A Proteomic Approach To Analyze Soybean Seed Germination

A proteomic approach was used to analyze differential expression of proteins during soybean(Glycine max) N2899 seed germination at specific stages of 0h, 8h, 36h and 60h after imbibition. The results show that on the pH3-10 2-D gels stained by coomassie brilliant blue, PDQuest image software detected about 350 protein spots, of which 31 spots show more than 2.5-fold change in abundance, and most of soybean seed storage proteins weren't mobilized during seed germination. At the first stage of germination, 13 proteins' abundance changed. At the second stage, the quantities and categories of differential proteins increased and 21 proteins' abundance dynamically changed. During the protrusion of radicle, 17 proteins' abundance reached a peak. These suggested that the internal metabolisms of imbibition seeds become more active. These 31 proteins treated by tryptic in-gel digestion were characterized by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and peptide mass fingerprintings of all were obtained. Soybean UniGene database was used to identify these proteins. Only 7 proteins were identified. They were proglycinin A_1aB_1b, subunit, nucleoside diphosphate kinase, glyceraldehyde 3-phosphate dehydrogenase, Thioredoxin fold, 35 kDa seed maturation protein, heat shock protein and seed maturation protein PM36. The potential functions of these proteins during seed germination were discussed.Using the same methods, we analyzed proteins whose abundance changed in response to non-lental concentration of 100mM NaCl stress in seed germination of Lee68 and N2899 soybean cultivars. PDQuest image software detected about 350 protein spots on pH3-10 2-D gels. However, on pH4-7 2-D gels, it could be detected about 650 protein spots. Among these, 18 proteins show changes in abundance as a result of treatment of salt. After searching soybean UniGene database, 9 proteins were successfully identified, for example ferritin, 20S proteasome beta subunit, GST 9, GST 10, seed maturation protein PM36. The results indicate that these proteins may play an important role in defense mechanisms against salt stress. We also detected endogenous IAA, GA, ABA and iPAs. The content and change range of hormones except iPAs in Lee68 were higher than in N2899, and the change pattern of 14 proteins was different in two cultivars under salt stress. These might closely relate to the resistance of cultivars. The research will help us understand the molecular mechanisms of salt stress.We used PCR and SDS-PAGE methods to identify soybean transformed by gagal gene. The results showed that exogenous gagalgene affected T₅ soybean storage proteins and the components of storage proteins show polymorthism.