| Autor: |
Howles PA; Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 2601, Australia., Birch RJ, Collings DA, Gebbie LK, Hurley UA, Hocart CH, Arioli T, Williamson RE |
| Jazyk: |
angličtina |
| Zdroj: |
The Plant journal : for cell and molecular biology [Plant J] 2006 Nov; Vol. 48 (4), pp. 606-18. Date of Electronic Publication: 2006 Oct 19. |
| DOI: |
10.1111/j.1365-313X.2006.02902.x |
| Abstrakt: |
The Arabidopsis radial swelling mutant rsw10 showed ballooning of root trichoblasts, a lower than wild-type level of cellulose and altered levels of some monosaccharides in non-cellulosic polysaccharides. Map-based cloning showed that the mutated gene (At1g71100) encodes a ribose 5-phosphate isomerase (RPI) and that the rsw10 mutation replaces a conserved glutamic acid residue with lysine. Although RPI is intimately involved with many biochemical pathways, media supplementation experiments suggest that the visible phenotype results from a defect in the production of pyrimidine-based sugar-nucleotide compounds, most likely uridine 5'-diphosphate-glucose, the presumed substrate of cellulose synthase. Two of three RPI sequences in the nuclear genome are cytoplasmic, while the third has a putative chloroplast transit sequence. The sequence encoding both cytoplasmic enzymes could complement the mutation when expressed behind the CaMV 35S promoter, while fusion of the RSW10 promoter region to the GUS reporter gene established that the gene is expressed in many aerial tissues as well as the roots. The prominence of the rsw10 phenotype in roots probably reflects RSW10 being the only cytosolic RPI in this tissue and the gene encoding the plastid RPI being relatively weakly expressed. We could not, however, detect a decrease in total RPI activity in root extracts. The rsw10 phenotype is prominent near the root tip where cells undergo division, endoreduplication and cell expansion and so are susceptible to a restriction in de novo pyrimidine production. The two cytosolic RPIs probably arose in an ancient duplication event, their present expression patterns representing subfunctionalization of the expression of the original ancestral gene. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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