Arabidopsis cell wall, cellulose synthesis

Arabidopsis, cell wall, cellulose, cellulose synthesis, irregular xylem, mutant. 

Taylor N.G., Gardiner J.C., Whiteman R., and Turner S.R. (2004). Cellulose synthesis in the Arabidopsis secondary cell wall. Cellulose 11 329-338. 

One strategy to the enhance CO2 fixation in woody plants is to enhance the expression of genes required for cellulose deposition, which should enhance plant growth either by cell wall or just cellulose deposition. We have already isolated the full length of cDNAs for three kinds of cellulases, XET and expansin as plant cell growth regulators, and for two kinds of cellulose synthases and suCTOse synthase as a system of cellulose synthesis, as summarized in Table 2. If cellulose deposition is increased by the increased activity of each enzyme in the transformants of Arabidopsis, the gene can be introduced to woody plants to determine the cellulose deposition. 

T. Desprez, M. Jmaniec, E. F. Crowell, H. Jouy, Z. Pochylova, F. Parcy, H. Hofte, M. Gonneau, and S. Vemhettes, Organization of cellulose synthase complexes involved in the primary cell wall synthesis in Arabidopsis thaliana, Proc. Natl. Acad. Sci. U.S.A., 104 (2007) 15572-15577. 

TAYLOR, N.G., SCHEIBLE, W.R., CUTLER, S., SOMERVILLE, C.R., TURNER, S.R., The irregular xylem3 locus of Arabidopsis encodes a cellulose synthase required for secondary cell wall synthesis. Plant Cell, 1999,11,769-779. 

CELLULOSE SYNTHESIS IN THE ARABIDOPSIS SECONDARY CELL WALL... 

Cellulose Synthesis in Arabidopsis Secondary Cell Wall... 

In order for information gained from studying Arabidopsis to be of use to industry it is important to establish that mechanisms of cellulose synthesis are conserved between Arabidopsis and commercially important species such as crop plants and trees. Studies on CesA genes in rice represent a powerful example of how well the mechanism of cellulose synthesis is conserved between diverse species. Three brittle-culm mutants of rice are the result of mutations in the rice orthologues of AtCesA4, 7 and 8 (Tanaka et al. 2003). This result suggests that in secondary cell walls a very similar mechanism of both cellulose synthesis and rosette organization is conserved between rice and Arabidopsis. 

Studies on mutants affecting cellulose synthesis in the primary cell wall have also led to the idea that three catalytic subunits are required for cellulose synthesis in these cell types. These genes are different from those required in the secondary cell wall (Arioli et al. 1998 Fagard et al. 2000 Scheible et al. 2001). Work on the rswl mutant of Arabidopsis demonstrates that in addition to their catalytic fimc-tion, CesA proteins are also essential for determining rosette structure, rswl-1 is caused by a comparatively small amino acid change (Ala to Val) in AtCesAl, yet at the restrictive temperature the hexameric rosettes are replaced by smaller structures (Arioli et al. 1998). 

Some of the cell wall mutants, such as the mur mutants in Arabidopsis, affect dovmstream enzymes, which supply substrates for the glycosyl transferases involved in cell wall synthesis (Williamson et al. 2002). These types of mutations usually lead to a significant overall reduction in the rate of cellulose synthesis. Sucrose synthase (SuSy) (FC2.4.1.13) catalyzes the reversible conversion of sucrose and UDP to UDP-glucose and fructose thereby channeling sucrose into numerous pathways, including cell wall and starch biosynthesis. 

Sato S., Bfato T, Bfakegawa K., Ishii T, Liu Y.-G., Awano T, Takabe K., Nishiyama Y, Kuga T, Sato S., Nakamura Y, Tabata T, and Shibata D. 2001. Role of the putative membrane-bound endo-l,4-P-glucanase KORRIGAN in cell wall elongation and cellulose synthesis in Arabidopsis thaliana. Plant Cell Physiol 42 251-263. 

Desprez, T. et al. (2007) Organization of cellulose synthase complexes involved in primary cell wall synthesis in Arabidopsis thaliana. Proc. Natl Acad. Sci USA 104, 15572-15577... 

---