Silencing of SlSPX1 and SlSPX2 promote growth and root mycorrhization in tomato (Solanum lycopersicum L.) seedlings.

Owing to the essential requirement of phosphorus (P) for growth and development, plants tightly control inorganic phosphate (Pi) homeostasis. SPX-PHR regulatory circuit not only control phosphate homeostasis responses but also root mycorrhization by arbuscular mycorrhiza (AM) fungi. Besides sensing Pi deficiency, SPX (SYG1/Pho81/XPR1) proteins also control the transcription of P starvation inducible (PSI) genes by blocking the activity of PHR1 (PHOSPHATE STARVATION RESPONSE1) homologs in plants under Pi-sufficient conditions.