Identification and characterization of drought stress protein on soybean (Glycine max L. Merr)

This research aims to identify the changing of protein of soybean (Glycine max L. Merr) in response to drought stress. Four tolerant varieties of soybean Tanggamus, Nanti, Seulawah, Tidar, two moderately tolerant varieties Wilis and Burangrang and one sensitive variety Detam-1 were subjected to drought stress using limitation of watering. Proteins were isolated from leaf using presipitation method with TCA, and then run on SDS-PAGE. The suspected protein then sequenced at Proteomics International, Western Australia and analyzed using MalditoffMass Spektrometer Proteomics Analyzer. Spectrum analysis based on hint peptide was identified using Mascot Sequence Matching Software and compare to the protein database and aligned using Clustal X software Bioedit and BLAST (Basic Local Alignment Search Tool) at NCBI. Two new protein band, 13 kDa and 52 kDa, identified in previous experiment were separated using 2D-PAGE. The result shows that the 13 kDa protein band in tolerant varieties were thicker when the plant subjected to drought stress than in normal condition. This protein show high (96%) homology to auxin binding protein and 88% homology to germin like protein, which has enzymatic activity as detoxification enzyme oxalate oxidase and superoxide dismutase which has a role in the drought tolerance mechanism.