Brassinosteroids application induces phosphatidic acid production and modify antioxidant enzymes activity in tobacco in calcium-dependent manner.

Brassinosteroids (BRs) are steroid hormones regulating various aspects of plant metabolism, including growth, development and stress responses. However, little is known about the mechanism of their impact on antioxidant systems and phospholipid turnover. Using tobacco plants overexpressing H/Cavacuolar Arabidopsis antiporter CAX1, we showed the role of Ca ion balance in the reactive oxygen species production and rapid phosphatidic acid accumulation induced by exogenous BR. Combination of our experimental results with public transcriptomic and proteomic data revealed a particular role of Ca-dependent phospholipid metabolizing enzymes in BR signaling. Here we provide novel insights into the role of calcium balance and lipid-derived second messengers in plant responses to exogenous BRs and propose a complex model integrating BR-mediated metabolic changes with phospholipid turnover.