Mutant Name: rhd1(root hair defective1)
| Gene Name | RHD1 |
| Protein Name | UDP-glucose 4-epimerase |
| Mutagen | EMS |
| Category | forward genetics |
| Organism | Arabidopsis thaliana |
| Ecotype | Col |
| Donor | |
| General Description |
1. rhd1 mutant has dramatic bulging of root epidermal cells because of a deficiency of D-galactose in specific cell wall polymers. 2. rhd1 can be rescued by addition of D-Galactose. 3. Ethylene specifically suppresses the rhd1 phenotype and modulates the channeling of UDP-D-Gal into cell wall polymers. 4.The nucleotide substitutions in rhd1-1, -2, -3, and -4 mutant alleles were 1260G/A, 1833C/T, 436G/A, and 1023G/A and gave rise to the amino acid substitutions 186Gly/Glu, 250Ala/Val, 63Asp/Asn, and 135Trp/Stop, respectively. |
| Organ Specificity | 1. RHD1 is ubiquitously expressed. rhd1 can be rescued by addition of D-Galactose. |
| Impact on Wall | |
| Impact on Sugar Composition |
1. Epidermal cell walls in the root expansion zone lack arabinosylated (1-6)-beta-D-galactan and galactosylated XG. 2. In cortical cells of rhd1, galactosylated XG is absent, but an arabinosylated (1-6)-beta-D-galactan is present. 3. rhd1 is partially deficient in cell wall arabinogalactan-protein. |
| Reference |
1. Schiefelbein, J.W., and Somerville, C. (1990). Genetic Control of Root Hair Development in Arabidopsis thaliana. Plant Cell 2, 235-243. 2. Seifert, G.J., Barber, C., Wells, B., Dolan, L., and Roberts, K. (2002). Galactose biosynthesis in Arabidopsis: Genetic evidence for substrate channeling from UDP-D-galactose into cell wall polymers. Curr. Biol. 12, 1840-1845. 3. Seifert GJ, Barber C, Wells B, Roberts K. Growth regulators and the control of nucleotide sugar flux. Plant Cell. 2004 Mar;16(3):723-30. |