal translational start site located upstream of the cell wall binding domain in the lysin gene. Fractions containing this fragment exhibited enhanced activity against lactococcal cells. However, under our experimental conditions, improved in vitro inhibitory activity of the enzyme was not observed upon the supplementation of additional cell wall binding domains in. Finally, our data pointed out that changes in the lactococcal cell wall, such as the degree of peptidoglycan O-acetylation, might hinder the activity of LysTP712. LysTP712 is the first secretory endolysin from a lactococcal phage described so far. The results also revealed how the activity of LysTP712 might be counteracted by modifications of the bacterial peptidoglycan, providing guidelines to exploit the biotechnological potential of phage endolysins within industrial

Under stress, isolated microspores are reprogrammed in vitro towards embryogenesis, producing doubled haploid plants that are useful biotechnological tools in plant breeding as a source of new genetic variability, fixed in homozygous plants in only one generation. Stress-induced cell death and low rates of cell reprogramming are major factors that reduce yield. Knowledge gained in recent years has revealed that initiation and progression of microspore embryogenesis involve a complex network of factors, whose roles are not yet well understood. Here, I review recent findings on the determinant factors underlying stress-induced microspore embryogenesis, focusing on the role of autophagy, cell death, auxin, chromatin modifications, and the cell wall. Autophagy and cell death proteases are crucial players in the response to stress, while cell reprogramming and acquisition of totipotency are regulated by hormonal and epigenetic mechanisms. Auxin biosynthesis, transport, and action are required for microspore embryogenesis. Initial stages involve DNA hypomethylation, H3K9 demethylation, and H3/H4 acetylation. Cell wall remodelling, with pectin de-methylesterification and arabinogalactan protein expression, is necessary for embryo development. Recent reports show that treatments with small modulators of autophagy, proteases, and epigenetic marks reduce cell death and enhance embryogenesis initiation in several crops, opening up new possibilities for improving in vitro embryo production in breeding programmes.

Cotyledon cells in kidney beans naturally encapsulate starch and proteins limiting the access of digestive enzymes to their substrates. In this study, we investigated the effect of cell wall on bean protein digestibility and its relationship with starch digestion. Results showed that proteins contained in the cytoplasmic matrix influence the rate at which starch is digested in-vitro. Confocal laser scanning microscopy revealed that storage proteins in the cytoplasm act as a second encapsulation system preventing starch digestion. This microstructural organization only affected starch since no changes in protein digestion rate or extent were observed due to the presence of starch granules. Fourier transform infrared spectroscopy revealed that cellular entrapment limited protein denaturation induced by thermal treatments. High concentrations of a fraction resistant to digestion were found in proteins that were heated when entrapped within intact cotyledon cells, compared to those thermally treated as bean flour.

Diffusion of fluorescently labeled dextran of varying molecular weight in wood pretreated by steam explosion was studied with a confocal microscope. The steam explosion experiments were conducted at relatively mild conditions relevant for materials biorefinery at a pressure of 14 bars for 10 min. The method of fluorescence recovery after photobleaching (FRAP) was used to perform diffusion measurements locally in the wood microstructure. It was found that the FRAP methodology can be used to observe differences in the diffusion coefficient based on localization in the microstructure, i.e., earlywood, latewood, and cell wall. Microscopic changes due to steam explosion were seen to increase diffusion of the smaller 3-kDa dextran diffusion probe in the earlywood, while the latewood structure was not affected in any significant way. Macroscopic changes to the structure in the form of ruptures due to the steam explosion pretreatment were observed to increase the rate of diffusion for the larger 40-kDa dextran probe.

Diffusion of fluorescently labeled dextran of varying molecular weight in wood pretreated by steam explosion was studied with a confocal microscope. The steam explosion experiments were conducted at relatively mild conditions relevant for materials biorefinery at a pressure of 14 bars for 10 min. The method of fluorescence recovery after photobleaching (FRAP) was used to perform diffusion measurements locally in the wood microstructure. It was found that the FRAP methodology can be used to observe differences in the diffusion coefficient based on localization in the microstructure, i.e., earlywood, latewood, and cell wall. Microscopic changes due to steam explosion were seen to increase diffusion of the smaller 3-kDa dextran diffusion probe in the earlywood, while the latewood structure was not affected in any significant way. Macroscopic changes to the structure in the form of ruptures due to the steam explosion pretreatment were observed to increase the rate of diffusion for the larger 40-kDa dextran probe.

