Tailored optimization for specific climatic conditions can provide several percent annual energy gain over standard approaches. It was also shown that resistance losses due to cell interconnection impact not only the module efficiency but also the temperature coefficient of modules, highlighting the stronger need for low-resistance interconnection in hot climates [Haschke].
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Boccard , L. Antognini, J. Cattin, J. Fioretti, J. Haschke, R. Monnard, E. Rucavado, S. Tomasi, B. Paviet-Salomon, Q. Jeangros, J. Haschke, G. Christmann, L. Barraud, A. Descoeudres, J. Seif, S. Nicolay, M. Despeisse, S. De Wolf, and C. Haschke, J. P: Seif, Y. Riesen, A. Tomasi, J. Cattin, L. Tous, …, and C.
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Kobayashi, S. De Wolf, J. Levrat, G. Christmann, A. Descoeudres, S. Despeisse, Y. Watabe, and C. Seif, A. Descoeudreas, G. Crystalline silicon photovoltaics is the most widely used photovoltaic technology. Crystalline silicon photovoltaics are modules built using crystalline silicon solar cells c-Si , developed from the microelectronics technology industry. Crystalline silicon solar cells have high efficiency, making crystalline silicon photovoltaics an interesting technology where space is at a premium.
The cell wall composition of B. In addition, the Si uptake system and the levels of Si accumulation in shoot tissues are similar to those in barley, maize and wheat.
Together these properties make B. In the present work, we have used wild-type and low - silicon 1 mutant Bdlsi1 - 1 plants of B. We have studied the organ-specific deposition of Si in the cell walls and its effect upon cell wall polymer profiles at the ripening stage. Compositional changes associated with low Si levels in the mature plants were characterized with the overall intention to link them with the efficiency of enzymatic digestibility.
We demonstrate that cell walls of low-Si plants exhibit multiple compositional alterations, most likely affecting the linkage of the individual polymers within the cell wall network. However, as will be shown, these changes have minor or no effects on the saccharification potential of the biomass. Thereafter, the seeds were placed in pots containing soil Pindstrup Substrate NO. At the ripening stage, the sampled plants were subdivided into: i leaf blades and sheaths; ii stems; and iii spikelets heads , which included all reproductive organs, meaning flowers, seeds and bracts seed covers.
At senescence maturity , entire shoots, including all the above-ground organs, i. Cell wall material alcohol insoluble residue, AIR was prepared in biological triplicates as described by [ 33 ] with adaptations. The pellet was left to dry and AIR was obtained.
Starch was removed by enzymatic digestion according to [ 34 ]. The analyses were performed on samples harvested at the ripening growth stage and at maturity as described below. The resulting solution was filtered through a membrane filter having a pore size of 0. After addition of 0. Silica residues phytoliths were recovered from the filters, washed several times with water followed by acetone, and left to air dry. PDMPO is used to measure the pH of acidic organelles; however, it has been shown to produce green fluorescence upon interaction with silica surfaces, but not silicic acid [ 6 , 35 ].
Each sample was examined under a fluorescence microscope Leica DMB. Non-cellulosic polysaccharide composition and cellulose content were determined following [ 36 ] with modifications. TFA releases primarily non-cellulosic polysaccharides; however, also parts of cellulose from regions containing kinks or dislocations will be hydrolyzed.
The supernatant was filtered with 0. The separated monosaccharides were quantified using calibration with monosaccharide standards l -arabinose, l -rhamnose, d -xylose, d -galactose, d -glucose, d -glucuronic and d -galacturonic acid Sigma. The content of intact cellulose microfibrils in the TFA-resistant pellet was quantified based on the method reported by [ 37 ].
Cellulose content was determined in triplicate for each sample. The analysis was performed essentially according to the method reported by [ 38 , 39 ]. Each extraction was done in triplicates and pooled to one sample. The probes used in this study are specific for plant cell wall polymers and listed in Additional file 1 : Table S1.
