PPT1在低磷诱导拟南芥根际酸化反应中的作用及分子机制研究

土壤中总磷含量并不很低，由于磷的低溶解和低移动特性，土壤有效磷含量常常不足，土壤缺磷已成为制约农业生产的一个重要因素。植物可通过形态结构和生理生化过程的变化，实现对磷的高效吸收和利用，以适应低磷环境。低磷胁迫诱导根际酸化，可增加土壤磷素的可溶性，提高土壤有效磷含量，但低磷诱导根际酸化反应的机制至今还不清楚。我们利用溴甲酚紫显色技术，建立了直观高效的根际酸化缺失拟南芥突变体的筛选方法，筛选得到一批低磷诱导根际酸化反应缺失突变体。 ppt1 是一个低磷诱导根际酸化缺失拟南芥突变体，PPT1蛋白同时具有钙调素结合结构和zip 转录因子的同源序列；生化和细胞学实验表明，PPT1 可与CAMx 和CAMy 在细胞核内发生互作。本项目将对ppt1 进行分子遗传学、细胞生理学、功能基因组学分析，揭示PPT1 调控低磷诱导根际酸化反应的分子机制，为培育土壤磷高效作物新品种奠定理论基础。

Phosphorus (P) is a essential elements ,which play an import role in the constitution of cellular components and in signal transduction processes.Plants acquire phosphorus in the form of phosphate (Pi), The concentration of which is often limited for plant uptake. Root-induced chemical and biological changes play a vital role in enhancing the bioavailability of soil P. We have developed a high-throughput screening system aimed at identifying components regulating low phosphate-induced rhizosphere acidification by visualization of rhizosphere pH with bromocresol purple as pH indicator. Dozens of the mutants were isolated from T-DNA insertion mutant library by this screening technology. ppt1 is one of the mutants we have isolated. ppt1 lost the function of low phosphate-induced rhizosphere acidification. PPT1-GFP was localized to the nucleus. PPT1 is predicted to encode a calmodulin-binding protein (CaMBP). We find that PPT1 can interact withCaMx and CaMy in the nucleus. We will identify the mechanism of PPT1 mediated low phosphate-induced rhizosphere acidification with molecular genetics and physiological technology. This result will benefit future crop breeding aimed at improving the ability of plants to acquire and utilize P.