Overexpression of Δ1-pyrroline-5-carboxylate synthetase increases proline production and confers salt tolerance in transgenic potato plants

Proline (Pro) is known as compatible osmolyte accumulated by plant cells in response to salt and drought stresses. It is supposed to be an osmoprotectant involved in the protection of cellular structures under osmotic stress. Therefore, in an attempt to increase salt tolerance in potato, a pyrroline-5-carboxylate synthetase (P5CS) cDNA from Arabidopsis thaliana was transferred to potato plants via Agrobacterium-mediated transformation. This enzyme is responsible for conversion of glutamate to Δ1-pyrroline-5-carboxylate that is reduced to Pro. The resulting transgenic potato plants showed an important increase in Pro production levels compared to non-transgenics. This Pro accumulation was particularly enhanced in the presence of salt up to 100 mM NaCl. The transgenic potato plants also showed an improved tolerance to salinity through a much less altered tuber yield and weight compared to the non-transgenic ones.