Proteomic Analysis Of Alfalfa (Medicago Sativa L.) Root Proteins Under Salt Stress

The problem of salting and alkalinizing of fertile land, which decrease the produces of agricultureand influence environment, become more and more serious. The way, employing biotechnology toenhancing the ability of salt-alkaline tolerance of forage and culture plants, is effective to improve andutilize the salting and alkalining land resource. Cloning the related genes and studying the mechanism ofsalt-alkaline tolerance, are foundations of promoting the salt-alkaline tolerance of plants by transgenictechnology.The alfalfa 'zhong mu No.1' with high salt tolerance has been used as tested materials to study onthe discrepancy expression of alfalfa root proteom by the method of two-dimensional gel electrophoresis.Some important steps, such as sample preparation, isoelectric focusing, balancing and staining, werediscussed and improved. Comparing different methods of proteins extraction, we have concluded that themethod of phenol extraction methanol/ammonium acetate precipitation is suitable for the extraction ofalfalfa root proteins. And we also use a modified colloidal Coomassie Blue staining to obtain highsensitive and reproducible results. So we establish a technique method of 2-DE which is applied inalfalfa. Profiling the discrepancy expression of alfalfa root proteins under salt stress with the improvedmethod of two-dimensional gel electrophoresis, Out of more than 533 protein spots reproduciblydetected and analyzed, 59 spots showed significant changes under salt stress, 17 proteins wereup-regulated, 42 proteins down-regulated. These protein spots were analyzed by ImageMaster 2Dplatinum 5.0 software, leading to identification of molecular weights and pH values of these proteins.This study gives new insights into salt stress response in alfalfa roots and demonstrates the power of theproteomic approach in forage biology studies.