L-Proline amino acid get incorporated in proteins which ultimately determines its diverse roles in plant stress tolerance majorly in osmotic adjustment. It also provides the stability to proteins under adverse environmental stresses.

But there is no naturally known mechanism to incorporate D-Proline into proteins in plants, hence L-Proline amino acid found to play crucial role in various stresses.

@Gopal Kalwan Thanks for the information. Could you please share some references from where I might get a deeper understanding on this topic.

Article L-Proline and D-Proline (Chiral Amino Acid Catalysts)