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

• Published in: Plant science (Limerick) 2023-08, Vol.333, p.111723-111723, Article 111723
• Main Authors: Singh, Naorem Ronald Reagan, Roychowdhury, Abhishek, Srivastava, Rajat, Akash, Gaganan, Gayathri Areekkare, Parida, Adwaita Prasad, Kumar, Rahul
• Format: Article
• Language: English
• Subjects: Arbuscular mycorrhiza fungi; Gene Expression Regulation, Plant; Mycorrhizae - physiology; Phosphates - metabolism; PHR; Pi homeostasis; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - genetics; Plant Roots - metabolism; Seedlings - genetics; Seedlings - metabolism; Solanum lycopersicum; Solanum lycopersicum - genetics; SPX; VIGS
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2023.111723

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. However, the roles of SPX members in Pi homeostasis and AM fungi colonization remain to be fully recognized in tomato. In this study, we identified 17 SPX-domain containing members in the tomato genome. Transcript profiling revealed the high Pi-specific nature of their activation. Four SlSPX members have also induced in AM colonized roots. Interestingly, we found that SlSPX1 and SlSPX2 are induced by P starvation and AM fungi colonization. Further, SlSPX1 and SlSPX2 exhibited varying degrees of interaction with the PHR homologs in this study. Virus-induced gene silencing-based (VIGS) transcript inhibition of these genes alone or together promoted the accumulation of higher total soluble Pi in tomato seedlings and improved their growth. It also enhanced AM fungi colonization in the roots of SlSPX1 and SlSPX2 silenced seedlings. Overall, the present study provides evidence in support of SlSPX members being good candidates for improving AM fungi colonization potential in tomato. •Solanum lycopersicum (tomato) genome encodes 17 SPX members.•Transient silencing of SlSPX1 and SlSPX2 activates phosphate transport genes and enhance Pi uptake.•Silencing of SlSPX1 and SlSPX2 enhanced mycorrhization in tomato roots.•SlSPXs silencing caused stronger induction of mycorrhizal responsive genes in tomato seedlings.