Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Correnssstrasse 3, D-06466 Gatersleben, Germany.
J Plant Physiol. 2012 Mar 15;169(5):501-8. doi: 10.1016/j.jplph.2011.11.017. Epub 2012 Jan 5.
During the late stages of seed development, the embryo patterning program is completed and maturation is initiated. One of the main events during the maturation phase is the acquisition of dormancy, characterized by the failure of a normally developed seed to germinate precociously. Dormancy is controlled by a complex regulatory mechanism that involves the phytohormone gibberellin (GA) and the transcription factor FUSCA3 (FUS3). Here, we demonstrate the importance of the previously characterized GA regulator EFFECTOR OF TRANSCRIPTION2 (AtET2) for correct seed development. We show that entering the maturation phase, seeds of the et2-1 mutant, which contain a non-functional AtET2 gene, fail to induce dormancy. This correlates well with the observed activity pattern of the AtET2 promoter, which is active in the maturing embryo. AtET2 action during seed development is dependent on a complex interaction with GA and the FUS3 gene, the latter evidenced by the phenotypes of the et2-1 fus3-T double mutant. We show that in vitro expressed AtET2 protein can bind to both linear and supercoiled DNA without any obvious sequence preference. This suggests that, within a larger protein complex, AtET2 might be required for the correct positioning upon the DNA.
在种子发育的后期阶段，胚胎模式程序完成，并开始成熟。在成熟阶段的主要事件之一是获得休眠，其特征是正常发育的种子不能过早发芽。休眠受复杂的调控机制控制，该机制涉及植物激素赤霉素（GA）和转录因子 FUSCA3（FUS3）。在这里，我们证明了先前表征的 GA 调节剂 EFFECTOR OF TRANSCRIPTION2（AtET2）对正确种子发育的重要性。我们表明，进入成熟阶段，含有无功能 AtET2 基因的 et2-1 突变体种子未能诱导休眠。这与观察到的 AtET2 启动子的活性模式很好地相关，该启动子在成熟的胚胎中是活跃的。AtET2 在种子发育过程中的作用依赖于与 GA 和 FUS3 基因的复杂相互作用，后者由 et2-1 fus3-T 双突变体的表型证明。我们表明，体外表达的 AtET2 蛋白可以结合线性和超螺旋 DNA，而没有任何明显的序列偏好。这表明，在更大的蛋白质复合物中，AtET2 可能需要正确定位在 DNA 上。
