Quantitative Isolation of Hemicelluloses and Summative Analysis of Wood

Comparison of Lignocellulose Nanofibrils Extracted from Bamboo Fibrous and Parenchymal Tissues and the Properties of Resulting Films

Bamboo is composed of thick-walled fibrous tissue and thin-walled parenchymal tissue. To compare the energy consumption of preparing lignocellulose nanofibrils (LCNF) from these bamboo tissues, the crystallinity, sol. viscosity, morphology and mechanical properties of LCNF at different preparation stages were characterized in detail. It required at least nine homogenization cycles for dissociating the fibrous tissue, but only six cycles for the parenchymal tissue. The average diameter of LCNF isolated from fibrous and parenchymal tissues was 45.1 nm and 36.2 nm, respectively. The tensile strength of the LCNF film prepared from parenchymal tissue reached 142.46 MPa, whereas the film from fibrous tissue reached only 122.82 MPa. Additionally, a metal organic framework (MOF) was used to produce MOF-LCNF film with enhanced UV protection and antibacterial properties. The results indicated that the energy consumption for preparing LCNF from parenchymal tissue is significantly lower than that for preparing LCNF from fibrous tissue. This study offers a low-cost and eco-friendly method for preparing LCNF, promoting the precise utilization of different tissues from bamboo based on their unique characteristics.

Rhytidome- and cork-type barks of holm oak, cork oak and their hybrids highlight processes leading to cork formation

BACKGROUND

The periderm is basic for land plants due to its protective role during radial growth, which is achieved by the polymers deposited in the cell walls. In most trees, like holm oak, the first periderm is frequently replaced by subsequent internal periderms yielding a heterogeneous outer bark made of a mixture of periderms and phloem tissues, known as rhytidome. Exceptionally, cork oak forms a persistent or long-lived periderm which results in a homogeneous outer bark of thick phellem cell layers known as cork. Cork oak and holm oak distribution ranges overlap to a great extent, and they often share stands, where they can hybridize and produce offspring showing a rhytidome-type bark.

RESULTS

Here we use the outer bark of cork oak, holm oak, and their natural hybrids to analyse the chemical composition, the anatomy and the transcriptome, and further understand the mechanisms underlying periderm development. We also include a unique natural hybrid individual corresponding to a backcross with cork oak that, interestingly, shows a cork-type bark. The inclusion of hybrid samples showing rhytidome-type and cork-type barks is valuable to approach cork and rhytidome development, allowing an accurate identification of candidate genes and processes. The present study underscores that abiotic stress and cell death are enhanced in rhytidome-type barks whereas lipid metabolism and cell cycle are enriched in cork-type barks. Development-related DEGs showing the highest expression, highlight cell division, cell expansion, and cell differentiation as key processes leading to cork or rhytidome-type barks.

CONCLUSION

Transcriptome results, in agreement with anatomical and chemical analyses, show that rhytidome and cork-type barks are active in periderm development, and suberin and lignin deposition. Development and cell wall-related DEGs suggest that cell division and expansion are upregulated in cork-type barks whereas cell differentiation is enhanced in rhytidome-type barks.

Polysaccharides and lignin from oak wood used in cooperage: Composition, interest, assays: A review

It is widely accepted that alcoholic beverage quality depends on their ageing in premium quality oak wood. From the choice of wood to beverage ageing, through the different steps in cask manufacturing, many factors should be considered. One of the biggest challenge in cooperages is to take into account all these factors. Most of the studies are interested in phenolic compounds, extracted during ageing and especially involved in wine oxidation, colour, and sensory properties such as astringency and bitterness. Oak aroma volatile compounds have also been the subject of numerous studies. These compounds of interest are part of low molecular weight compounds which represent 2%-10% of oak wood composition. However, three polymers constitute the main part of oak wood: cellulose, hemicellulose and lignin. As far as we are aware, few studies concerning the role of these major macromolecules in oak wood have been published previously. This article reviews oak wood polysaccharides and lignin, their potential interest and different assays used to determine their content.

Diurnal differences in the supply of glucomannans and xylans to innermost surface of cell walls at various developmental stages from cambium to mature xylem in Cryptomeria japonica

We investigated the diurnal differences in the innermost surface of tracheid cell walls at various developmental stages from cambium to mature xylem. Cryptomeria japonica saplings were cultivated in a growth chamber with a light cycle set at 14 h of light and 10 h of darkness. Samples were collected from the saplings during both the light and dark periods. The innermost surface of cell walls was immunogold-labeled with anti-glucomannan or anti-xylan antiserum and was observed by field emission scanning electron microscopy. Diurnal differences in the aspect of the innermost surface of cell walls were seen only in S(2)-layer-forming tracheids; cellulose microfibrils were clearly evident during the light period, and amorphous material containing glucomannans and xylans was prevalent during the dark period. Cellulose microfibrils were present at the primary-wall formation and S(1)-layer-forming stages, and many warts were observed in the mature tracheids, regardless of the time of sampling. The densities of labeled glucomannans on the innermost surface of cell walls in S(1)- and S(2)-forming tracheids and of labeled xylans in S(2)-forming tracheids during the dark period were significantly higher than those during the light period. These results suggest a diurnal periodicity in the supply of cell wall matrix containing hemicellulose to the innermost surface of developing secondary walls.