BackgroundWe previously developed several strategies to engineer plants to produce cost-efficient biofuels from plant biomass. Engineered Arabidopsis plants with low xylan and lignin content showed normal growth and improved saccharification efficiency under standard growth conditions. However, it remains to be determined whether these engineered plants perform well under drought stress, which is the primary source of abiotic stress in the field.ResultsUpon exposing engineered Arabidopsis plants to severe drought, we observed better survival rates in those with a low degree of xylan acetylation, low lignin, and low xylan content compared to those in wild-type plants. Increased pectic galactan content had no effect on drought tolerance. The drought-tolerant plants exhibited low water loss from leaves, and drought-responsive genes (RD29A, RD29B, DREB2A) were generally up-regulated under drought stress, which did not occur in the well-watered state. When compared with the wild type, plants with low lignin due to expression of QsuB, a 3-dehydroshikimate dehydratase, showed a stronger response to abscisic acid (ABA) in assays for seed germination and stomatal closure. The low-lignin plants also accumulated more ABA in response to drought than the wild-type plants. On the contrary, the drought tolerance in the engineered plants with low xylan content and low xylan acetylation was not associated with differences in ABA content or response compared to the wild type. Surprisingly, we found a significant increase in galactose levels and sugar released from the low xylan-engineered plants under drought stress.ConclusionsThis study shows that plants engineered to accumulate less lignin or xylan are more tolerant to drought and activate drought responses faster than control plants. This is an important finding because it demonstrates that modification of secondary cell walls does not necessarily render the plants less robust in the environment, and it shows that substantial chan

Climate change has modified the behavior of climate variables, for this reason, pastures manifest a seasonal productive behavior, where the deposition of structural carbohydrates is modified and in some cases the absorption of minerals. The objective of this study was to characterize, in varieties of Cenchrus purpureus tolerant to drought, the chemical composition of leaves and stems at different ages of regrowth in conditions of intense seasonal drought. The experimental period covered the years 2013 to 2015, in the Experimental Station of Pastures and Forages of the Institute of Agricultural Research “Jorge Dimitrov”. In a completely randomized design with the factorial arrangement was used, and the dynamics of the chemical composition of leaves and stems of new varieties of C. purpureus were characterized, in different ages of regrowth and different climatic periods (rainy and not very rainy), and their combination (4 x 3 x 2). The interaction age of regrowth with climatic station affected the chemical composition of the leaves (p≤0.001), altering the content of cellulose (Cel), hemicellulose (Hcel), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellular content (CC), calcium (Ca) and silica (Si), while in the stems this interaction only affected the concentration of ADF. The isolated effect of the climatic season modified in leaves (p≤0.01) the content of phosphorus (P) and lignin (Lig), it stems the P content (p≤0.001). When the regrowth age varied, there was a modification of the chemical composition of the leaves (crude protein and Lig) and stems (crude protein). The new varieties of C. purpureus under conditions of degradation and intense seasonal drought showed a pattern of chemical behavior similar to that of tropical grasses, but with low contents of protein and phosphorus., El cambio climático ha modificado el comportamiento de las variables del clima, por esta razón, los pastos manifiestan un comportamiento productivo estacional, donde se modifica la deposición de carbohidratos estructurales, y en algunos casos la absorción de minerales. El objetivo de esta investigación fue caracterizar, en variedades de Cenchrus purpureus tolerantes a la sequía, la composición química de hojas y tallos a diferentes edades de rebrote en condiciones de sequía estacional. El periodo experimental abarcó del año 2013 al 2015, en la Estación Experimental de Pastos y Forrajes del Instituto de Investigaciones Agropecuarias “Jorge Dimitrov”. Se empleó un diseño completamente aleatorizado con arreglo factorial, y se caracterizó la dinámica de la composición química de hojas y tallos de nuevas variedades de C. purpureus, en diferentes edades de rebrote y diferentes períodos climáticos (lluvioso y poco lluvioso) y su combinación (4 x 3 x 2). La interacción edad de rebrote con estación climática afectó la composición química de las hojas (p≤0,001), alteró el contenido de celulosa (Cel), hemicelulosa (Hcel), fibra en detergente neutro (FDN), fibra en detergente ácido (FDA), contenido celular (CC), calcio (Ca) y sílice (Si), mientras que, en los tallos esta interacción solo afectó la concentración de FDA. El efecto aislado de la estación climática modificó en hojas (p≤0,01) el contenido de fósforo (P) y lignina (Lig), en tallos el contenido de P (p≤0,001). Cuando varió la edad de rebrote, hubo una modificación de la composición química de las hojas (proteína bruta y Lig) y de los tallos (proteína bruta). Las nuevas variedades de C. purpureus, bajo condiciones de degradación y sequía estacional, mostraron un patrón de comportamiento químico semejante al de las gramíneas tropicales, pero con bajos contenidos de proteína y fósforo.

