Spatial Divergence of PHR-PHT1 Modules Maintains Phosphorus Homeostasis in Soybean Nodules. Issue 1 (17th July 2020) - Lu, Mingyang
Abstract : Tissue-specific differentiation of phosphorus transporters coordinated with their regulators confers phosphorus homeostasis, regulating nodule development. Abstract : Maintaining phosphorus (Pi) homeostasis in nodules is the key to nodule development and nitrogen fixation, an important source of nitrogen for agriculture and ecosystems. PHOSPHATE-TRANSPORTER1 ( PHT1 ) and its regulator PHOSPHATE-STARVATION-RESPONSE1 ( PHR1 ), which constitute the PHR1-PHT1 module, play important roles in maintaining Pi homeostasis in different organs. However, the PHR1-PHT1 module and its functions in nodules remain unknown. We identified one PHT1 ( GmPHT1;11 ) and four PHR1 ( GmPHR1 ) homologs in soybean ( Glycine max ) plants, which displayed specific expression patterns in different tissues in nodules, similar to previously reported GmPHT1;1 and GmPHT1;4 . Through the integration of different approaches, GmPHR-GmPHT1 modules were confirmed. Combining our results and previous reports, we established multiple GmPHR-GmPHT1 modules acting in the infected or noninfected tissues in nodules. A single GmPHR had more than one GmPHT1 target, and vice versa. Therefore, overlapping and cross-talking modules monitored the wave of available Pi to maintain Pi homeostasis in nodules, which sequentially regulated nodule initiation and development. High levels of GmPHT1;11 enhanced Pi accumulation in nodules, increased nodule size, but decreased nodule number. Nitrogenase activity was also enhanced by GmPHT1;11 . Our findings uncover GmPHR-GmPHT1 modules in nodules, which expands our understanding of the mechanism of maintaining Pi homeostasis in soybean plants.