Proteomic responses in shoots of the facultative halophyte Aeluropus littoralis (Poaceae) under NaCl salt stress

Salinity is an environmental constraint that limits agricultural productivity worldwide. Studies on the halophytes provide valuable information to describe the physiological and molecular mechanisms of salinity tolerance. Therefore, because of genetic relationships of Aeluropus littoralis (Willd) Parl. with rice, wheat and barley, the present study was conducted to investigate changes in shoot proteome patterns in response to different salt treatments using proteomic methods. To examine the effect of salinity on A. littoralis proteome pattern, salt treatments (0, 200 and 400mM NaCl) were applied for 24h and 7 and 30 days. After 24h and 7 days exposure to salt treatments, seedlings were fresh and green, but after 30 days, severe chlorosis was established in old leaves of 400mM NaCl-salt treated plants. Comparative proteomic analysis of the leaves revealed that the relative abundance of 95 and 120 proteins was significantly altered in 200 and 400mM NaCl treated plants respectively. Mass spectrometry-based identification was successful for 66 out of 98 selected protein spots. These proteins were mainly involved in carbohydrate, energy, amino acids and protein metabolisms, photosynthesis, detoxification, oxidative stress, translation, transcription and signal transduction. These results suggest that the reduction of proteins related to photosynthesis and induction of proteins involved in glycolysis, tricarboxylic acid (TCA) cycle, and energy metabolism could be the main mechanisms for salt tolerance in A. littoralis. This study provides important information about salt tolerance, and a framework for further functional studies on the identified proteins in A. littoralis.