BackgroundWe previously developed several strategies to engineer plants to produce cost-efficient biofuels from plant biomass. Engineered Arabidopsis plants with low xylan and lignin content showed normal growth and improved saccharification efficiency under standard growth conditions. However, it remains to be determined whether these engineered plants perform well under drought stress, which is the primary source of abiotic stress in the field.ResultsUpon exposing engineered Arabidopsis plants to severe drought, we observed better survival rates in those with a low degree of xylan acetylation, low lignin, and low xylan content compared to those in wild-type plants. Increased pectic galactan content had no effect on drought tolerance. The drought-tolerant plants exhibited low water loss from leaves, and drought-responsive genes (RD29A, RD29B, DREB2A) were generally up-regulated under drought stress, which did not occur in the well-watered state. When compared with the wild type, plants with low lignin due to expression of QsuB, a 3-dehydroshikimate dehydratase, showed a stronger response to abscisic acid (ABA) in assays for seed germination and stomatal closure. The low-lignin plants also accumulated more ABA in response to drought than the wild-type plants. On the contrary, the drought tolerance in the engineered plants with low xylan content and low xylan acetylation was not associated with differences in ABA content or response compared to the wild type. Surprisingly, we found a significant increase in galactose levels and sugar released from the low xylan-engineered plants under drought stress.ConclusionsThis study shows that plants engineered to accumulate less lignin or xylan are more tolerant to drought and activate drought responses faster than control plants. This is an important finding because it demonstrates that modification of secondary cell walls does not necessarily render the plants less robust in the environment, and it shows that substantial chan

Climate change has modified the behavior of climate variables, for this reason, pastures manifest a seasonal productive behavior, where the deposition of structural carbohydrates is modified and in some cases the absorption of minerals. The objective of this study was to characterize, in varieties of Cenchrus purpureus tolerant to drought, the chemical composition of leaves and stems at different ages of regrowth in conditions of intense seasonal drought. The experimental period covered the years 2013 to 2015, in the Experimental Station of Pastures and Forages of the Institute of Agricultural Research “Jorge Dimitrov”. In a completely randomized design with the factorial arrangement was used, and the dynamics of the chemical composition of leaves and stems of new varieties of C. purpureus were characterized, in different ages of regrowth and different climatic periods (rainy and not very rainy), and their combination (4 x 3 x 2). The interaction age of regrowth with climatic station affected the chemical composition of the leaves (p≤0.001), altering the content of cellulose (Cel), hemicellulose (Hcel), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellular content (CC), calcium (Ca) and silica (Si), while in the stems this interaction only affected the concentration of ADF. The isolated effect of the climatic season modified in leaves (p≤0.01) the content of phosphorus (P) and lignin (Lig), it stems the P content (p≤0.001). When the regrowth age varied, there was a modification of the chemical composition of the leaves (crude protein and Lig) and stems (crude protein). The new varieties of C. purpureus under conditions of degradation and intense seasonal drought showed a pattern of chemical behavior similar to that of tropical grasses, but with low contents of protein and phosphorus., El cambio climático ha modificado el comportamiento de las variables del clima, por esta razón, los pastos manifiestan un comportamiento productivo estacional, donde se modifica la deposición de carbohidratos estructurales, y en algunos casos la absorción de minerales. El objetivo de esta investigación fue caracterizar, en variedades de Cenchrus purpureus tolerantes a la sequía, la composición química de hojas y tallos a diferentes edades de rebrote en condiciones de sequía estacional. El periodo experimental abarcó del año 2013 al 2015, en la Estación Experimental de Pastos y Forrajes del Instituto de Investigaciones Agropecuarias “Jorge Dimitrov”. Se empleó un diseño completamente aleatorizado con arreglo factorial, y se caracterizó la dinámica de la composición química de hojas y tallos de nuevas variedades de C. purpureus, en diferentes edades de rebrote y diferentes períodos climáticos (lluvioso y poco lluvioso) y su combinación (4 x 3 x 2). La interacción edad de rebrote con estación climática afectó la composición química de las hojas (p≤0,001), alteró el contenido de celulosa (Cel), hemicelulosa (Hcel), fibra en detergente neutro (FDN), fibra en detergente ácido (FDA), contenido celular (CC), calcio (Ca) y sílice (Si), mientras que, en los tallos esta interacción solo afectó la concentración de FDA. El efecto aislado de la estación climática modificó en hojas (p≤0,01) el contenido de fósforo (P) y lignina (Lig), en tallos el contenido de P (p≤0,001). Cuando varió la edad de rebrote, hubo una modificación de la composición química de las hojas (proteína bruta y Lig) y de los tallos (proteína bruta). Las nuevas variedades de C. purpureus, bajo condiciones de degradación y sequía estacional, mostraron un patrón de comportamiento químico semejante al de las gramíneas tropicales, pero con bajos contenidos de proteína y fósforo.

