Lignin deposition

At3g06550 - are deficient in wall-bound acetate. It would be interesting to test their resistance, lignin depositions and other physiological parameters under the influence of pathogens. It may be that these experiments will make clear the role of polysaccharide acetylation. 

A clear understanding of lignin deposition in the cell wall is not yet possible, but a number of facts are known. Lignin precursors of the phenylglucoside type are formed either in the region of the cambium (the zone of new cell synthesis) or within the lignifying cell itself. Lignification is thus initiated in the differentiated wood cells from the primary walls adjacent to the cell corners and then extends into the inter-cellular area, the lamella, and thereafter to the primary and secondary cell walls. 

Rogers, L. A., and Campbell, M. M., 2004, The genetic control of lignin deposition during plant growth and development, New Phytol. 164 17-30. 

Sibout, R., Baucher, M., Gatineau, M., Van Doorsselaere, J., Mila, L, Pol-let, B., Mabaa, B., Pilatec, G., Lapierree, C., Boerjand, W. and Jouanin L. (2002) Expression of a poplar cDNA encoding a ferulate-5-hydroxylase/ coniferaldehyde 5-hydroxylase increases S lignin deposition in Arabidopsis thaliana. Plant Physiol. Biochem., 40,1087-96. 

ABSTRACT Plant raw processing via acid hydrolysis is widely spread in Russia. Hydrolysis lignin is a large scale waste of this processing. In Russia hydrolysis lignin deposits mount to more than 1 million tons, Hydrolysis lignin contains 60-80% carbon and is a promising raw for production of adsorbents. 

Interestingly, the amount of cell wall lignin deposition in the vascular apparatus can vary from a few percent to approximately 30% depending on the plant species, this in turn depending on whether they are of nonwoody or woody character. Lignins are, however, essentially absent from algae, true aquatic plants, and basal land... 

AtOMTI mutant, but its over-expression did not lead to an increase in S lignin deposition. These data indicate that, unlike F5H, COMT is not a major control point in S lignin biosynthesis. On the other hand, C4H-F5H plants do incorporate 5HG units into their lignin, indicating that COMT does become a rate limiting step in S lignin biosynthesis when F5H is over-expressed. 

It is known that the cell walls consist of various layers the primary wall (P), the secondary wall which is divided into three sublayers (the outer SI, middle S2, and inner S3), and the midlle lamella (ML). Lignin deposition proceeds in different phases, each preceded by the deposition of carbohydrates, and starts at the cell comers in the region of the middle lamella and the primary wall when SI formation has initiated. When the formation of the polysaccharide matrix of the S2 layer is completed, lignification proceeds through the secondary wall. The bulk of lignin is... 

The chemical nature of the carbohydrate matrix and the orientation of the cellulose microfibrils influence lignin deposition. In the middle lamella and the primary wall, lignin forms spherical structures, whereas in the secondary wall, lignin forms lamellae that follow the orientation of the microfibrils [20, 24, 94]. 

Chabannes, M., Ruel, K., Yoshinaga, A., Chabbeit, B., Jauneau, A., Joseleau, J.P., Boudet, A.M. In situ analysis of lignins in transgenic tobacco reveals a differential impact of individual transformations on the spatial patterns of lignin deposition at the cellular and subcellular levels. Plant J 28, 271-282 (2001)... 

Figure 11.19 AFM images of lignin deposited on mica (a) LB film, (b) cast film. (Reproduced by permission of the American Chemical Society. Copyright 2002. Reprinted from Reference [71b]).

Vallet, C., Chabbert, B., Czaninski, Y., and Monties, B. 1996. Histochemistry of lignin deposition during scler-enchyma differentiation in alfaalfa stems. Ann. Bot., 78 625-632. 

The secondary cell wall contains about 94% cellulose and only grows when the primary cell wall is formed. In it, the cellulose molecules are highly oriented. With decreasing diameter, the following structural types can be distinguished fibers (0.06-0.28 mm), cell walls, macrofibrils (400 nm), microfibrils (20-30 nm), and elementary fibrils (3.5 nm). Lignin deposits as a cement in interfibrillar spaces of 5-10 nm in width. In fact, the inter-micellar spaces of 1 nm in width that occur between the elementary fibrils are accessible to H2O, ZnCl2, or I2, but not to dyestuffs. 

Due to the nonenzymatic nature of polymerization in lignin, the linkage pattern is irregular (Brett and Waldron, 1996). Lignin continues to form as long as there is space in the cell wall. It fills all spaces in the cell wall and replaces water (Brett and Waldron, 1996). The lignin deposition in the cell wall is well planned and controlled. It starts at different rates in different cell corners (Davin et al., 2009). The effect... 

---