The semi-determinate stem growth habit in leguminous crops, similar to the “green revolution” semi-dwarf trait in cereals, is a key plant architecture trait that affects several other traits determining grain yield. In soybean semi-determinacy is modulated by a post-domestication gain-of-function mutation in the gene, Dt2, which encodes an MADS-box transcription factor. However, its role in systemic modification of stem growth and other traits is unknown. In this study, we show that Dt2 functions not only as a direct repressor of Dt1, which prevents terminal flowering, but also as a direct activator of putative floral integrator/identity genes including GmSOC1, GmAP1, and GmFUL, which likely promote flowering. We also demonstrate that Dt2 functions as a direct repressor of the putative drought-responsive transcription factor gene GmDREB1D, and as a direct activator of GmSPCH and GmGRP7, which are potentially associated with asymmetric division of young epidermal cells and stomatal opening, respectively, and may affect the plant's water-use efficiency (WUE). Intriguingly, Dt2 was found to be a direct activator or repressor of the precursors of eight microRNAs targeting genes potentially associated with meristem maintenance, flowering time, stomatal density, WUE, and/or stress responses. This study thus reveals the molecular basis of pleiotropy associated with plant productivity, adaptability, and environmental resilience.

豆科作物的半决定性茎生长习性，类似于谷物中的“绿色革命”半矮化性状，是一个关键的植物结构性状，影响着决定谷物产量的其他几个性状。在大豆中，半决定性是通过基因Dt2中的驯化后功能获得性突变来调节的，该基因编码 MADS-box 转录因子。然而，它在茎生长和其他性状的系统改变中的作用尚不清楚。在这项研究中，我们表明 Dt2 不仅可以作为Dt1的直接阻遏物（阻止终末开花），而且可以作为假定的花整合/识别基因（包括GmSOC1 、 GmAP1和GmFUL ）的直接激活剂（可能促进开花）。我们还证明，Dt2 可以作为假定的干旱反应转录因子基因GmDREB1D的直接抑制子，以及GmSPCH和GmGRP7的直接激活子，它们分别与年轻表皮细胞的不对称分裂和气孔开放有关，并且可能影响工厂的水分利用效率（WUE）。有趣的是，Dt2被发现是八种microRNA前体的直接激活剂或阻遏剂，其目标基因可能与分生组织维持、开花时间、气孔密度、WUE和/或应激反应相关。因此，这项研究揭示了与植物生产力、适应性和环境恢复力相关的多效性的分子基础。