The mango (Mangifera indica) is a woody perennial crop currently cultivated worldwide in regions with tropical and subtropical climates. Despite its importance, an essential process such as pollen development, and, specifically, cell wall composition that influences crosstalk between somatic cells and the male germline, is still poorly understood in this species and in the Anacardiaceae as a whole. A detailed understanding of this process is particularly important to know the effect of low temperatures during flowering on pollen development that can be a limiting factor for fertilization and fruit set. To fill this gap, we performed a thorough study on the cell wall composition during pollen development in mango. The results obtained reveal a clear differentiation of the cell wall composition of the male germline by pectins, AGPs and extensins from the early developmental stages during microsporogenesis and microgametogenesis reflecting a restricted communication between the male germline and the surrounding somatic cells that is very sensitive to low temperatures. The combination of the results obtained provides an integrated study on cell wall composition of the male germline in mango that reveals the crucial role of the sporophyte and the gametophyte and the vulnerability of the process to low temperatures.

Functional materials with high porosity and hierarchical structures are highly demanded for numerous material applications. In this study a magnetic hybrid material derived from wood and superparamagnetic iron oxide nanoparticles (SPIONs), was synthesized by microwave-assisted thermal decomposition. This novel in situ functionalization approach resulted in a homogeneous distribution of the integrated inorganic component within the entire complex wood cell wall structure, which was previously not achieved. In a detailed investigation based on confocal Raman microscopy imaging, transmission electron microscopy, and optical microscopy the precipitated phase and the resulting hybrid structure were characterized. Magnetic measurements revealed the impact of the anisotropic wood scaffold on the integrated magnetic functionality and confirmed the isotropic superparamagnetic characteristics of the in situ precipitated nanoparticles. Therewith, it is clearly demonstrated, that the anisotropic properties of the obtained hybrid material result from the particle organization in the given spruce wood structure and no alteration of particle properties is induced by the presence of the lignocellulosic material.

Microalgae have many advantages for the production of biogas by anaerobic digestion process. However, the anaerobic digestion process has been reported to be limited in the hydrolytic stage due to the specific characteristics of the cell wall components thus resulting in an inefficient conversion of biomass to biogas. Pre-treatments aim to achieve an increase in the biogas production by increasing solubilization. Enzymatic pretreatment is described as an environmentally-friendly process, due to the low energy consumption, great yield of freed, fermentable sugars from the biomass under light operational conditions, the absence of corrosive problems, and few derivatives produced. Within the category of enzymatic pretreatments, it might identify two types, which are related to the origin of the enzymes and which may be classified as endogenous enzymes, and commercial exogenous enzymes. It should also be considered that enzyme production costs for commercial enzymes might be a negative factor in the process. The objective of the present review is to analyze and discuss the application of digestive pretreatments on the solubilization of microalgae, with a focus on the cell wall, and its relation to biogas production increase.

Isolated bean cells were used to understand the contribution of cell wall and cytoplasmic matrix on starch digestibility. Cotyledon cells were treated enzymatically and mechanically to reduce the level of cell intactness. SEM and chemical characterization revealed that enzymatic treatment modified cell wall thickness and porosity without altering the cytoplasmic matrix, whereas mechanical treatment completely disrupted cell structure. Decreasing cell intactness increased the rate but not the extent of starch digestion in-vitro. It was concluded that cell wall serves as a permeable barrier limiting the access of digestive enzymes. Cytoplasmic matrix, on the other hand, reduced further the accessibility of amylase to starch affecting its hydrolysis rate. In addition, it was proven that cell structural changes, if any, occurring during digestion had no effect on starch hydrolysis.

