Exogenous proline helps trifoliate orange plants cope with boron deficiency by reducing oxidative stress and promoting growth. The researchers found that adding proline increased proline levels in the leaves and roots, leading to less damage from boron deficiency. Proline also helped with the accumulation of boron in the roots and the formation of important cell wall components. Enzymes involved in proline metabolism played a role in this process, with ornithine pathway being crucial for proline production in the roots. Overall, exogenous proline triggers internal mechanisms that improve plant tolerance to boron deficiency and support root growth.