The Dof protein DAG1 mediates PIL5 activity on seed germination by negatively regulating GA biosynthetic gene AtGA3ox1
The Dof protein DAG1 mediates PIL5 activity on seed germination by negatively regulating GA biosynthetic gene AtGA3ox1
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DOI：
10.1111/j.1365-313x.2009.04055.x
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发表时间：
2010-01-01
期刊：
影响因子：
7.2
通讯作者：
Vittorioso, Paola
中科院分区：
文献类型：
--
作者：
Gabriele, Stefano;Rizza, Annalisa;Vittorioso, Paola
我们以前已经证明，编码拟南芥转录因子DOF影响萌发1（DAG 1）的基因的失活使种子萌发对光敏色素B（phyB）和赤霉素（GA）更敏感。dag1突变体种子需要比WT更少的红（R）光通量和更低的GA浓度来萌发。在这里，我们表明，基因光敏色素相互作用因子3样5（PIL 5）的失活导致下调DAG1。在dag1突变体背景中PIL 5的失活进一步增加了dag1突变体种子的发芽潜力，支持DAG1在PIL 5的阳性控制下的建议。dag1phyB种子的发芽表现出减少赤霉素的需求相比，phyB突变体种子，无论是在存在和不存在GA生物合成。此外，GA生物合成基因AtGA3ox1是上调dag1种子相比，野生型，和DAG1实际上结合到AtGA3ox1启动子，如染色质免疫沉淀实验所示。不同时间点的表达分析证实AtGA 3ox 1直接受DAG1调控，同时表明DAG1不是PIL 5的直接调控靶点。我们的数据表明，在phyB途径导致种子萌发，DAG1负调控GA的生物合成，并建议DAG1的PIL 5的下游行为。此外，分析的下胚轴的dag1和phyB突变体的小植株，过表达phyB的dag1突变体，以及dag1phyB双突变体的小植株表明，DAG1可能作为一个负调控元件下游的phyB也在下胚轴伸长。
P>We have previously shown that inactivation of the gene encoding the Arabidopsis thaliana transcription factor DOF AFFECTING GERMINATION 1 (DAG1) renders seed germination more sensitive to both phytochrome B (phyB) and gibberellins (GA). dag1 mutant seeds require less red (R) light fluence and a lower GA concentration than WT to germinate. Here, we show that inactivation of the gene PHYTOCHROME INTERACTING FACTOR 3-LIKE 5 (PIL5) results in down-regulation of DAG1. Inactivation of PIL5 in the dag1 mutant background further increased the germination potential of dag1 mutant seeds, supporting the suggestion that DAG1 is under the positive control of PIL5. Germination of dag1phyB seeds showed a reduced requirement of gibberellins as compared with phyB mutant seeds, both in the presence and in the absence of GA biosynthesis. Furthermore, the GA biosynthetic gene AtGA3ox1 is upregulated in dag1 seeds as compared with the WT, and DAG1 actually binds to the AtGA3ox1 promoter, as shown by chromatin immunoprecipitation experiments. Expression analysis at different time points confirms that AtGA3ox1 is directly regulated by DAG1, while suggesting that DAG1 is not a direct regulatory target of PIL5. Our data indicate that in the phyB pathway leading to seed germination, DAG1 negatively regulates GA biosynthesis and suggest that DAG1 acts downstream of PIL5. In addition, the analysis of hypocotyls of dag1 and phyB mutant plantlets, of plantlets overexpressing phyB in the dag1 mutant, as well as of dag1phyB double mutant suggests that DAG1 may act as a negative regulatory element downstream of phyB also in hypocotyl elongation.