A novel role of the calcium sensor CBL1 in response to phosphate deficiency in Arabidopsis thaliana

Phosphorus acts as an essential macroelement in plant growth and development. A lack of phosphate (Pi) in arable soil and phosphate fertilizer resources is a vital limiting factor in crop yields. Calcineurin B-like proteins (CBLs) act as one of the most important calcium sensors in plants; however, whether CBLs are involved in Pi deficiency signaling pathway remains largely elusive. In this study, we utilized a reverse genetic strategy to screen Arabidopsis thaliana T-DNA insertion mutants belonging to the CBL family under Pi deficiency conditions. The cbl1 mutant exhibited a relatively tolerant phenotype, with longer roots, lower anthocyanin content, and elevated Pi content under Pi deficiency, and a more sensitive phenotype to arsenate treatment compared with wild-type plants. Moreover, CBL1 was upregulated, and the mutation of CBL1 caused phosphate starvation induced (PSIs) genes to be significantly induced under Pi deficiency. Histochemical staining demonstrated that the cbl1 mutant has decreased acid phosphatase activity and hydrogen peroxide concentrations under Pi deficiency. Collectively, our results have revealed a novel role of CBL1 in maintaining Pi homeostasis.