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- Desnos, T., et al.
(författare)
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Procuste1 mutants identify two distinct genetic pathways controlling hypocotyl cell elongation, respectively in dark and light-grown Arabidopsis seedlings
- 1996
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Ingår i: Development. - 0950-1991 .- 1477-9129. ; 122:2, s. 683-693
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Tidskriftsartikel (refereegranskat)abstract
- Plant morphogenesis is dependent on a tight control of cell division and expansion. Cell elongation during postembryonic hypocotyl growth is under the control of a light-regulated developmental switch. Light is generally believed to exert its effects on hypocotyl elongation through a phytochrome- and blue-light receptor- mediated inhibitory action on a so far unknown cell elongation mechanism. We describe here a new class of allelic mutants in Arabidopsis, at the locus PROCUSTE1 (prc1-1 to -4), which have a hypocotyl elongation defect specifically associated with the dark-grown developmental program. Normal hypocotyl elongation is restored in plants grown in white, blue or red light. In agreement with this, the constitutive photomorphogenic mutation cop1-6, which induces a deetiolated phenotype in the dark, is epistatic to prc1-2 for the hypocotyl phenotype. Epistasis analyses in red and blue light respectively, indicate that phytochrome B but not the blue light receptor HY4, is required for the switch from PRC1-dependent to PRC1-independent elongation. The conditional hypocotyl growth defect is associated with a deformation of the hypocotyl surface due to an uncontrolled swelling of epidermal, cortical or endodermal cells, suggesting a defect in the structure of the expanding cell wall, A similar phenotype was observed in elongating roots, which was however, independent of the light conditions. The aerial part of mature mutant plants grown in the light was indistinguishable from the wild type. prc1 mutants provide a means of distinguishing, for the first time, two genetic pathways regulating hypocotyl cell elongation respectively in dark- and light-grown seedlings, whereby light not only inhibits hypocotyl growth, but also activates a PRC1-independent cell elongation program.
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| 2. |
- Traas, J., et al.
(författare)
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Normal Differentiation Pattern in Plants Lacking Microtubular Preprophase Bands
- 1995
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 375:6533, s. 676-677
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Tidskriftsartikel (refereegranskat)abstract
- IT is generally accepted that polarized cell expansion and the strict control of division plane alignment are prerequisites for ordered spatial development in higher plants(1). This appears to be linked to the presence of cell walls, which immobilize the cells and fix their relative positions. In this context, the cortical cytoskeleton is thought to play a central role(1-6). Interphase microtubules are often aligned perpendicular to the growth axis and it has been proposed that they control cell expansion, probably in combination with the cell wall. Another cytoskeletal array, the prephophase band, has been associated with division plane alignment. This structure, which girdles the cell at the G2 phase of the cell cycle and at prophase, precisely predicts the future division site and probably fixes it. Here we describe different mutants in Arabidopsis that are unable to form these two cortical microtubular arrays. As expected, this defect is associated with irregular cell expansion and the inability to align division planes. Surprisingly, however, the mutations do not affect differentiation patterns: all cell types and organs are in their correct relative positions.
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