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Rice APC/C(TE) controls tillering by mediating the degradation of MONOCULM 1.

Lin Q, Wang D, Dong H, Gu S, Cheng Z, Gong J, Qin R, Jiang L, Li G, Wang JL, Wu F, Guo X, Zhang X, Lei C, Wang H, Wan J - Nat Commun (2012)

Bottom Line: We demonstrate that TE encodes a rice homologue of Cdh1, and that TE acts as an activator of the anaphase promoting complex/cyclosome (APC/C) complex.We show that TE coexpresses with MOC1 in the axil of leaves, where the APC/C(TE) complex mediates the degradation of MOC1 by the ubiquitin-26S proteasome pathway, and consequently downregulates the expression of the meristem identity gene Oryza sativa homeobox 1, thus repressing axillary meristem initiation and formation.We conclude that besides having a conserved role in regulating cell cycle, APC/C(TE) has a unique function in regulating the plant-specific postembryonic shoot branching and tillering, which are major determinants of plant architecture and grain yield.

View Article: PubMed Central - PubMed

Affiliation: National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.

ABSTRACT
Rice MONOCULM 1 (MOC1) and its orthologues LS/LAS (lateral suppressor in tomato and Arabidopsis) are key promoting factors of shoot branching and tillering in higher plants. However, the molecular mechanisms regulating MOC1/LS/LAS have remained elusive. Here we show that the rice tiller enhancer (te) mutant displays a drastically increased tiller number. We demonstrate that TE encodes a rice homologue of Cdh1, and that TE acts as an activator of the anaphase promoting complex/cyclosome (APC/C) complex. We show that TE coexpresses with MOC1 in the axil of leaves, where the APC/C(TE) complex mediates the degradation of MOC1 by the ubiquitin-26S proteasome pathway, and consequently downregulates the expression of the meristem identity gene Oryza sativa homeobox 1, thus repressing axillary meristem initiation and formation. We conclude that besides having a conserved role in regulating cell cycle, APC/C(TE) has a unique function in regulating the plant-specific postembryonic shoot branching and tillering, which are major determinants of plant architecture and grain yield.

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TE physically interacts with MOC1 and OsCDC27.(a) Yeast two-hybrid assay showing that TE interacts with MOC1 and OsCDC27, but not with MOC1d and MOC1-m. The protein structure of MOC1 and MOC1d and the amino-acid substitutions in MOC1-m are shown on the right. (b) In vitro pull-down assay showing that MBP–TE, but not MBP itself, pulled down MOC1 (upper image) and OsCDC27 (middle image) from plant extracts. Coomassie blue staining (CBB) showing that roughly equal amounts of purified MBP-TE and MBP proteins were used in the pull-down assay (lower image). (c) BiFC assay showing that TE can interact with MOC1 and OsCDC27 in the nuclei of leaf cells of N. benthamiana. The signals of eYFP were not detected in the corresponding negative controls. White arrowheads indicate the nuclear membrane. Scale bar, 20 μm.
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f4: TE physically interacts with MOC1 and OsCDC27.(a) Yeast two-hybrid assay showing that TE interacts with MOC1 and OsCDC27, but not with MOC1d and MOC1-m. The protein structure of MOC1 and MOC1d and the amino-acid substitutions in MOC1-m are shown on the right. (b) In vitro pull-down assay showing that MBP–TE, but not MBP itself, pulled down MOC1 (upper image) and OsCDC27 (middle image) from plant extracts. Coomassie blue staining (CBB) showing that roughly equal amounts of purified MBP-TE and MBP proteins were used in the pull-down assay (lower image). (c) BiFC assay showing that TE can interact with MOC1 and OsCDC27 in the nuclei of leaf cells of N. benthamiana. The signals of eYFP were not detected in the corresponding negative controls. White arrowheads indicate the nuclear membrane. Scale bar, 20 μm.

Mentions: It has been reported previously that Cdh1 mainly recognizes the D-box (RxxLxxxxN/D/E) and KEN-box in the amino-terminal region of its substrates to target them for ubiquitination and degradation by the 26S proteasome17. The enhanced tillering phenotype in the loss-of-function te mutant suggests that TE could participate in targeted degradation of a positive regulator(s) of tillering. Through extensive analysis of known positive regulators of tillering and branching, we identified a typical D-box in the N-terminal region of the MOC1/LS/LAS protein (Supplementary Fig. S3a). Previous studies have reported a loss-of-function moc1 mutant that has dramatically reduced tiller number, whereas MOC1-overexpressing lines have increased tiller number17. Thus, we tested whether TE physically interacts with MOC1. A yeast two-hybrid assay showed that TE interacted with MOC1, but not with MOC1-d (deletion of 107 amino acids in the N-terminal region) or MOC1-m (in which the typical D-box was mutated) (Fig. 4a). In addition, an in vitro pull-down assay showed that MBP–TE protein but not the MBP control pulled down MOC1 protein from the total protein extracts of WT rice plants (Fig. 4b). Moreover, biomolecular fluorescence complementation (BiFC) assay showed that TE interacted with MOC1 in Nicotianabenthamiana leaf cells (Fig. 4c). These results suggest that TE directly interacts with MOC1 and that the D-box in the N-terminal region of MOC1 is required for its physical interaction with TE.


