Proline helps plants deal with salt stress by protecting cells and regulating water balance. Chicory seedlings were exposed to different levels of salt to see how proline levels and enzyme activities changed. The enzyme δ-OAT increased, P5CS initially increased then decreased, and ProDH decreased with higher salt levels. Proline levels went up with more salt, but then decreased over time. The study found that different pathways are activated depending on the salt concentration, with the glutamate pathway being more important at low salt levels and the ornithine pathway taking over at high salt levels.