脱落酸代谢与信号传递及其调控种子休眠与萌发的分子机制
宋松泉1,4,刘军2,徐恒恒2,刘旭3(),黄荟4
ABA Metabolism and Signaling and Their Molecular Mechanism Regulating Seed Dormancy and Germination
SONG SongQuan1,4,LIU Jun2,XU HengHeng2,LIU Xu3(),HUANG Hui4

图3. ABA信号传递途径和DOG1调控种子休眠的新模型(根据NONOGAKI[19]修改)
在ABA感受和信号传递途径中(左),ABA受体(PYR/PYL/RCAR)与ABA不敏感1(ABI1)亚家族2C类蛋白磷酸酶(PP2C)包括ABI1、ABI2、ABA过敏感1(HAB1)和HAB2结合,并使PP2C失活,从而导致激酶例如蔗糖非发酵-1相关的蛋白激酶2(SnRK2)的去抑制和活化。这些激酶然后磷酸化和活化转录因子(TF),TF与靶启动子(Pro)结合,诱导下游的ABA反应基因。对于种子休眠的调节(右),DOG1与ABA过敏感萌发1(AHG1)和AHG3结合,PP2C主要在种子中起作用。DOG1被认为是通过束缚这些ABA信号传递的负调控因子和增加种子对ABA的敏感性而引起种子休眠

Fig. 3. ABA signalling pathway and emerging model of seed dormancy regulated by DOG1 (Modified from NONOGAKI [19])
In the ABA perception and signaling pathway (left), ABA receptors (PYR/PYL/RCARs) bind to and inactivate the ABA INSENSITIVE1 (ABI1) subfamily protein phosphatases 2C (PP2Cs), including ABI1, ABI2, HYPERSENSITIVE TO ABA1 (HAB1) and HAB2, which results in de-repression and activation of kinases, such as sucrose nonfermenting1-related protein kinase 2 (SnRK2). These kinases then phosphorylate and activate transcription factors (TF), which bind to the target promoters (Pro), to induce ABA-responsive genes downstream. For seed dormancy regulation (right), DOG1 binds to ABA HYPERSENSITIVE GERMINATION1 (AHG1) and AHG3, PP2Cs primarily functioning in seeds. The DOG1 is thought to cause seed dormancy by sequestrating these negative regulators of ABA signaling and increasing ABA sensitivity in seeds