Rice APC/C(TE) controls tillering by mediating the degradation of MONOCULM 1.

Lin Q, Wang D, Dong H, Gu S, Cheng Z, Gong J, Qin R, Jiang L, Li G, Wang JL, Wu F, Guo X, Zhang X, Lei C, Wang H, Wan J - Nat Commun (2012)

TE physically interacts with MOC1 and OsCDC27.(a) Yeast two-hybrid assay showing that TE interacts with MOC1 and OsCDC27, but not with MOC1d and MOC1-m. The protein structure of MOC1 and MOC1d and the amino-acid substitutions in MOC1-m are shown on the right. (b) In vitro pull-down assay showing that MBP–TE, but not MBP itself, pulled down MOC1 (upper image) and OsCDC27 (middle image) from plant extracts. Coomassie blue staining (CBB) showing that roughly equal amounts of purified MBP-TE and MBP proteins were used in the pull-down assay (lower image). (c) BiFC assay showing that TE can interact with MOC1 and OsCDC27 in the nuclei of leaf cells of N. benthamiana. The signals of eYFP were not detected in the corresponding negative controls. White arrowheads indicate the nuclear membrane. Scale bar, 20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3316886&req=5

f4: TE physically interacts with MOC1 and OsCDC27.(a) Yeast two-hybrid assay showing that TE interacts with MOC1 and OsCDC27, but not with MOC1d and MOC1-m. The protein structure of MOC1 and MOC1d and the amino-acid substitutions in MOC1-m are shown on the right. (b) In vitro pull-down assay showing that MBP–TE, but not MBP itself, pulled down MOC1 (upper image) and OsCDC27 (middle image) from plant extracts. Coomassie blue staining (CBB) showing that roughly equal amounts of purified MBP-TE and MBP proteins were used in the pull-down assay (lower image). (c) BiFC assay showing that TE can interact with MOC1 and OsCDC27 in the nuclei of leaf cells of N. benthamiana. The signals of eYFP were not detected in the corresponding negative controls. White arrowheads indicate the nuclear membrane. Scale bar, 20 μm.
Mentions: It has been reported previously that Cdh1 mainly recognizes the D-box (RxxLxxxxN/D/E) and KEN-box in the amino-terminal region of its substrates to target them for ubiquitination and degradation by the 26S proteasome17. The enhanced tillering phenotype in the loss-of-function te mutant suggests that TE could participate in targeted degradation of a positive regulator(s) of tillering. Through extensive analysis of known positive regulators of tillering and branching, we identified a typical D-box in the N-terminal region of the MOC1/LS/LAS protein (Supplementary Fig. S3a). Previous studies have reported a loss-of-function moc1 mutant that has dramatically reduced tiller number, whereas MOC1-overexpressing lines have increased tiller number17. Thus, we tested whether TE physically interacts with MOC1. A yeast two-hybrid assay showed that TE interacted with MOC1, but not with MOC1-d (deletion of 107 amino acids in the N-terminal region) or MOC1-m (in which the typical D-box was mutated) (Fig. 4a). In addition, an in vitro pull-down assay showed that MBP–TE protein but not the MBP control pulled down MOC1 protein from the total protein extracts of WT rice plants (Fig. 4b). Moreover, biomolecular fluorescence complementation (BiFC) assay showed that TE interacted with MOC1 in Nicotianabenthamiana leaf cells (Fig. 4c). These results suggest that TE directly interacts with MOC1 and that the D-box in the N-terminal region of MOC1 is required for its physical interaction with TE.

Bottom Line: We demonstrate that TE encodes a rice homologue of Cdh1, and that TE acts as an activator of the anaphase promoting complex/cyclosome (APC/C) complex.We show that TE coexpresses with MOC1 in the axil of leaves, where the APC/C(TE) complex mediates the degradation of MOC1 by the ubiquitin-26S proteasome pathway, and consequently downregulates the expression of the meristem identity gene Oryza sativa homeobox 1, thus repressing axillary meristem initiation and formation.We conclude that besides having a conserved role in regulating cell cycle, APC/C(TE) has a unique function in regulating the plant-specific postembryonic shoot branching and tillering, which are major determinants of plant architecture and grain yield.

View Article: PubMed Central - PubMed

Affiliation: National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.

ABSTRACT
Rice MONOCULM 1 (MOC1) and its orthologues LS/LAS (lateral suppressor in tomato and Arabidopsis) are key promoting factors of shoot branching and tillering in higher plants. However, the molecular mechanisms regulating MOC1/LS/LAS have remained elusive. Here we show that the rice tiller enhancer (te) mutant displays a drastically increased tiller number. We demonstrate that TE encodes a rice homologue of Cdh1, and that TE acts as an activator of the anaphase promoting complex/cyclosome (APC/C) complex. We show that TE coexpresses with MOC1 in the axil of leaves, where the APC/C(TE) complex mediates the degradation of MOC1 by the ubiquitin-26S proteasome pathway, and consequently downregulates the expression of the meristem identity gene Oryza sativa homeobox 1, thus repressing axillary meristem initiation and formation. We conclude that besides having a conserved role in regulating cell cycle, APC/C(TE) has a unique function in regulating the plant-specific postembryonic shoot branching and tillering, which are major determinants of plant architecture and grain yield.

Show MeSH