• Most land plants associate with arbuscular mycorrhizal fungi to secure mineral nutrient acquisition, especially that of phosphorus. A phosphate starvation response (PHR)-centered network regulates arbuscular mycorrhizal (AM) symbiosis. • Here, we identified 520 direct target genes for the rice transcription factor OsPHR1/2/3 during AM symbiosis using transcriptome deep sequencing and DNA affinity purification sequencing. These genes were involved in strigolactone biosynthesis, transcriptional reprogramming, and bi-directional nutrient exchange. • Moreover, we identified the receptor-like kinase, Arbuscule Development Kinase 1 (OsADK1) as a new target of OsPHR1/2/3. Electrophoretic mobility shift assays and transactivation assays showed that OsPHR2 can bind directly to the P1BS elements within the OsADK1 promoter to activate its transcription. OsADK1 appeared to be required for mycorrhizal colonization and arbuscule development. In addition, Hydroponic experiments suggested that OsADK1 may be involved in plant Pi starvation responses. • Our findings validated a role for OsPHR1/2/3 as master regulators of mycorrhizal-related genes involved in various stages of symbiosis and uncovered a new RLK involved in AM symbiosis and plant Pi starvation responses.