Plants use proline to protect themselves from harmful conditions like cadmium stress. When pea plants were exposed to cadmium, the youngest leaves had less proline at first, but then all leaves increased proline levels over time. Genes involved in proline production and breakdown were also affected by cadmium. Proline levels were not directly linked to abscisic acid, a plant hormone. Adding abscisic acid only increased proline in the youngest leaves. This shows that proline accumulation in pea plants under cadmium stress happens independently of abscisic acid signaling.