The signal strength was quantified using Array-Pro Analyzer 6. The degree of methylesterification was analysed by saponification of AIR followed by enzymatic oxidation of methanol released by alcohol oxidase, as described by [ 40 , 41 ] with modifications. Afterwards, the solution was neutralized with HCl and centrifuged.
Solar cells combining silicon with perovskite have achieved record efficiency of 25.2 percent
Ground barley and oat flour, provided by the manufacturer, served as reference material. Mixed-linkage glucan content was determined in triplicate for each sample. The sections were then washed two times with PBS stained with Calcofluor 0. All sections were scanned with the same settings. The sections were placed in the drop of solution, incubated app.
The concentration of acetyl bromide lignin was determined according to the method described by [ 42 ]. After complete digestion, samples were cooled down and cleared by centrifugation. The lignin analysis was performed in triplicate for each sample. The straw or entire shoots of mature plants were pyrolyzed in duplicates in random order. Only total ion chromatogram TIC peak areas of compounds with no or insignificant co-elution were used in calculations. All compounds used for calculating monolignol and hydroxycinnamate ratios were identified by authentic standards or published mass spectra [ 44 ].
The compounds were grouped according to methoxylation into H, G or S. Monolignol ratios were calculated as the peak area of the specific monolignol in proportion to the total peak area of the three monolignols. Analogously, the hydroxycinnamate ratio was calculated. Pretreatments and enzymatic saccharification were performed on mature straw and entire shoot samples, following the method described by [ 39 ]. Dry material was ground and distributed using an automated sample preparation robotic system Labman Automation Ltd. The plates were sealed with Teflon tape with a little hole above each well, placed on a heating block and further sealed with a thin aluminium plate and a Teflon plate to ensure a gas tight enclosure.
Thereafter, the system was cooled down to room temperature prior to enzyme addition. The hydrolyzed samples were filtered through 0. Separation and determination of the glucose and xylose in the filtrates were carried out by an Ultimate HPLC Dionex, Germering, Germany equipped with a refractive index detector Shodex, Tokyo, Japan.
The low - silicon 1 mutant Bdlsi1 - 1 plants used in this study carry a mutation in the Si influx transporter BdLSI1 , localized in the roots. No phenotypic consequences were observed as the morphology and development of the Bdlsi1 - 1 plants were similar to the wild-type plants [ 29 ]. However, the average weight of the mature de-hulled seeds was reduced in the mutant plants despite the fact that the total yield of spikelets was comparable to that of the wild type [ 29 ]. First, we harvested wild-type and mutant plants at the ripening growth stage and at maturity to quantify non-phytolith Si.
Microwave-assisted acid digestion of the wild-type and Bdlsi1 - 1 plant material resulted in insoluble phytoliths that were isolated by filtration and further labelled with a silica-specific fluorescent dye Additional file 2 : Figure S1. The phytoliths varied in degree of silicification as indicated by the intensity of fluorescence Additional file 2 : Figure S1. The wild-type material contained substantially more phytoliths in all the analysed organs than did the mutant Additional file 2 : Figure S1.
The silicon present in the filtrate after acid digestion represented the pool of amorphous Si and Si chemically bound with cell wall polysaccharides, together designated as non-phytolith Si. This pool accounted in all cases for less than 0. At the ripening stage, the Si concentrations in the leaves and spikelets of the Bdlsi1 - 1 plants were two and threefold lower, respectively, than in the wild type Fig.
The organ having the largest proportion of Si associated with the cell walls, i. Concentrations of structural mineral elements in cell wall material of wild type WT and Bdlsi1 - 1 mutant plants. Material was harvested at two growth stages: i ripening a , c , e and ii maturity senescence b , d , f. At maturity, either entire shoots all vegetative and generative above-ground organs or straw leaves, leaf sheaths and stems were harvested.
Silicon distribution among organs and their cell walls in wild-type and mutant plant harvested at the ripening stage. Data show the average Si content in different organs of wild-type and mutant plants and the proportion of this Si present in non-phytolith form in cell wall material. Apart from Si, boron B and calcium Ca were also quantified as these elements play important structural roles within the cell wall by interacting with pectins.
