Poster: Signaling, cell-to-cell
Abs #
428: Recessive-interfering mutations in the GA-response gene SLEEPY1 are rescued by overexpression of its homologue SNEEZY
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Presenter: |
Strader, Lucia C, lucia_strader@yahoo.com |
Authors | Strader, Lucia C (A) Ritchie, Sian (A) Steber, Camille M (B) (A) | | Affiliations: |
(A): Washington State University
(B): United States Department of Agriculture-Agriculture Research Services
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This study investigates the genetic interaction of two F-box genes, SLEEPY1 (SLY1) and SNEEZY (SNZ), in Arabidopsis thaliana GA (gibberellin) signaling. The SLY1 gene encodes an F-box subunit of an SCF E3 ubiquitin ligase complex that positively regulates GA signaling. The sly1-2 and sly1-10 mutants result in recessive GA-insensitive phenotypes including increased seed dormancy, dwarfism, reduced fertility, and overaccumulation of DELLA proteins including RGA, GAI and RGL2. The requirement for SLY1 in the GA-stimulated disappearance of DELLA proteins suggests that SCFSLY1 negatively regulates these negative regulators by targeting them for destruction via the ubiquitin-26S proteasome pathway. Overexpression of SLY1 in sly1-2 and sly1-10 plants rescues the recessive GA-insensitive phenotype of these mutants. Surprisingly, antisense expression of SLY1 also rescues the GA-insensitive phenotype of these mutants. This result caused us to hypothesize that the SLY1 homologue SNEEZY can functionally replace SLY1 in the absence of the recessive interfering sly1-2 and sly1-10 proteins. This hypothesis was supported by identification of SNZ as a gene that suppresses sly1-10 when overexpressed. In addition to rescuing the sly1-10 dwarf phenotype, SNZ overexpression also restored normal RGA protein levels, suggesting that the SNZ F-box protein can replace SLY1 in the GA-induced proteolysis of RGA. If the C-terminal truncation caused by sly1-2 and sly1-10 alleles interferes with SNZ rescue, overexpression of truncated sly1-2 may interfere with wild-type SLY1 function. Indeed, overexpression of sly1-2 in wild-type Ler (Landsberg erecta) yields dwarf plants. The predicted SNZ amino acid sequence is highly conserved among plants, indicating that it has a key function in these organisms.
