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The E3 ubiquitin ligase SPL11 regulates both programmed cell death and flowering time in rice
| Title: | The E3 ubiquitin ligase SPL11 regulates both programmed cell death and flowering time in rice |
| Author: | Vega-Sanchez, Miguel E. |
| Description: | The rice E3 ubiquitin ligase SPL11 was previously characterized as a negative regulator of both programmed cell death (PCD) and broad-spectrum disease resistance, suggesting its putative role in the ubiquitination/protein degradation machinery, or other ubiquitin-mediated pathway. A novel role for SPL11 in flowering time control was identified via its interaction with SPIN1 (SPL11-interacting protein 1), a nuclear, RNA/DNA binding protein and STAR (signal transduction and activation of RNA) family member. In addition to ubiquitinating SPIN1 in vitro, SPL11 downregulated the expression of Spin1 during the light phase to promote flowering. Overexpression of Spin1 inhibited flowering in both short and long days and affected Spl11 expression as well. These results link ubiquitination and RNA metabolism in flowering time control. Isolation of spl11-mediated cell death suppressor mutants (sds) provided additional evidence that PCD is under genetic control in the spl11 mutant. The sds mutants showed various levels of cell death suppression, had wild-type levels of resistance to bacterial blight, and repressed the elevated defense gene expression of spl11. The delayed flowering phenotype of spl11 in long days was partially repressed in sds plants independently of cell death suppression levels, suggesting that the PCD and flowering pathways may partially overlap. Another RNA binding protein was identified in a yeast two-hybrid screen designed to isolate SPIN1-interacting partners. Rbs1 (RNA binding and SPIN1-interacting 1) was shown to promote cell death when overexpressed in both Nicotiana benthamiana and rice. Rbs1 was upregulated in lesion mimic-expressing leaves of spl11, suggesting that it may contribute to the cell death phenotype. RBS1 may constitute a link between the flowering and PCD pathways controlled by SPL11. The data presented here provides the first evidence of a link between cell death control and the switch to reproductive development in plants. |
| Permanent Link: |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1216996821
http://hdl.handle.net/2374.OX/107426 |
| Date: | 2008 |
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