Hemicelluloses and pectins constitute a large part of the cell wall structure and form together a fraction of non-cellulosic polysaccharides [ 45 , 46 ]. Here, we characterized the composition of monosaccharides associated with pectins rhamnose, galacturonic acid and galactose and hemicelluloses arabinose, glucose, xylose and glucuronic acid that were released from the cell walls following hydrolysis with trifluoroacetic acid TFA. The analysis revealed compositional variations among the organs, growth stages as well as alterations between the wild type and the mutant Fig.
Monosaccharide composition of non-cellulosic polysaccharides in cell walls of wild type WT and Bdlsi1 - 1 plants. Cell walls CW were isolated from leaves, stems and spikelets of B. The concentrations of arabinose and galacturonic acid in cell walls of the leaves were significantly lower in the Bdlsi1 - 1 mutant plants than in the wild type Fig. The same was the case for galactose and glucose in the spikelets Fig. Rhamnose was the least abundant monosaccharide detected in the cell walls of B. Expressed as arabinose to xylose ratio, the mutant had a slightly, but significantly, higher ratio of 0.
The concentration of TFA-extractable glucose was substantially reduced in the entire shoots of the mutant plants at maturity Fig. This corresponded with a decreased concentration of glucose in mutant spikelets at the ripening stage, while the concentrations in leaves and stems were similar to the wild type Fig. To identify the potential sources of alterations in the individual monomers building the non-cellulosic polysaccharides Fig. This method gives information about extractable cell wall glycans that are released in two consecutive extractions. The first fraction obtained following extraction with cyclohexane diamine tetraacetic acid CDTA; Fig.
Characterization of the pectin-rich fractions in wild-type WT and Bdlsi1 - 1 plants. Plants were harvested at the ripening stage of growth and at maturity and subdivided as previously described. The antibody names and their corresponding epitopes are indicated on the Y -axis. Antibodies that did not show signal for all the samples are not included in the heatmap, but listed in Additional file 1 : Table S1. Characterization of polysaccharides in hemicellulose in wild-type WT and Bdlsi1 - 1 plants.
The antibodies that did not show signal for all the samples tested are not included in the heatmap Additional file 1 : Table S1. Concentrations of mixed-linkage glucans MLG were determined in the wild-type and the Bdlsi1 - 1 plants at the ripening growth stage b and at maturity c using a lichenase-based assay. Images are overlaid with signal of Calcofluor counterstain blue outlining the cell walls.
Arrowhead indicates stronger LM12 signal in parenchymatic cells of Bdlsi1 - 1 stems. In grasses, pectins account for a relatively low proportion of the cell walls, but their main constituents, rhamnose and galacturonic acid, were nevertheless detected in all of the analysed B. Several pectin epitopes, mainly structures of homogalacturonans HG and rhamnogalacturonan-I RG-I , were also found in material harvested at both growth stages Figs.
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In our study, HG was detected with a range of monoclonal antibodies mAbs that recognize subtle differences in methylesterification patterns. At the ripening stage, leaves had the highest relative abundance of HG among the organs, and the intensity of several mAbs recognizing HG was lower in the Bdlsi1 - 1 leaves compared to the wild type Fig. To address this, we measured the degree of methylesterification DM of HG using an enzymatic assay. The DM in all the straw samples was comparable between the wild type and mutant and did not change from ripening to maturity Fig.
We identified the presence of RG-I in B. The epitopes were detected in all the samples, mostly in the fraction extracted with NaOH Figs. In leaves, the abundance of the epitope of the RG-I backbone was much higher in the Bdlsi1 - 1 samples, while mAbs recognizing both branched and linear arabinose chains showed lower signal relative to the wild type Figs. Several epitopes of AGPs and extensins were detected in both the CDTA and NaOH extractable fractions, suggesting varying nature and strength of their bonds with the cell wall components.
