Gene Cloning and Expression of the Pyrroline-5-carboxylate Reductase Gene of Perennial Ryegrass (Lolium perenne)

Salt and drought limit the range of applications of perennial ryegrass (Lolium perenne L.), which is one of the important turf and forage grasses. Previous studies have suggested that pyrroline-5-carboxylate reductase (P5CR) might play a central role in proline accumulation in plants that are responsive to stresses. In the present study, the Lolium perenne L. pyrroline-5-carboxylate reductase (LpP5CR) gene was cloned from leaves of the cultivar ‘Derby’ using the RACE technique. The full-length LpP5CR gene was 1 047bp in length, which comprised an open reading frame (ORF) of 840bp in size. Sequence alignment revealed that the putative LpP5CR had a 94.3% similarity to TaP5CR. qRT-PCR displayed that the mRNA levels of the LpP5CR gene were almost the same as that in the roots, stems, and leaves of perennial ryegrass seedlings subjected to normal condition or NaCl treatment for 1h. Moreover, the transcription level of LpP5CR was up- or down-regulated with NaCl, polyethylene glycol (PEG), cold, or abscisic acid (ABA) treatment for 3 to 48h. In addition, confocal microscopy localized the GFP-LpP5CR fusion protein to the cytoplasm of onion epidermal cells. These findings suggest that LpP5CR encodes a cytoplasmic P5CR protein that plays an important role in the response of perennial ryegrass to various stresses.