Selenomethionine and total methionine ratio is conserved in seed proteins of selenium-treated and nontreated soybean, flax, and potato
Fofana, B., Main, D., Ghose, K., Grimmett, M., Peters, R.D., Martin, R.A., Mester, Z., Yang, L., Locke, S., Sweeney, M. (2014). Selenomethionine and total methionine ratio is conserved in seed proteins of selenium-treated and nontreated soybean, flax, and potato, 54(5), 2251-2261. http://dx.doi.org/10.2135/cropsci2013.10.0711
Crop biofortification with Se is widely accepted. However, little is known about the efficiency of selenomethionine (Se-Met) incorporation into the seed and tuber protein fraction of crops. Here, we report on the efficiency of Se incorporation into the seed and tuber protein fraction of soybean, flax, and potato and the putative identity of some of the proteins that are likely targets for this random pretranslation modification. Soybean, flax, and potato plants received Se using different sodium selenate application methods and rates, and Se-Met was determined in seed, tuber, and their protein fractions. Selenium content in seed and tuber tissues and in protein fractions was increased by 2 to 86 times. The methionine (Met) pool was increased, as was the proportion of Se-Met in the Met pool, but the ratio of Se-Met:total Met was well conserved (1:1) between the treated and nontreated plants. After two-dimensional (2D) protein electrophoresis, five protein spots were identified as glycinin, trypsin inhibitor (soybean), patatin-3-Kuras-1, patain-B2, and phosphoenol carboxy kinase (potato), none of which showed S to Se substitution in their primary structure. Linking Se and three stress markers in fresh tuber extracts, glutathione (GSH) level, glutathione peroxidase (GPx), and glutathione reductase (GR) activities were increased by 20 to 35%. The data showed low protein modification in these non-Se-accumulator crops and indicated that rates of 5 to 10 g ha-1 Se, through foliar application, may ensure not only an adequate daily intake levels for humans but may also activate antioxidant enzyme systems within the tuber tissue. © Crop Science Society of America.
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