盐胁迫下，植物内积累的过量ROS影响细胞生理功能。类黄酮在维持ROS平衡方面扮演着重要角色，但其作用机制尚不明确。我们研究发现，类黄酮合成途径的GmbHLH130与GmCHI4可以提升大豆耐盐能力。由于GmbHLH130可特异地结合于GmCHI4基因启动子的G-box，我们推测GmCHI4是GmbHLH130的靶基因。有意思的是，盐胁迫不会显著改变GmbHLH130蛋白的含量，仅提升其Ser208磷酸化(S208p)水平，可见，S208p对GmbHLH130发挥耐盐调控功能有重要意义。本项目将研究：(1)GmbHLH130-S208p对GmCHI4的转录调控机制；(2)GmbHLH130-S208p通过GmCHI4的表达调控影响大豆的耐盐反应；(3)GmbHLH130-S208p与GmCHI4通过对类黄酮合成的调节提升大豆耐ROS次级危害的机制。本研究的开展可为改善作物耐盐性提供理论依据。

The excess ROS (Reactive oxygen species) accumulated in salinity conditions could damage the physiological functions of plant cells. It is reported that flavonoids play significant roles in eliminating the excess ROS, but the mechanistic detail by which the flavonoids fight against oxidative stress is still far from clear. Recently, we demonstrated that the salt tolerance of soybean root could be enhanced both by the GmbHLH130 and GmCHI4, which are two key components in the flavonoid synthesis pathway. Using the ChIP (Chromatin immuno-precipitation) and EMSA (Electrophoretic mobility shift assay) approaches, we previously found that the transcription factor GmbHLH130 bound directly to the G-box (5′-CACGTG-3′) motif in the promoter of GmCHI4 gene. Hence, it is believed that the GmCHI4 gene would be a direct downstream target of the GmbHLH130. However, there was no significant difference been found in protein level of the GmbHLH130 in response to salt stress. Interestingly, the phosphorylation of Ser208 (S208p) in the GmbHLH130 protein was up-regulated by salt stress, indicated that S208p played a significant role in regulating the functions of GmbHLH130 in response to salinity. In this project, we plan: (1) to study how GmbHLH130-S208p regulates the transcriptional expression of the GmCHI4 gene, and (2) to explore their functions in mediating soybean’s responses to salinity, also (3) to reveal the molecular mechanism of how flavonoids been ingeniously synthesized to enhance soybean’s tolerance to oxidative stress via the GmbHLH130-S208p and GmCHI4 in salinity conditions. These results will provide useful knowledge base for improving salt resistance of crops.