Mutant Name: fra4
| Gene Name | RHD3 |
| Protein Name | GTP-binding protein (putative) |
| Mutagen | EMS |
| Category | forward genetics |
| Organism | Arabidopsis thaliana |
| Ecotype | Col |
| Donor | |
| General Description |
1.The fra4 mutants showed a dramatic reduction in the wall thickness of fibers, vessels, and pith cells in the inflorescence stems and, concomitantly, a decrease in the mechanical strength of stems.The reduced wall thickness in the fra4 mutant was accompanied by an alteration in cell wall composition. 2.A point mutation (G to A) of the RHD3 gene is responsible for the fra4 phenotypes. |
| Organ Specificity | 1.The RHD3 gene is expressed in all young elongating organs and exhibited a strong expression in developing fiber and xylem cells. |
| Impact on Wall |
1.The fra4 mutation causes a reduction in secondary wall thickening in fiber and vessel cells. Quantitative measurement from transmission electron micrographs showed that the average level of reduction in fiber wall thickness in the fra4 mutant was 55% compared with the wild type. 2. The reduced wall thickness in the fra4 mutant was accompanied by an alteration in cell wall composition. 3.The fra4 mutation also alters the organization of the actin cytoskeleton. |
| Impact on Sugar Composition |
1.The crystalline cellulose amount in the fra4 mutant was reduced to 82% of that of the wild type. 2.The total glucose in the cell walls of the fra4 mutant was reduced to 87% of that of the wild type. 3.Mutants did not appear to have any reduction in the amount of other cell wall sugars except for a slight change in mannose and fucose. |
| Reference | 1.Hu Y, Zhong R, Morrison WH 3rd, Ye ZH. The Arabidopsis RHD3 gene is required for cell wall biosynthesis and actin organization. Planta. 2003 Oct;217(6):912-21. |