Lactococcus lactis is widely used as a starter in the manufacture of cheese and fermented milk. Its main role is the production of lactic acid, but also contributes to the sensory attributes of cheese. Unfortunately, the diversity of suitable strains to be commercialized as dairy starters is limited. In this work, we have applied adaptive evolution under cell envelope stress (AE-CES) as means to provide evolved L. lactis strains with distinct physiological and metabolic traits. A total of seven strains, three of industrial origin and four wild nisin Z-producing L. lactis, were exposed to subinhibitory concentrations of Lcn972, a bacteriocin that triggers the cell envelope stress response in L. lactis. Stable Lcn972 resistant (Lcn972R) mutants were obtained from all of them and two mutants per strain were further characterized. Minimal inhibitory Lcn972 concentrations increased from 4- to 32-fold compared to their parental strains and the Lcn972R mutants retained similar growth parameters in broth. All the mutants acidified milk to a pH below 5.3 with the exception of one that lost the lactose plasmid during adaptation and was unable to grow in milk, and two others with slower acidification rates in milk. While in general phage susceptibility was unaltered, six mutants derived from three nisin Z producers became more sensitive to phage attack. Loss of a putative plasmid-encoded anti-phage mechanism appeared to be the reason for phage susceptibility. Otherwise, nisin production in milk was not compromised. Different inter- and intra-strain-dependent phenotypes were observed encompassing changes in cell surface hydrophobicity and in their autolytic profile with Lcn972R mutants being, generally, less autolytic. Resistance to other antimicrobials revealed cross-protection mainly to cell wall-active antimicrobials such as lysozyme, bacitracin, and vancomycin. Finally, distinct and shared non-synonymous mutations were detected in the draft genome of the Lcn972R mutants. De

Stress-induced microspore embryogenesis is an in vitro system in which the haploid microspore is reprogramed by the application of stress treatments and, as a totipotent cell, enters into an embryogenesis pathway, producing double-haploid (DH) embryos and plants. DHs are important biotechnological tools in plant breeding programs, widely used by companies, as a source of new genetic variability, fixed in complete homozygous plants in only one generation step. However, their applications are limited in many crop and forest species due to low or nulle efficiency. Microspore embryogenesis is also a convenient system to analyze the cellular processes underlying cell reprogramming, totipotency acquisition and embryogenesis. In the last years, investigation on stress-induced microspore embryogenesis has unveiled the involvement of several cellular processes like autophagy, cell death, epigenetic modifications, auxin and cell wall remodeling, whose role is not yet completely elucidated. In the present chapter, we review recent findings on the determinant factors that underlie stress-induced microspore embryogenesis induction and progression. These findings have provided new insights into the regulating mechanisms of microspore embryogenesis initiation and progression, opening up new intervention pathways through pharmacological treatments with small bioactive compounds (autophagy, epigenetic and auxin modulators), very promising to enhance in vitro embryo production yield for breeding programs of crop and forest species, especially for those recalcitrant.

The epidermis of aerial plant organs is thought to be limiting for growth, because it acts as a continuous load-bearing layer, resisting tension. Leaf epidermis contains jigsaw puzzle piece-shaped pavement cells whose shape has been proposed to be a result of subcellular variations in expansion rate that induce local buckling events. Paradoxically, such local compressive buckling should not occur given the tensile stresses across the epidermis. Using computational modeling, we show that the simplest scenario to explain pavement cell shapes within an epidermis under tension must involve mechanical wall heterogeneities across and along the anticlinal pavement cell walls between adjacent cells. Combining genetics, atomic force microscopy, and immunolabeling, we demonstrate that contiguous cell walls indeed exhibit hybrid mechanochemical properties. Such biochemical wall heterogeneities precede wall bending. Altogether, this provides a possible mechanism for the generation of complex plant cell shapes., Bio4Energy

The plant cell wall is composed of many complex polysaccharides. The composition and structure of the polysaccharides affect various cell properties including cell shape, cell function and cell adhesion. PACE (Polysaccharide Analysis using Carbohydrate gel Electrophoresis) uses a simple, rapid technique to analyze polysaccharide quantity and structure (Goubet et al., Anal Biochem 300:53-68, 2002).

