Mutant Name: irx3 (irregular xylem 3)
| Gene Name | CesA7 |
| Protein Name | cellulose synthase |
| Mutagen | EMS |
| Category | forward genetics |
| Organism | Arabidopsis thaliana |
| Ecotype | Lb |
| Donor | |
| General Description |
1.Mutants have greatly reduced cellulose content in secondary cell walls; 2. the walls of the mature xylem elements in stems appear to collapse inward, but the organization of both the vascular tissue and the entire stem are identical to that of WT; 3. grow normally and do not exhibit any readily apparent alterations in morphology except slightly smaller; 4. stems are less rigid than WT and weaker, stiffness (bending modulus) is only 10% of WT at 48 days old, and the difference of stiffness increase along with aging; 5. irx3 and irx1 are expressed in the same tissues and interact with each other; 6. mutation caused by a Trp859 to stop codon change resulted from a G to A transition, resulting a protein lacking 168 C-terminal amino acids. |
| Organ Specificity | Mutants show a large decrease in total cellulose content of the stem during all stages of stem development, and no difference in leaves. |
| Impact on Wall | Mutant walls show different domains by stainning, and cell wall deposition has a very uneven pattern. |
| Impact on Sugar Composition |
1. no apparent qualitative alterations in the deposition of lignin or phenolics; 2. no difference on sugar composition of cell walls from stem. |
| Reference |
1. Taylor, N.G., Scheible, W., Cutler, S., Somerville, C.R., and Turner, S.R. (1999). The irregular xylem3 locus of Arabidopsis encodes a cellulose synthase required for secondary cell wall synthesis. Plant Cell 11, 769-779; 2. Turner, S.R., and Somerville, C.R. (1997). Collapsed xylem phenotype of Arabidopsis identifies mutants deficient in cellulose deposition in the secondary cell wall. Plant Cell 9, 689-701. |