低磷和低pH是酸性土壤限制作物生长的重要原因。我们前期发现低磷和低pH调控了大豆GmALMT1的表达，暗示大豆根系对低磷和低pH的响应存在共同调控途径。我们克隆了参与调控GmALMT1表达的GmSTOP1-3基因。该基因的超量表达能够恢复拟南芥stop1突变体对低pH的耐性，说明GmSTOP1-3调控了大豆对低pH胁迫的适应性。另外，GmSTOP1-3的表达受低磷上调，且其超量表达促进了低磷条件下转基因株系根系的生长。这些结果表明，GmSTOP1-3可能是大豆根系磷信号网络中一个新的调控因子。本项目拟通过对GmSTOP1-3超量或抑制表达转基因大豆材料根系生长和磷吸收的分析，结合分析其下游基因的表达模式以及互作蛋白的鉴定等，阐明GmSTOP1-3控制大豆根系生长的功能，建立以GmSTOP1-3为核心的大豆根系响应低磷胁迫的调控途径，为培育协同适应低磷和低pH胁迫的大豆品种奠定理论基础。

Phosphorus (P) deficiency and low pH are major limiting factors for crop production on acid soils. Our previous results showed that the expression of GmALMT1 was regulated by both of P deficiency and low pH, indicating that a common signaling pathway might present in plant response to both stresses. Furthermore, we found that a transcriptional factor, GmSTOP1-3, was involved in the regulation of GmALMT1 expression. Overexpressing GmSTOP1-3 could restore the acid tolerance of stop1 mutant, indicating the functions of GmSTOP1-3 in soybean low pH tolerance. Moreover, the expression of GmSTOP1-3 was enhanced by P deficiency. Overexpressing GmSTOP1-3 led to enhanced plants root growth under low P condition. The results indicated that GmSTOP1-3 might be a novel regulator in the P signaling network. In this project, we will further study root growth and P content of the transgenic soybean plants or hairy roots with overexpressing or suppressing GmSTOP1-3. Subsequently, the RNA-seq will be conducted to examine the global gene expression regulated by GmSTOP1-3. In addition, the proteins interacted with GmSTOP1-3 will be isolated by Co-IP and characterized. The results of this project will build a new P signaling pathway including GmSTOP1-3 as the main regulator, and thus provide useful theoretical foundation for developing soybean varieties, which coordinately and well adapt to both P deficiency and low pH on acid soils.