Article Abstract:
A subtilisin-like serine protease related to regulation of density of stomata, which control plant gas exchange with the atmosphere, and distribution of Arabidopsis thaliana is discussed. A. thaliana mutants with altered stomatal characteristics have been isolated and studied. SDD1 is proposed to act as a processing protease involved in the mediation of a signal controlling development of cell lineages that precede guard cell formation. The sdd1-1 mutant has a 2- to 4-fold increase of in stomata density and formation of clustered stomata, but the internal leaf architecture is not changed.
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Article Abstract:
An SCF ubiquitin-ligase complex required for auxin, that is indole-3-acetic acid (IAA), response in Arabidposis thaliana has been identtified. Auxin is a plant hormone that regulates various aspects of plant growth/development and mutations in AK1 (ital) or TIRI1 (ital) bring a decrease in auxin response. Overexpression of TIR1 enhances auxin response, which might indicate that SCF (super.TIR1) is a limiting factor. New support exists for a model in which auxin activity is dependent on the regulated proteolysis of repressor proteins.
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Article Abstract:
Key regulatory proteins need to be modified by ubiquitin or a related protein for appropriate auxin response in Arabidopsis. Experiments with Transport Inhibitor Response 1 (TIR1) mutants underlines the role of this gene for auxin-response. The mutants did not have several of the growth responses moderated by auxin. Sequence comparisons suggests links between this gene, the yeast protein Grr1p and the human protein SKP2.
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