独脚金内酯提高水稻磷素吸收利用的新机制

Due to low phosphate (P) concentration in soil in many Chinese regions, it is essential to elucidate the potential to uptake and to utilize P for plant adaptation to P-deficient condition. Strigolactones, novel plant hormones, are proved to play important roles to help plants efficiently uptake and utilize P through actions such as modifying root growth in response to P deficiency. Recently, we found that strigolactones improved P uptake and translocation from the shoot to root when plant supplementing low P. However, the mechanisms of strigolactone-induced P uptake and translocation remain poorly understood. It has been well reported that P transporters require the coordination of a set of proteins with P transport activities. Based on relative clear regulation of genes encoding OsPT1s, six stigolactones’ synthetic and signaling mutants and ample transgenic plants regarding regulating gene encoding OsPT1s are used in this project. Phosphate uptake and translocation from the root to shoot are analyzed through pharchemical and 32P-labled methods; The RNA and protein level of P transporters in rice are observed by qRT-PCR and western bloting methods, which will help to understand how strigolactones regulate P transporters through transcriptional and/or from post-translational mechanisms. We analyze whether strigolactone regulate OsPT1s is involved in the central regulators of P starvation signaling, transcription factor OsPHR2. And cellular trafficking mechanism regulating OsPT1s is analyzed through recording the degradation of the kinase subunit CK2β3 and complementary high-affinity phosphate protein OsPHF1. The different fragments of OsPT1;8 promoter fused to the GUS reporter and yeast one-hybrid system are used to analyze the possible mechanism about strigolactone inducing the expression of OsPT1s.

充分挖掘作物高效吸收利用磷的生物学潜力，对于养分资源高效利用具有重要意义。独脚金内酯(SL)作为新发现的植物激素，已经被证实在低磷条件下可通过调控根系生长等途径提高植物对磷的吸收利用。我们发现，低磷条件下SL直接促进了水稻对磷的吸收转运，但其中涉及的机制还不清楚。由于调控水稻磷转运体基因的信号网络已日益完善，本课题充分利用丰富的磷转运体调控网络的转基因材料和SL合成及信号突变体，通过药理学和32P同位素标记方法研究SL对水稻磷吸收转运的影响；利用qRT-PCR和免疫印迹方法检测磷转运体RNA和蛋白水平，在此基础上分析以转录因子OsPHR2为中心的转录调控网络基因和蛋白激酶CK2α3/β3参与的磷转运体胞内运输；并通过磷转运体基因启动子片段切割融合GUS报告基因转化水稻等方法探析SL直接调控磷转运体的作用机制，阐明水稻磷素高效利用与SL的关系，为培育磷素高效作物品种提供重要理论基础。

充分挖掘作物高效吸收利用磷的生物学潜力，对于养分资源高效利用具有重要意义。独脚金内酯(SL)作为新发现的植物激素，已经被证实在低磷条件下可通过调控根系生长等途径提高植物对磷的吸收利用。我们发现，低磷条件下SL直接促进了水稻对磷的吸收转运，但其中涉及的机制还不清楚。因此我们利用现有的磷调控网络背景结合相关磷转运体的转基因材料和SL合成及信号突变体材料，通过添加外源独脚金内酯rac-GR24以及32P同位素标记等方法证明独脚金内酯影响磷的转运而不是磷的吸收；利用qRT-PCR检测磷转运体RNA水平，发现独脚金内酯会诱导水稻磷转运基因表达上调，且主要通过调控转录因子OsPHR2；同时发现外源rac-GR24正调控水稻体内的OsPHR2蛋白水平，研究发现OsSPX4作为负调控因子与OsPHR2结合来调控OsPHR2进出细胞核从而调控下游基因的表达，而外源独脚金内酯rac-GR24处理后，随着rac-GR24供应时间的延长OsSPX4与OsPHR2的互作逐渐消失，OsPHR2的核质比升高, OsPHR2更多的向核转移进而调控下游基因。该项目充分阐明水稻磷素高效利用与独脚金内酯(SL)的关系，为培育磷素高效作物品种提供重要理论基础。