Mutant Name: irx1 (irregular xylem 1)
| Gene Name | CesA8 |
| Protein Name | cellulose synthase |
| Mutagen | EMS |
| Category | forward genetics |
| Organism | Arabidopsis thaliana |
| Ecotype | Lb |
| Donor | |
| General Description |
1. walls of mature xylem element appear to collapse inward, but the organization of the vascular tissue and the entire stem are fine. 2. grow normally and do not exhibit any apparent alterations in morphology except slightly smaller. 3. irx1-1 is caused by D683N resulted from G to A mutation; irx1-2 is caused by S679L from C to T muation. |
| Organ Specificity |
1. apart from in stems, collapsed xylem also observed in mature hypocotyls and primary root and petioles. 2. irx1 is expressed in the same tissue with irx3 and they interact with each other. |
| Impact on Wall |
1.stems are weaker, stiffness (bending modulus) is only 34% of wt at 48 days old plants. 2. for both bending modulus and maximum stress at yield, the differences between wt and irx1 became greater with increasing stem age. 3. no apparent qualitative alterations in the deposition of lignin or phenolics |
| Impact on Sugar Composition |
1. no difference o sugar composition of cell wall from stem. 2. at all stages of stem development, showed a large decrease in total cellulose content. |
| Reference |
1. Turner, S.R. and Somerville, C.R. (1997). Collapsed xylem phenotype of Arabidopsis identifies mutants deficient in cellulose deposition in hte secondary cell wall. Plant Cell. 9, 689-701. 2. Taylor, N.G., Laurie, S. and Turner, S.R. (2000). Multiple cellulose synthase catalytic subunites are required for cellulose synthesis in Arabidopsis. Plant Cell. 12, 2529-2539. |