Identification of Lepidium draba Δ 1 -pyrroline-5-carboxylate Synthetase ( P5CS ) and Assessment of its Expression Under NaCl stress: P5CS Identification in L. draba plant

The aims of this study were identification of Δ1-pyrroline-5-carboxylate synthetase (P5CS) gene and effect of different concentrations of NaCl on P5CS gene expression level and some biochemical traits of L. draba seedlings. The 5-day-old L. draba seedlings were treated by different concentrations (0, 50, 100, 200 and 300 mM) of NaCl for 14 days. Identification of the P5CS gene was done by purification of total RNA, synthesis of cDNA library and amplification of the cDNA in the presence of specific primers followed by sequencing. The gene expression level of P5CS was done using real-time PCR method. Thereafter, the effect of salt stress was evaluated on peroxidase and catalase enzymes activities and carotenoids content, chlorophyll, total protein and proline contents. Identification and characterization of P5CS mRNA were performed and its sequence partially registered in gene bank. The data showed that P5CS gene expression level and the proline content increased with increasing concentrations of NaCl up to 300 mM. Peroxidase and catalase activities as well as the total protein content were enhanced by increasing the concentrations of NaCl in all samples. Chlorophyll and carotenoids contents were significantly decreased by salinity stress. According to the results, a direct relationship was found between proline content and P5CS gene expression level. Furthermore, these results also provide an insight into the response of this medicinal plant to salt stress.