SlWRKY23 is a positive regulator of phosphate starvation response in tomato

Phosphate (Pi) starvation severely constrains plant growth, and elucidating its regulatory mechanisms is critical for enhancing phosphate use efficiency. Here, we identified SlWRKY23 as a key regulator of the phosphate starvation response (PSR) in tomato (Solanum lycopersicum). RNA-seq and qRT-PCR analyses showed that SlWRKY23 is strongly induced in root tips under Pi starvation, and its nuclear localization is consistent with its role as a transcription factor. SlWRKY23 is ubiquitously expressed, with the highest levels in roots. Functional analyses using slwrky23-cr mutants and SlWRKY23-overexpressing transgenic plants revealed that SlWRKY23 positively regulates PSR. Under Pi starvation, SlWRKY23 modulates root architecture by maintaining primary root elongation and lateral root density and length. SlWRKY23 also upregulates the expression of PSR genes, enhances the transcription and activity of acid phosphatase genes, and promotes organic acid secretion, thereby intensifying rhizosphere acidification to facilitate phosphorus acquisition. Together, SlWRKY23 positively regulates tomato PSR through root plasticity, induction of PSR genes, and enhanced phosphorus mobilization, providing insights into plant adaptation to Pi starvation.