Investigating the Expression of Induced Proteins in Leaves of Two Soybean Cultivars under Salt Stress by Two-Dimensional Electrophoresis Technique

Soybean plant has a lot of value in human nutrition, so the processed soy protein is a substitute for animal proteins, which is increasingly consumed. The main environmental stress in most regions of the world is salt stress, which has limited the growth and performance of crops. Therefore, the purpose of this research is to investigate the changes in the protein pattern of two soybean cultivars under salt stress using two-dimensional electrophoresis technique. An experiment was carried out in the crop year of 2018-2019 as a factorial based on a completely randomized design with three replications in University of Mohaghegh Ardabil. The test factors included the first factor of salinity stress (0, 3, 6 and 9 dS/m) and the second factor of soybean genotypes (DPX and Arian). To study and identify the proteins related to leaf development stages, total protein was extracted from soybean leaves based on TCA-acetone method and separated by two-dimensional electrophoresis method. In order to perform electrophoresis in the first dimension, an 18 cm strip gel with pH = 4-7 was used. The second dimension was put on 11 Percent acrylamide gel by SDS-PAGE method, and the electrophoresis device was first performed for 30 minutes with 50 V and then for 3 hours with 165 V. The findings showed that by performing two-dimensional electrophoresis, a number of reproducible protein spots were identified, of 14 protein spots related to DPX cultivar were significant at the five percent probability level, and 11 protein spots were in Arian cultivar. They showed significance in different levels of salinity stress. Also, 55 Percent of the detected proteins showed decreased expression and 19 Percent increased expression. 26 Percent of the identified proteins did not have regular and significant changes. The identified proteins are involved in various metabolic pathways such as energy metabolism, photosynthesis, respiration, antioxidant activities, message transmission, translation, transcription and cell wall. Most of the common proteins in DPX and Arian cultivars were chloroplastic enzymes and some of them were mitochondrial enzymes. The most changes were observed in the DPX variety (tolerant to salinity) and finally the least changes were observed in the sensitive Arian variety, which indicates the greater effort of the DPX variety to reduce the damage caused by salinity stress.