As expected, the extraction of B. At the ripening stage, the signal for the MLG epitope was higher in the stems and lower in the spikelets of the Bdlsi1 - 1 mutant compared to the wild type, whereas at maturity, the abundance was relatively lower in both the straw and entire shoots of Bdlsi1 - 1 Fig. Using a specific assay to quantify MLG, we observed that at the ripening stage MLG was present in much higher concentrations in the spikelets than in the leaves and stems Fig. From ripening to maturity, the MLG concentrations in all the samples increased up to several-fold Fig.
In grasses, arabinose residues of arabinoxylans AX can be modified via binding of ferulic acid FA that may bridge two adjacent AX molecules, but also cross-link hemicelluloses and lignin [ 48 ]. The presence of FA in the samples was detected by the LM12 antibody recognizing epitopes of polymers modified with FA.
The signal for the LM12 antibody was detected only in the CDTA fraction, and the relative intensity observed in the mutant leaves and stems sampled at the ripening stage was lower compared to the wild type Fig. The analysis of the mature material showed no signal for the LM12 antibody in the straw samples Fig. However, an LM12 signal was obtained in the entire shoots, where the wild type showed much higher relative abundance than Bdlsi1 - 1 Fig. To further explore this difference, we performed immunolocalization using the LM12 antibody.
While we did not succeed to obtain images for leaves, immunolabeling of the stem sections in the wild type revealed a strong fluorescence signal in the lignified sclerenchyma cells and in the xylem vessels Fig. The corresponding tissues in the Bdlsi1 - 1 mutant showed an overall reduction of the LM12 signal although with a relative intensification of the signal appearing in less lignified parenchymatic cells Fig.
The residual pellet after TFA hydrolysis of cell wall material consists mostly of intact cellulose fibrils. The cellulose concentration in the straw at both the ripening growth stage and at maturity was slightly, but significantly higher in the Bdlsi1 - 1 mutant compared to the wild type Fig. The same was the case for entire shoots at the ripening stage Fig.
Concentrations of cellulose across organs and developmental stages in the wild-type and Bdlsi1 - 1 mutant. The concentration of intact cellulose microfibrils in the TFA-resistant pellet was quantified in the wild-type WT and the Bdlsi1 - 1 plants sampled at the ripening stage a and maturity senescence b.
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To study lignin accumulation in the tissues of B. At the ripening stage, the lignin concentrations varied between the organs Fig. The lignin concentrations in all the organs sampled at the ripening stage of growth were comparable between the wild type and the mutant Fig. At maturity, the lignin concentration in the straw was similar for the wild type and mutant and similar to the values in the straw at the ripening growth stage Fig. On the other hand, the entire shoots of Bdlsi1 - 1 plants sampled at maturity contained significantly more lignin than the wild-type plants Fig.
Thus, the mature plants of the mutant contained relatively more lignin in the spikelets compared with the wild type. The concentrations of acetyl bromide soluble lignin were quantified in the wild-type and the Bdlsi1 - 1 sampled at the ripening growth stage a and maturity b. The composition of hydroxycinnamic acids in mature straw f and entire shoots g was quantified analogously to the lignin composition. Lignin quantification using the acetyl bromide method showed that stems were highly lignified organs in B. To compare the distribution of lignin in stems of the Bdlsi1 - 1 and the wild-type plants, we used histochemical staining with phloroglucinol Wiesner method Fig.
We detected the highest level of lignification in the xylem cell walls, bundle sheaths and interfascicular fibres Fig. Stems of the Bdlsi1 - 1 mutant, collected at the ripening stage displayed increased red-hued staining relative to the wild type Fig. This colour change appeared particularly in the interfascicular region Fig. Only the samples harvested at maturity were analysed as plants here have undergone full lignification.
Small amounts of H units were also detected Fig. Only the straw fraction differed in monolignol composition between the mutant and the wild type Fig. The wild-type plants had comparable amounts of G and S units in the straw, whereas the Bdlsi1 - 1 mutant had slightly higher content of S units and lower amount of G units than the wild type Fig. These differences were not apparent in the entire shoots due to the influence of spikelets Fig.