Seed germination of GA-insensitive sleepy1 mutants does not require RGL2 protein disappearance in Arabidopsis
Seed germination of GA-insensitive sleepy1 mutants does not require RGL2 protein disappearance in Arabidopsis
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DOI：
10.1105/tpc.106.048009
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发表时间：
2007-03-01
期刊：
影响因子：
11.6
通讯作者：
Steber, Camille M.
中科院分区：
文献类型：
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作者：
Ariizumi, Tohru;Steber, Camille M.
我们探讨了赤霉素（GA）信号基因SLEEPY 1（SLY 1）和RGA-LIKE 2（RGL 2）在拟南芥种子萌发调控中的作用，拟南芥种子萌发需要激素GA。GA生物合成突变体ga 1 -3中的种子萌发失败被GA和DELLA基因RGL 2中的突变所拯救，这表明RGL 2抑制种子萌发。RGL 2蛋白在野生型种子萌发之前消失，这与GA通过引起SCFSLY 1 E3泛素连接酶复合物触发RGL 2的泛素化和破坏来刺激萌发的模型一致。与ga 1 -3不同，GA不敏感突变体sly 1表现出可变的种子休眠。种子休眠性高的种子批后熟缓慢，较强的等位基因需要更多的时间。我们预计，如果RGL 2负控制种子发芽，sly 1突变种子发芽良好，应积累较低的RGL 2水平比那些未能发芽。令人惊讶的是，RGL 2积累在高水平，甚至在后成熟的sly 1突变体种子与100%的发芽，这表明RGL 2的消失是不是一个先决条件的sly 1背景下的种子发芽。没有GA，几个GA诱导的基因显示增加积累sly 1种子相比，GA 1 -3。这是可能的RGL 2种子发芽的阻遏物被失活sly 1突变体种子后熟。
We explore the roles of gibberellin (GA) signaling genes SLEEPY1 (SLY1) and RGA-LIKE2 (RGL2) in regulation of seed germination in Arabidopsis thaliana, a plant in which the hormone GA is required for seed germination. Seed germination failure in the GA biosynthesis mutant ga1-3 is rescued by GA and by mutations in the DELLA gene RGL2, suggesting that RGL2 represses seed germination. RGL2 protein disappears before wild-type seed germination, consistent with the model that GA stimulates germination by causing the SCFSLY1 E3 ubiquitin ligase complex to trigger ubiquitination and destruction of RGL2. Unlike ga1-3, the GA-insensitive sly1 mutants show variable seed dormancy. Seed lots with high seed dormancy after-ripened slowly, with stronger alleles requiring more time. We expected that if RGL2 negatively controls seed germination, sly1 mutant seeds that germinate well should accumulate lower RGL2 levels than those failing to germinate. Surprisingly, RGL2 accumulated at high levels even in after-ripened sly1 mutant seeds with 100% germination, suggesting that RGL2 disappearance is not a prerequisite for seed germination in the sly1 background. Without GA, several GA-induced genes show increased accumulation in sly1 seeds compared with ga1-3. It is possible that the RGL2 repressor of seed germination is inactivated by after-ripening of sly1 mutant seeds.