Summary Strigolactones (SLs) and gibberellins (GAs) have been found to inhibit plant branching or tillering, but molecular mechanisms underlying the interplay between SL and GA signaling to modulate tillering remain elusive. We found that the transcription factor OsMADS23 plays a crucial role in the crosslink between SL and GA signaling in rice tillering. Loss‐of‐function mutant osmads23 shows normal axillary bud formation but defective bud outgrowth, thus reducing the tiller number in rice, whereas overexpression of OsMADS23 significantly increases tillering by promoting tiller bud outgrowth. OsMADS23 physically interacts with DELLA protein SLENDER RICE1 (SLR1), and the interaction reciprocally stabilizes each other. Genetic evidence showed that SLR1 is required for OsMADS23 to control rice tillering. OsMADS23 acts as an upstream transcriptional repressor to inhibit the expression of SL receptor gene DWARF14 (D14), and addition of SLR1 further enhances OsMADS23‐mediated transcriptional repression of D14, indicating that D14 is the downstream target gene of OsMADS23–SLR1 complex. Moreover, application of exogenous SL and GA reduces the protein stability of OsMADS23–SLR1 complex and promotes D14 expression. Our results revealed that SLs and GAs synergistically inhibit rice tillering by destabilizing OsMADS23–SLR1 complex, which provides important insights into the molecular networks of SL–GA synergistic interaction during rice tillering.

中文翻译：

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SLR1-OsMADS23-D14 模块介导独脚金内酯和赤霉素信号传导之间的串扰，以控制水稻分蘖


摘要 独脚金内酯 （SLs） 和赤霉素 （GAs） 已被发现可以抑制植物分枝或分蘖，但 SL 和 GA 信号传导之间相互作用以调节分蘖的分子机制仍然难以捉摸。我们发现转录因子 OsMADS23 在水稻分蘖中 SL 和 GA 信号之间的交联中起关键作用。功能丧失突变体 osmads23 显示腋芽形成正常，但芽生长缺陷，从而减少水稻中的分蘖数，而 OsMADS23 的过表达通过促进分蘖芽生长而显着增加分蘖。OsMADS23 与 DELLA 蛋白 SLENDER RICE1 （SLR1） 发生物理相互作用，并且相互作用相互稳定。遗传证据表明，OSMADS23 需要 SLR1 来控制水稻分蘖。OsMADS23 作为上游转录抑制因子抑制 SL 受体基因 DWARF14 （D14） 的表达，添加 SLR1 进一步增强 OsMADS23 介导的 D14 转录抑制，表明 D14 是 OsMADS23-SLR1 复合物的下游靶基因。此外，外源性 SL 和 GA 的应用降低了 OsMADS23-SLR1 复合物的蛋白质稳定性并促进了 D14 表达。我们的结果表明，SLs 和 GAs 通过破坏 OsMADS23-SLR1 复合物的稳定性协同抑制水稻分蘖，这为水稻分蘖过程中 SL-GA 协同相互作用的分子网络提供了重要的见解。