The plant cell wall is composed of many complex polysaccharides. The composition and structure of the polysaccharides affect various cell properties including cell shape, cell function and cell adhesion. PACE (Polysaccharide Analysis using Carbohydrate gel Electrophoresis) uses a simple, rapid technique to analyze polysaccharide quantity and structure (Goubet et al., Anal Biochem 300:53-68, 2002).

Plastic deformation of ARMCO iron processed by ECAP up to a maximum equivalent strain of sixteen (i.e., 1, 4, 8, and 16 ECAP passes) following route Bc was investigated by analyzing its microstructure and the stress-strain curves obtained after tensile tests at different levels of deformation. Three values of deformation (two in the plastic region taking into account the modified Crussard-Jaoul analysis and one after failure) were considered. Fractions of LAGB and HAGB, grain size and grain aspect ratio were calculated and compared for the different ECAP passes and tensile deformation levels. The dislocation density evolution calculated by the Bergström model for both the tensile curves and the ECAP curve showed a higher increase in the amount of dislocations during the initial stages of deformation than at higher values of deformation due to higher probabilities of dislocations annihilation. The strain hardening exponents calculated via the Bergström model for each ECAP pass shows that there is a continuous decrease in the strain hardening capacity until the eighth pass where a small increase with a subsequent stabilization was found. The dislocation densities calculated by the Estrin model presented a good correlation with values reported in bibliography for iron especially with those calculated by X-ray diffraction. This latter model predicted well the strain hardening evolution for stages III, IV and V for ARMCO iron processed by ECAP, where the main increments in hardening for stages IV and V were coming from the cell interiors., Preprint

Somatic embryogenesis is considered a convenient tool for investigating the regulating mechanisms of embryo formation; it is also a feasible system for in vitro regeneration procedures, with many advantages in woody species. Nevertheless, trees have shown recalcitrance to somatic embryogenesis, and its efficiency remains very low in many cases. Consequently, despite the clear potential of somatic embryogenesis in tree breeding programs, its application is limited since factors responsible for embryogenesis initiation have not yet been completely elucidated. In the present work, we investigated key cellular factors involved in the change of developmental program during leaf somatic embryogenesis initiation of white oak (Quercus alba), aiming to identify early markers of the process. The results revealed that pectin esterification, auxin accumulation and DNA demethylation were induced during embryogenesis initiation and differentially found in embryogenic cells, while they were not present in leaf cells before induction or in non-embryogenic cells after embryogenesis initiation. These three factors constitute early markers of leaf embryogenesis and represent processes that could be interconnected and involved in the regulation of cell reprogramming and embryogenesis initiation. These findings provide new insights into the mechanisms underlying plant cell reprogramming, totipotency and embryogenic competence acquisition, especially in tree species for which information is scarce, thus opening up the possibility of efficient manipulation of somatic embryogenesis induction.

BACKGROUND: Metal sequestration by bacteria has been proposed as a strategy to counteract metal contamination in foodstuffs. Lactobacilli can interact with metals, although studies with important foodborne metals such as inorganic [Hg(II)] or organic (CH3Hg) mercury are lacking. Lactobacilli were evaluated for their potential to bind these contaminants and the nature of the interaction was assessed by the use of metal competitors, chemical and enzymatical treatments, and mutants affected in the cell wall structure. RESULTS: Lactobacillus strains efficiently bound Hg(II) and CH3Hg. Mercury binding by Lactobacillus casei BL23 was independent of cell viability. In BL23, both forms of mercury were cell wall bound. Their interaction was not inhibited by cations and it was resistant to chelating agents and protein digestion. Lactobacillus casei mutants affected in genes involved in the modulation of the negative charge of the cell wall anionic polymer lipoteichoic acid showed increased mercury biosorption. In these mutants, mercury toxicity was enhanced compared to wild-type bacteria. These data suggest that lipoteichoic acid itself or the physicochemical characteristics that it confers to the cell wall play a major role in mercury complexation. CONCLUSION: This is the first example of the biosorption of Hg(II) and CH3Hg in lactobacilli and it represents a first step towards their possible use as agents for diminishing mercury bioaccessibility from food at the gastrointestinal tract. © 2017 Society of Chemical Industry